Faculty of Physics University of Warsaw > Events > Seminars > Solid State Physics Seminar

Solid State Physics Seminar

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room 0.06, Pasteura 5 at 10:15

dr Kingshuk Bandopadhyay (Postdoc, Functional Materials Technology Group ENSEMBLE3 Centre of Excellence, Poland)

“Optoelectronic properties of eutectic-based functional heterostructures "

Hybrid multicomponent materials of various shapes, sizes, and compositions with exciting optoelectronic properties, have become of particular interest in functional materials research. One of the promising approaches for the fabrication of 3D composite micro/nanostructures is based on the directional solidification of eutectic composites, during which two or more phases grow cooperatively forming natural heterostructures. Here, we will demonstrate two distinct cases of 3D eutectic heterostructures. Begin with the topological insulator-based eutectic composite where the existence of the metallic surface states and the formation of the electrical junction have been confirmed, shows a strong polarized THz emission. Next is the anisotropic transport properties of eutectic NiTiO3–TiO2 composites and their H2-reduced Ni-TiOx counterpart, the underlying physical mechanisms that govern their performance and the potential for future innovations are thoroughly explored.

room 0.06, Pasteura 5 at 10:15

Prof. dr hab. Andrzej Wysmołek (Faculty of Physics, University of Warsaw)

"MOVPE growth and applications of layered boron nitride"

Hexagonal boron nitride (h-BN) attracted great interest due to its excellent chemical stability, thermal conductivity and vast potential applications in deep-UV optoelectronics or in van der Waals heterostructures. It is clear that the bottleneck for industrial applications of hBN and other 2D materials is the possibility to fabricate high-quality large-area layers.In the first part of my presentation I will address this issue and show results on the growth of epitaxial h-BN on sapphire by metalorganic vapour-phase epitaxy (MOVPE) [1-4], which is currently regarded as one of the most promising growth techniques. I will show that the growth of a 2D material on a conventional substrate at high temperatures followed by a cool down to room temperature will lead to wrinkle formation [1,5, 6], which can be used to assess the quality of the grown layer.In the second part, I will focus on the properties of h-BN in general and of our epitaxial BN in particular, with a detailed characterization and discussion of the properties.The last part will be dedicated to applications of our MOVPE-grown h-BN ranging from large-area growth of vdW heterostructures [7], defects and single photon emitters [3, 8, 9], photonic applications like the growth of Bragg mirrors [10] to hydrogen generation and storage applications [1]. [1] J. Binder et al. Nano Letters 23, 1267−1272 (2023)[2] M. Tokarczyk et. Al. 2D Materials 10, 025010 (2023)[3] K. P. Korona et al. Nanoscale 15, 9864 (2023)[4] A. K. Dabrowska et al. 2D Materials 8, 015017 (2021)[5] J. Iwanski et al. Nanotechnology 34, 015202 (2023)[6] P. Tatarczak et al. Nanotechnology 35 175703 (2024)[7] K. Ludwiczak et al. ACS Appl. Mater. Interfaces 13, 47904 (2021)[8] M. Koperski et al. Scientific Reports 11:15506 (2021) [9] A. Dabrowska et al. Journal of Luminescence 269, 120486 (2024)[10] A. Ciesielski et al. Nanotechnology 35, 055202 (2024)

room 0.06, Pasteura 5 at 10:15

prof. dr hab. Piotr Perlin (Institute of High Pressure Physics, “Unipress”, PAS, Warsaw, Poland)

“Nitride Semiconductors-Based Laser Diode: Can We Fully Domesticate Wide Bandgap Semiconductors?"

Wide bandgap semiconductors are essential for the fabrication of visible light emitters,including both Light Emitting Diodes (LEDs) and Laser Diodes (LDs). The familyof materials that have enabled visible semiconductor optoelectronics comprisescompounds based on three binary materials: AlN, GaN, and InN. Only 30 years ago, widebandgap materials were considered to belong to a specific grey zone between true semiconductors (such as GaAs and Si) and insulators like diamond or NaCl. This categorization was not without reason, as wide bandgap materials are challenging in terms of growth, doping, and surface properties, including the fabrication of metal contacts. Additionally, for AlInGaN semiconductors crystallizing in the wurtzite structure, there is the issue of large internal dielectric polarization. However, as we know, most of these problems have been resolved over the past two decades, enabling the formation of a vast visible and UV light optoelectronics industry. In this presentation, I would like to focus on the remaining challenges posed by nature and use the example of semiconductor laser diodes to illustrate this ongoing battle.

room 0.06, Pasteura 5 at 10:15

Agnieszka Siemion (Politechnika Warszawska Wydział Fizyki)

"THz optics – achievements, challenges, and prospects"

dr hab. inż. prof. ucz

This presentation explores the landscape of terahertz (THz) optics, focusing on its notable achievements, current challenges, and future prospects. THz radiation, characterized by wavelengths considerably larger than those of visible light, induces substantial diffraction effects, profoundly impacting its interaction with matter. Moreover, the high coherence exhibited by many THz sources facilitates precise wave manipulation. However, in many cases we are within the near-field diffraction zone which has its peculiarities.THz radiation holds considerable promise across diverse fields, including medicine, non-destructive testing, and telecommunications. In medicine, THz waves offer non-invasive imaging capabilities, enabling detailed examination of biological tissues. Additionally, THz technology finds application in non-destructive testing, facilitating the detection of structural anomalies in materials without causing damage. Importantly, in modern telecommunications, THz radiation emerges as a transformative tool, facilitating high-speed data transmission and bandwidth expansion.The advancement of THz optics is closely intertwined with the exploration of various materials and manufacturing techniques. Different materials, ranging from dielectrics to semiconductors, offer unique properties conducive to THz wave manipulation. Furthermore, innovative manufacturing methods such as lithography, additive manufacturing, and metamaterial engineering play crucial roles in the development of novel THz optical devices.In summary, this presentation sheds light on the different achievements, existing challenges, and promising avenues in the realm of terahertz optics. By emphasizing its versatile applications and the role of material science and manufacturing innovation, it underscores the transformative potential of THz technology in shaping future advancements.

room 0.06, Pasteura 5 at 10:15

prof. Lino da Costa Pereira (University of Leuven KU Leuven , Belgium)

"Solid State Physics at the ISOLDE facility at CERN"

The ISOLDE facility at CERN has been a hub for the development of radioactive-probe techniques and their application in solid state physics and related fields. In this talk, I will give an overview of the radioactive-probe techniques that are currently available at ISOLDE and review some of my own recent work using some of them, from long-standing activities on doping of semiconductors [1,2], to emerging topics such as color centers in diamond for quantum technologies [3] and more multidisciplinary topics at the border with Nuclear Physics [4] and Particle Physics.[1] "Lattice location of Mg in GaN: a fresh look at doping limitations". Physical Review Letters 118, 095501 (2017)[2] "Lattice Location Studies of the Amphoteric Nature of Implanted Mg in GaN". Advanced Electronic Materials 7, 2100345 (2021)[3] "Direct Structural Identification and Quantification of the Split-Vacancy Configuration for Implanted Sn in Diamond". Physical Review Letters 125, 045301 (2020)[4] "Observation of the radiative decay of the 229Th nuclear clock isomer". Nature 617, 706 (2023).

room 0.06, Pasteura 5 at 10:15

dr Aleksandra Łopion (IFD UW)

Optically Detected Magnetic Resonance in (Cd,Mn)Te Quantum Wells with carrier gas

The ODMR technique allows us to study the local properties of magnetic ions incorporated in well-defined positions of the nanostructure. The basic information extracted from the ODMR spectra is the energy level structure of the Mn$^{2+}$ ion, which depends, e.g., on the local strain. Although the ODMR technique in diluted magnetic semiconductors is sensitive selectively to the magnetic ions, the detailed analysis of the measured signal reveals interactions within the magnetic ion system or between ions and charge carriers and the temperatures of the subsystems.The nominally undoped (Cd,Mn)Te/(Cd,Mg)Te quantum wells are typically p-type. The hole gas originates from the background doping of the (Cd,Mg)Te barrier material or the surface states. Depending on the conditions, the ODMR signal is affected by the carriers present in the sample in two ways. The first effect is the shift between the ODMR signals obtained on neutral and charged exciton (Knight shift). The second one is a change in the spin-lattice relaxation (SLR) rate in the presence of the carriers. The shape of the ODMR signal keeps the information about the temperature of the magnetic ions involved in the absorption of the MW. Studying it in detail can provide even more information about interactions with charge carriers.

room 0.06, Pasteura 5 at 10:15

dr hab. Adam Wojciechowski (Zakład Fotoniki Instytutu Fizyki im. Mariana Smoluchowskiego Uniwersytet Jagielloński)

Nitrogen-vacancy color centers in diamond and their applications

Color centers are defects in the crystal structure that can have drastically different properties from their host material. In recent years, an increasing number of groups have been focusing on color centers in diamond. Among the several hundred cataloged ones, the nitrogen-vacancy (NV) type has gained particular popularity. Such centers can be regarded as "quasi-atoms" trapped in the perfectly transparent crystal lattice of diamond, allowing for their long-term observation and precise optical measurements. An important feature of NV centers, especially for quantum metrology, is their possession of a nonzero spin (S=1) in the ground state and the ability to control it through optical and microwave fields. The small size of these centers, on the order of ~0.15 nm, makes them ideal for micro- and nanoscale metrology needs. Consequently, NV centers are used as highly sensitive sensors for measuring magnetic and electric fields, as fluorescent markers in imaging biological materials, and as optically initialized and read-out qubits in quantum information processing.In my presentation, I will discuss the physics underlying NV centers and various possibilities for their sensing applications, with particular emphasis on optically detected magnetic resonance. I will then focus on applications of NV centers in magnetometry and the potential for imaging magnetic fields with high spatial resolution. Finally, I will discuss the results of our work on the development of hybrid sensors based on diamond and glasses, as well as biological studies using NV-rich nanodiamonds.

room 0.06, Pasteura 5 at 10:15

dr inż. Michał Gawełczyk (Wydział Podstawowych Problemów Techniki, Instytut Fizyki Teoretycznej, Politechnika Wrocławska)

"From electron hopping between dopants in silicon to transport through their arrays "

The recent development of precise phosphorus donor placement in silicon [1,2] has attracted attention to the chains and arrays of such sites. They have already proven to be well suited for quantum simulation of the Extended Hubbard [3] and SSH [4] models and are of major interest for future quantum-information devices.In the experiment, gated systems of a few sites are studied electrically by measuring the current while sweeping gate voltages. The theory aims to simulate such diagrams and provide a two-way correspondence between the system and the simulated model. Thus, the need for a non-equilibrium transport theory of dopant systems arises. As the precision of donor placement approaches the level of creating single-atom sites, calculations of hopping and interaction matrix elements between such sites are also needed.I will present our recent work on evaluating hopping integrals between such donors and simulating the transport properties of their arrays. I will describe the method based on Bardeen's tunneling theory, which enables us to calculate hopping between various orbitals based on their wave functions only [5]. Our approach to transport is based on combining exact diagonalization with non-equilibrium Green's functions and allows the calculation of currents and other observables in the arrays. We study some of these effects to better understand the transport investigations of experimentally realized 3×3 arrays [3]. Among other things, we predict that such systems should be surprisingly immune to site disorder.[1] M. Fuechsle et al., Nature Nanotech. 7, 242 (2012).[2] J. Wyrick et al., Adv. Funct. Mater. 29, 1903475 (2019).[3] X. Wang et al., Nature Commun. 13, 6824 (2022).[4] Y. Chung et al., Nature 606, 694 (2022).[5] M.G., M. Zieliński, Phys. Rev. B 106, 115426 (2022).

room B2.38, Pasteura 5 at 11:00

prof. Jesus Zuniga-Perez (Majulab, Singapore and CRHEA, Valbonne, France)

Quantum Technologies Based on Point Defects in Nitrides

Quantum technologies based on point defects in nitridesJ. Zuniga-PerezMajulab, IRL 3654, CNRS, NTU, UCA, SU, NUS, Singapore CRHEA, UCA, CNRS, Rue Bernard Gregory, 06560 Valbonne, France *E-mail: jesus.zuniga@ntu.edu.sgPoint defects is crystalline materials can behave as artificial atoms with optical and spin properties that enable their exploitation as quantum emitters and quantum sensors.In this talk we will address the use of point defects in GaN as single-photon emitters operating at room-temperature and emitting in the telecom wavelength range, as well as their integration into photonic structures in order to modify their emission properties [1]. In the second part, we will exploit negatively-charged boron vacancies in hBN to implement a quantum strain sensor capable of providing spatially-resolved strain maps with micrometre resolution that, when combined with microRaman measurements, can determine the three principal strain tensor components [2]. Finally, we will integrate this quantum sensor with a plasmonic metasurface in order to enhance the emission of the point defects and augment its extraction, resulting in faster sensors displaying a better signal-to-noise ratio [3].[1] M. Meunier et al., Nanophotonics 12 (2023) 1405 [2] X. Lyu et al., Nano Lett. 22 (2022) 6553 [3] H. Cai et al., Nano Lett. 23 (2023) 4991

room 0.06, Pasteura 5 at 10:15

dr Marcin Białek (Instytut Wysokich Ciśnień PAN)

"Strong coupling of antiferromagnetic magnons with terahertz cavity photons"

In the regime of strong light-matter coupling, polariton modes are formed that are hybrid light-matter excitations sharing properties of both, a cavity mode and a matter mode. In the recent decade, ferromagnetic spin waves (magnons) coupling to cavity photons was intensively researched in the microwave range (few to tens of GHz). These studies are motivated by applications for quantum devices, due to the hybrid nature of magnon-polaritons, and interesting physics, like the observation of the dissipative coupling. However, magnon-polaritons can also be observed at much higher frequencies using antiferromagnetic materials, which have magnons in the THz range. We report on the observation of magnon-polaritons at THz frequencies, and how we use light-matter coupling to achieve cavity-mediated coupling of magnons in distant crystals, and cavity-mediated magnon-phonon coupling.

room 0.06, Pasteura 5 at 10:15

prof. dr hab. J.M.Baranowski (Łukasiewicz Research Network-Institute of Microelectronics and Photonics)

"Role of BGaN Layers in Nitride Technology "

The growth modes of heteroepitaxial layers of nitrides such as Stranski-Krastonow (SK) and Volmer-Weber (VW) in relation with dislocation generation are discussed. The MOCVD growth of BGaN/GaN layers is described and X-Ray Diffraction (XRD), Secondary Ion Mass Spectrometry (SIMS) and Scanning Electron Microscopy (SEM) measurements are presented. The unexpected change of growth mode of BGaN/GaN from SK to VW one at high growth temperature is observed in SEM images. This change of growth mode is first connected with formation of micro-voids at the BGaN/GaN interface. It is shown that micro-voids are responsible for blocking threading dislocations within the overgrown BGaN layer. This leads to lateral growth of the BGaN layer along the a-direction and a drastic reduction in the defects concentration shown by High-Resolution Photoinduced Transient Spectroscopy (HRPITS) and optical measurements.In addition, a change in the growth mode from Stranski–Krastonow, characteristic for MOCVD grown GaN, to laterally grown BGaN in the Volmer-Weber growth mode is observed. The mechanism responsible for such a dramatic growth mode change appears to be related to defect reactions leading to the formation a BN atomic layer at the BGaN growth front.Finally, it is suggested that the main role of BGaN layers in nitride technology may be connected with efficient way of dislocations elimination from grown GaN.

room 0.06, Pasteura 5 at 10:15

prof. dr hab. Stanisław Krukowski (Institute of High Pressure Physics of the Polish Academy of Sciences Warszawa)

“Gallium nitride melting – experiment and theory"

A review of the investigations of the pressure – temperature phase diagram is given. The early investigation were limited to low temperatures and low pressures which provided only basic understanding of the problem. More recent investigation combined very high pressure experiments and also classical molecular dynamic simulation which provided new insight into the problem of decomposition and congruent melting of GaN. Later research included ab initio data on high pressure wurtzite – rocksalt phase transition. Recent ab initio molecular dynamic provide more deep insight into the problem by separation of the GaN decomposition into Ga(l)+ N_2 mixture and GaN melting into Ga(l)+N solution. The obtained simulation results are in good agreement with the available experimental data.

room 0.06, Pasteura 5 at 10:15

prof. dr hab. Tomasz Dietl (International Research Centre MagTop, Institute of Physics, Polish Academy of Sciences, Warszawa, Poland)

“Dilute magnetic semiconductors on the way to quantum ampere and quantum kilogram"

In the talk, I will underline the present role of high-precision metrology in our daily life as well as in the search for a new physics by desktop experiments rather than in costly high-energy colliders. I will then present recent progress in fabricating (i) current standards of quantum dots’ charge pumps and (ii) resistance standards, exploiting the quantum Hall effect and quantum anomalous Hall effect, working in magnetic fields low enough to allow for combining with superconducting Josephson junctions that constitute the voltage standard. Such an integrated device establishes the ampere standard and the kilogram standard via the Kibble balance. In the main body of the talk, I will discuss the physics behind a potential role of quantum wells of dilute magnetic semiconductors, such as (Hg,Mn)Te [1] and (Hg,Cr)Te [2], in a new generation of resistance standards.[1] T. Dietl, Phys. Rev. Lett. 130 (2023) 086202; Phys. Rev. B 107 (2023) 085421.[2] C. Śliwa, T. Dietl, arXiv:2310.19856 (2023); G. Cuono, C. Autieri, T. Dietl, arXiv:2312.16732 (2023).

room 0.06, Pasteura 5 at 10:15

dr Grzegorz Mazur (QuTech & Kavli Institute for Nanoscience, TU Delft, The Netherlands)

"Experimental realization of Cooper pair splitters and Kitaev chain through quantum dots coupled through superconductors."

A decade of experimental research on topological superconductivity insemiconducting nanowires coupled to superconductors didn't yieldconclusive evidence for their experimental realization.However recent advances in fabrication and understanding of thedevices led to two major advancements in the field. Thanks to couplingquantum dots through a hybrid semiconductor superconducting segment itwas possible achieve practical control over crossed Andreev reflection(CAR) and elastic co-tunneling (ECT) between two quantum dots. Duringthe seminar, I will discuss the observation of parallel spincomponents, depending on the interplay between the magnetic field andthe spin-orbit coupling in the nanowire device. I will also discusshow controlling CAR and ECT leads to a first realization of a minimalKitaev chain.Wang, G., Dvir, T., Mazur, G.P. et al. Singlet and triplet Cooper pairsplitting in hybrid superconducting nanowires. Nature 612, 448–453(2022).Dvir, T., Wang, G., van Loo, N. et al. Realization of a minimal Kitaevchain in coupled quantum dots. Nature 614, 445–450 (2023).UwagaSeminarium w trybie HybrydowymFaculty of Physics room 0.06link to remote mode:https://zoom.us/j/7218838148szczegóły patrz instrukcja :instrukcja: (pdf file)AttentionThe seminar in the Hybrid modeFaculty of Physics room 0.06for details see instruction :instruction: (pdf file)

room 0.06, Pasteura 5 at 10:15

Dr hab. Michał A. Borysiewicz (Sieć Badawcza Łukasiewicz - Instytut Mikroelektroniki i Fotoniki)

"ZnO:Al as a contact electrode for GaN-based laser diodes "

Although GaN-based light emitting devices have revolutionized everyday life in the last decades, the research on the topic is still intense.One particular area is in the processing and packaging of devices, where recently new developments in the field of ohmic contacts have been demonstrated.The standard Ti/Al/TiN/Au and Ni/Au alloyed ohmic contacts are well established for n-GaN and p-GaN respectively, but new ideas,such as transparent conducting oxide (TCO) - based solutions have been proposed with success in increasing device efficiency.This research is based on the most popular, but unsustainable TCO indium-tin oxide, ITO.This presentation will be focused on the applicability of another TCO based on earth-abundand materials,namely Al-doped zinc oxide (AZO) and its application in ohmic contacts to both n- and p-type GaN layers in laser diodes.By appropriate engineering of the deposition process room-deposited AZO was achieved with record low conductivity.This makes it compatible with lift-of photolithography. A series of interface engineering steps will be presented resulting in high quality ohmic contacts.Finally, laser diode performance measurements will be shown indicating that the new AZO-based contacts improve the efficiency of the devices when compared with traditional metallizations.This research was supported by the National Centre for Research and Development, Poland, project 'OxyGaN' M ERA.NET2/2019/6/2020UwagaSeminarium w trybie HybrydowymFaculty of Physics room 0.06link to remote mode:https://zoom.us/j/7218838148szczegóły patrz instrukcja :instrukcja: (pdf file)AttentionThe seminar in the Hybrid modeFaculty of Physics room 0.06for details see instruction :instruction: (pdf file)

room 0.06, Pasteura 5 at 10:15

dr hab. Maciej Zgirski (Institute of Physics, Polish Academy of Sciences, Warsaw)

"Quantum thermodynamics with a single superconducting vortex "

We introduce the Single Vortex Box (SVB) – a nanodevice that allows to treat a single superconducting vortex as a macroscopic, albeit quantized "particle", which can be created and annihilated with pulses of electrical current. Our pioneering demonstration is a pivotal step towards the development of the vortex electronics i.e. memory cells, superconducting diodes, and logical elements. Using the method of fast time-resolving switching thermometry [1], we measure the temperature rise and the subsequent thermal relaxation of the SVB resulting from the expulsion of just a single magnetic field vortex. Our experiment thus provides a calorimetric estimation of the dissipation in a superconductor due to a single moving vortex. This is a feat of the fundamental importance that has never been accomplished before, which belongs to the emerging field of the experimental quantum thermodynamics.1. M. Zgirski, M. Foltyn, A. Savin, A. Naumov, K. Norowski, Heat Hunting in a Freezer: DirectMeasurement of Quasiparticle Diffusion in Superconducting Nanowire, Phys. Rev. Applied14, 044024 (2020)UwagaSeminarium w trybie HybrydowymFaculty of Physics room 0.06link to remote mode:https://zoom.us/j/7218838148szczegóły patrz instrukcja :instrukcja: (pdf file)AttentionThe seminar in the Hybrid modeFaculty of Physics room 0.06for details see instruction :instruction: (pdf file)

room 0.06, Pasteura 5 at 10:15

dr Maciej Koperski (Institute for Functional Intelligent Materials , National Universtiy of Singapore)

Topological spin textures coupled to optical and electrical excitations in insulating van der Waals ferromagnets

Magnetization in insulating van der Waals systems may form distincttextures strongly dependent on the film thickness. These may be directlyvisualized via magnetic force microscopy and/or Lorentz transmissionelectron microscopy, leading to emergence of multiple magnetic states(stripe domains or topologically protected skyrmions) that can besystematized in form of T-B phase diagram. The micromagnetic simulationssupport the experimental observations, granting insight into theinterplay between spin-spin interactions (exchange coupling, dipolarand/or Dzyaloshinskii–Moriya interaction, etc.). It is tempting toexplore how optical excitations (excitons exhibiting mixed Frenkel andcharge-transfer characteristics) and electrically injected chargecarriers in vertical tunnelling junctions interact with magnetic order.Overall, a strongly correlated system arises exhibiting coupling betweencharge carriers and magnetization, consequently providing a variety ofcontrol knobs for its optoelectronic and magnetic properties.UwagaSeminarium w trybie HybrydowymFaculty of Physics room 0.06link to remote mode:https://zoom.us/j/7218838148szczegóły patrz instrukcja :instrukcja: (pdf file)AttentionThe seminar in the Hybrid modeFaculty of Physics room 0.06for details see instruction :instruction: (pdf file)

room 0.06, Pasteura 5 at 10:15

dr hab. inż. Wojciech Wróbel , prof. PW (Politechnika Warszawska Wydział Fizyki Zakład Joniki Ciała Stałego)

"Ionic conductors – on oxide ion transport in crystals"

Solid state materials with high ionic conductivity are widely studied as a critical components of various electrochemical devices. Ceramic oxide ion conductors are currently applied in SOFC fuel cells, gas sensors, electrolysers or oxygen pumps. The long-range transport of oxygen ions in the solid state depends predominantly on the oxide ion vacancy concentration, but also on the distribution of vacancies in the crystal structure including, their ordering and interaction with the cationic and anionic sublattice. In this presentation characteristic features of long range ionic transport will be discussed for some of bismuth oxide based materials. These compounds show both highest known oxide ion conductivity, but at the same time face undesirable phase transitions and instabilities. Wide range of advanced experimental methods and computer modeling were used to study both the long- and short-range ordering of the structure. Changes in the distribution of oxygen ions and the concentration of defects will be discussed and their influence on ionic transport as well as the mentioned instabilities and phase transitions.UwagaSeminarium w trybie HybrydowymFaculty of Physics room 0.06link to remote mode:https://zoom.us/j/7218838148szczegóły patrz instrukcja :instrukcja: (pdf file)AttentionThe seminar in the Hybrid modeFaculty of Physics room 0.06for details see instruction :instruction: (pdf file)

room 0.06, Pasteura 5 at 10:15

dr hab. Iwona Stachlewska, prof. UW (Institute of Geophysics, Faculty of Physics, University of Warsaw)

"Remote-Sensing Laboratory, a world-class research team in atmospheric physics."

Remote-Sensing Laboratory (RS-Lab) has been established and vividly developed within the last 10 years thanks to research and development projects that were widely supported by the international scientific community in atmospheric sciences and finding agencies. This have established RS-Lab as one of the core sub-units at the Institute of Geophysics, Faculty of Physics, University of Warsaw.Nowadays, RS-Lab team is providing fee-free data to the highly esteemed observational networks of NASA (AERONET, PGN). We deliver high-level data to the European Center for Medium-Range Weather Forecasts (ECMWF), as a long-term contractor for the Copernicus Atmosphere Monitoring Service (CAMS). RS-Lab is also one of the most active observational platforms within the pan-European Aerosol, Cloud and Trace-Gases Research Infrastructure (ACTRIS-ERIC). Our R&D work related to development of the lidars for the European Space Agency (mobile Mie-Raman/fluorescence lidar, airborne high spectral resolution lidar) puts RS-Lab team in the forefront of the science in atmospheric physics.The excellent equipment at RS-Lab allows for multifactorial applications and closure studies on aerosols and clouds. The research, supported with modelling and satellite data results is unique studies at an unheard of level in this part of Europe. Consequently, this is resulting with vast number of high-level research publications in recognized journals.During seminar, I shall introduce the most significant achievements and research results of the team and will give an outlook to the nearest and long-term future of RS-Lab.UwagaSeminarium w trybie HybrydowymFaculty of Physics room 0.06link to remote mode:https://zoom.us/j/7218838148szczegóły patrz instrukcja :instrukcja: (pdf file)AttentionThe seminar in the Hybrid modeFaculty of Physics room 0.06for details see instruction :instruction: (pdf file)

room 0.06, Pasteura 5 at 10:15

prof. dr hab. Jerzy Wróbel (Institute of Physics, Polish Academy of Sciences Institute of Applied Physics, Military University of Technology)

"Classical and Quantum transport in SnTe micro- and nanostructures."

SnTe is a semiconductor compound belonging to a new group of topological matter called Topological Crystalline Insulators (TCI).In my talk, I will present the results of magnetotransport measurements on macroscopic samples and nano-structures made of SnTe/PbTe heterojunctions and CdTe/SnTe/CdTe quantum wells.The classical conductivity of macroscopic samples is described using the Mobility Spectrum Analysis (MSA), which shows that the electron-like and hole-like maxima observed in the mobility spectra are associated with single-carrier transport in a topological band and originate from the concave and convex parts of the constant energy surface on the (001) crystallographic plane.Then, I will describe the low-temperature electrical properties of 6- and 8-probe nano-structures significantly different from macroscopic samples.In particular, large conductance fluctuations and the quenching of the Hall effect are observed.These unusual results are interpreted as related to the transport of topological carriers, whose energy spectrum was quantized due to dimensionality reduction.Finally, I will provide evidence of the hydrodynamic flow of a viscous fermionic liquid in narrow SnTe channels, possibly related to forming a flat 1D energy band.Presented results are partially published in D. Śnieżek et al., Phys. Rev. B 107, 045103 (2023).UwagaSeminarium w trybie HybrydowymFaculty of Physics room 0.06link to remote mode:https://zoom.us/j/7218838148szczegóły patrz instrukcja :instrukcja: (pdf file)AttentionThe seminar in the Hybrid modeFaculty of Physics room 0.06for details see instruction :instruction: (pdf file)

room 0.06, Pasteura 5 at 10:15

dr Magdalena Birowska (Instytut Fizyki Teoretycznej Wydział Fizyki UW)

"Optical properties of Van der Waals Layered antiferromagnets

Atomically thin, magnetic materials have recently gained a lot ofattention in the field of two-dimensional (2D) materials [1]. Singlemagnetic layers with critical temperature above room-temperature areextremely attractive for fundamental studies and promising candidatesfor future spintronic applications. However, probing the magnetic orderof the 2D systems by conventional magnetic experimental setups is verychallenging. On the other hand, it is well known that even in the singlelayer limit, semiconducting two-dimensional materials strongly absorblight. Therefore, optical spectroscopy is a good method for theircharacterization. In order to shed light on the intriguing phenomena of2D antiferromagnets (AFM), I will present our recent theoreticalinvestigations [2-7] in the framework of the density functional theory(DFT) considering optical properties of the layered materials. Inparticular, I will focus on the representative AFM family, transitionmetal phosphorus trisulfides (MPX3), in respect to other 2D materials. Iwill cover currently puzzling research issues in respect to opticalproperties of layered materials.Refs:[1] M. Gibertini, et.al [2] Nat. Nanotech. 14, 408 (2019).[2] M. Birowska, et. al. Phys. Rev. B 103, L121108 (2021).[3] C. Autieri, M. Birowska, et. al. J. Phys. Chem. C 126, 6791 (2022).[4] R. Basnet, M. Birowska, et. al. Phys. Rev. Research 4, 023256(2022).[5] E. Geraffy, M. Birowska, et. al. arxiv.org/pdf/2208.10890 [3](2022).[6] M. Rybak, M. Birowska, et. al. arXiv:2308.13109v1 (2023).[7] J. Strasdas, M.Birowska, et. al. arxiv:2211.05501, accepted in NanoLetters.UwagaSeminarium w trybie HybrydowymFaculty of Physics room 0.06link to remote mode:https://zoom.us/j/7218838148szczegóły patrz instrukcja :instrukcja: (pdf file)AttentionThe seminar in the Hybrid modeFaculty of Physics room 0.06for details see instruction :instruction: (pdf file)

room 0.06, Pasteura 5 at 10:15

dr hab. Tomasz Antosiewicz, prof. UW (Instytut Geofizyki, Zakład Optyki Informacyjnej, Wydział Fizyki UW)

"Nanoparticle resonators - insights into fundamental properties and applications"

A nanoparticle antenna localizes the electromagnetic field in its vicinity, amplifying its intensity and proportionally increasing the efficiency of physical processes which depend of light. These properties stem from the shape, size, material, and environment and can be rationally tuned to investigate both fundmental properties of materials, as well as utilize nanoantennas in novel devices. My aim will be to introduce the role nanostructured optical antennas play in biosensing, light harvesting, material studies and strong light-matter interactions.UwagaSeminarium w trybie HybrydowymFaculty of Physics room 0.06link to remote mode:https://zoom.us/j/7218838148szczegóły patrz instrukcja :instrukcja: (pdf file)AttentionThe seminar in the Hybrid modeFaculty of Physics room 0.06for details see instruction :instruction: (pdf file)

room 0.06, Pasteura 5 at 10:15

(IFD UW)

Seminar is cancelled

room 0.06, Pasteura 5 at 10:15

prof. dr hab. Marek Potemski (LNCMI_CNRS, Grenoble IHPP_PAS, Warsaw FP_UW, Warsaw)

Electronic properties of “emerging” materials studied with optical magneto-spectroscopy

Optical magneto-spectroscopy will be demonstrated to be a relevant tool in solid-state physics,that is used to determine the electronic properties of different materials,and in particular of the 2D materials (graphene, semiconductors, antiferromagnets) as well as 3D “Dirac-like” compounds.The characteristic band structure and effects of interactions (electron-electron, electron-phonon, magnon-phonon) revealed with our studies in these materials will be discussed.UwagaSeminarium w trybie HybrydowymFaculty of Physics room 0.06link to remote mode:https://zoom.us/j/7218838148szczegóły patrz instrukcja :instrukcja: (pdf file)AttentionThe seminar in the Hybrid modeFaculty of Physics room 0.06for details see instruction :instruction: (pdf file)

room 0.06, Pasteura 5 at 10:15

dr hab. Włodzimierz Strupiński (VIGO Photonics S.A., 05-850 Ożarów Mazowiecki)

“Advanced MOCVD epitaxial technologies for emerging photonic applications"

VIGO Photonics is a global manufacturer of semiconductor materials and devices for the photonics and microelectronics industry. The Company’s product line includes advanced III-V epi-wafers, infrared detectors, and infrared detection modules. VIGO delivers off-the-shelf, OEM, and non-standard solutions, allowing its customers to develop products dedicated to their novel applications. The epitaxy division focuses on GaAs- and InP-based compounds for applications in EEL, VCSEL, QCL lasers, CPV, TPV, photodetectors, and RF devices.Review of challenges and achievements in MOCVD epitaxial growth of various epi-structures for photonic applications will be presented.UwagaSeminarium w trybie HybrydowymFaculty of Physics room 0.06link to remote mode:https://zoom.us/j/7218838148szczegóły patrz instrukcja :instrukcja: (pdf file)AttentionThe seminar in the Hybrid modeFaculty of Physics room 0.06for details see instruction :instruction: (pdf file)