Seminarium Fizyki Materii Skondensowanej
2006/2007 | 2007/2008 | 2008/2009 | 2009/2010 | 2010/2011 | 2011/2012 | 2012/2013 | 2013/2014 | 2014/2015 | 2015/2016 | 2016/2017 | 2017/2018 | 2018/2019 | 2019/2020 | 2020/2021 | 2021/2022 | 2022/2023 | 2023/2024 | 2024/2025
2021-06-11 (Piątek)
Zapraszamy na spotkanie o godzinie 12:15 
Sebastian Kubis (Cracow University of Technology)Pasta Phases - stability and topology
Neutron star is the only place where nucleons are subjected to such unusualconditions that the initially spherical nuclei become extremely deformed. The competition between nuclear and electric forces leads to aformation of very elongated structures called pasta phases. Advanced numericalsimulations of last decade show formation of pastas with very richtopology. In this talk we present the stability analyses of the most simplestructures based on methods of differential geometry and also discuss thetopological characteristics of various shapes of pasta phases. Join Zoom Meetinghttps://us02web.zoom.us/j/83686899432?pwd=RXNtZkhtZFpLazVmMVRFY1BtVlI0Zz09Meeting ID: 836 8689 9432Passcode: cond-matt
2021-05-28 (Piątek)
Zapraszamy na spotkanie o godzinie 12:15
Paulo E. Faria Junior (Univ. of Regensburg)Excitonic signatures of spin-valley physics in transition metal dichalcogenides
Join Zoom Meeting https://us02web.zoom.us/j/83686899432? pwd=RXNtZkhtZFpLazVmMVRFY1BtVlI0Zz09 Meeting ID: 836 8689 9432 Passcode: cond-matt
2021-05-21 (Piątek)
Zapraszamy na spotkanie o godzinie 12:15
Paulo E. Faria Junior (Univ. of Regensburg)Excitonic signatures of spin-valley physics in transition metal dichalcogenides
Join Zoom Meetinghttps://us02web.zoom.us/j/83686899432?pwd=RXNtZkhtZFpLazVmMVRFY1BtVlI0Zz09Meeting ID: 836 8689 9432Passcode: cond-matt
2021-04-30 (Piątek)
Zapraszamy na spotkanie o godzinie 12:15
Roser Valenti (Goethe University, Frankfurt)Kitaev models and materials: where are we now?
In the search for novel materials' properties, the generation and manipulation of highly entangled quantum states is a grand challenge of solid state research. Amongst the most entangled proposed states are quantum spin liquids. In this context, the exactly solvable Kitaev Z2 spin-liquid model, for which finely tuned anisotropic interactions exactly fractionalize spins into fermionic Majorana spinons and gauge fluxes has activated an enormous amount of interest. Most specially since possible realizations may be achieved -as an example- in octahedral coordinated spin-orbit-coupled 4d5 and 5d5 insulators. However, the low symmetry environment of the known Kitaev materials also allows interactions beyond the Kitaev model that open possible new routes for further exotic excitations.In this talk I will present an overview on how the subtle interplay of spin, (multi-)orbital and lattice degrees of freedom conspire to produce such phases and will discuss materials realizations and our present understanding of such systems. Join Zoom Meetinghttps://us02web.zoom.us/j/83686899432?pwd=RXNtZkhtZFpLazVmMVRFY1BtVlI0Zz09Meeting ID: 836 8689 9432Passcode: cond-matt
2021-04-23 (Piątek)
Zapraszamy na spotkanie o godzinie 12:15
Magdalena Popielska [Birowska] (IFT UW)Electronic and optical properties of van der Waals layered magnets
Atomically thin, magnetic materials have recently gained a lot of attention in the field of two-dimensional (2D) materials. Single magnetic layers with critical temperature above room-temperature are extremely attractive for fundamental studies and could potentially be the basis for a new class of information storage. However, probing the magnetic order of the 2D systems by conventional magnetic experimental setups is very challenging. On the other hand, it is well known, that even in the single layer limit, semiconducting two-dimensional materials strongly absorb light. Therefore, optical spectroscopy is a good method for their characterization. In order to shed light on the intriguing phenomena of 2D magnetism, I will present theoretical investigations in the framework of the density functional theory (DFT) of the structural, electronic and optical properties of the layered materials from the large family of transition metal phosphorus trisulfides (MPS3). In particular, I will focus on excitonic properties of MnPS3 and I will compare the results for the bulk and monolayer system. The magnetic properties of alloy system Ni0.75Cr0.25PS3 and bilayer heterostructure NiPS3/FePS3 will be discussed. Finally, the impact of the intralayer and interlayer magnetism on the electronic structure for particular systems will be highlighted. Join Zoom Meetinghttps://us02web.zoom.us/j/83686899432?pwd=RXNtZkhtZFpLazVmMVRFY1BtVlI0Zz09Meeting ID: 836 8689 9432Passcode: cond-matt
2021-04-16 (Piątek)
Zapraszamy na spotkanie o godzinie 12:15
Piotr Wrzosek (IFT UW)Revisiting the problem of the single hole in an antiferromagnet
Propagation of the single hole introduced into the antiferromagneticground state is one of the most studied problems in "cuprate physics",for it can be solved in a relatively controlled manner. Recently arenewed interest into this topic has been triggered by the possibilityof simulating hole-doped antiferromagnets in the cold atom experiments.In this talk I would like to discuss some of our most recent studieson the propagation of the single hole in the antiferromagnet using themagnon language with a special attention paid to the interactionbetween the magnons. To this end, I will introduce an intuitivepicture which explains why the electron's spin and charge degrees offreedom can separate in a one-dimensional lattice, though a similarsituation cannot occur in two dimensions. Next, I will show thatthe string potential, which is believed to be felt by the hole movingin a two-dimensional Ising antiferromagnet, is significantly destroyedby the magnon-magnon interactions. Join Zoom Meetinghttps://us02web.zoom.us/j/83686899432?pwd=RXNtZkhtZFpLazVmMVRFY1BtVlI0Zz09Meeting ID: 836 8689 9432Passcode: cond-matt
2021-04-09 (Piątek)
Zapraszamy na spotkanie o godzinie 12:15
Annabelle Bohrdt [TU Munich, ITAMP and Havard] and Fabian Grusdt [LMU Munich]Parton dynamics and Regge trajectories of rotational meson states in strongly correlated quantum systems
Recent experimental advances, both in solids as well as quantum simulators, allow unprecedented microscopic studies of the structure of strongly correlated quantum matter. In the Fermi-Hubbard model, believed to underly high-Tc superconductivity, this allows to revisit a decades-old idea that strongly interacting electrons may fractionalize into partons — loosely speaking, the analogues of quarks in high-energy physics — called spinons and chargons. In this talk we will give an overview of recent theoretical and experimental results supporting this parton picture. We start by studying the dynamics of partons in one and two dimensions, with a particular focus on their detection in state-of-the-art quantum simulators. Then we propose a multi-photon extension of ARPES spectroscopy, applicable in solids or cold-atom platforms, and demonstrate how it allows to reveal hitherto unknown long-lived rotational meson states in the two-dimensional t-J model. Our finding is supported by state-of-the-art time-dependent DMRG simulations. Join Zoom Meetinghttps://us02web.zoom.us/j/83686899432?pwd=RXNtZkhtZFpLazVmMVRFY1BtVlI0Zz09Meeting ID: 836 8689 9432Passcode: cond-matt
2021-03-19 (Piątek)
Zapraszamy na spotkanie o godzinie 12:15
Maciej Maśka (Politechnika Wrocławska)Temperature-driven BCS-BEC crossover in a coupled boson-fermion system
Motivated by strongly correlated and frustrated systems, we propose an effective model that describes the dynamics of pairs of opposite spin fermions scattering from localized bosons. Integrating out one of the degrees, either the bosons or fermions, generates temperature-dependent long-range effective interactions between the entities that we investigate using Monte Carlo techniques. The behavior of bosons is dominated by vortex-antivortex unbinding, with effective interboson interactions beyond the nearest-neighbor Josephson coupling of phases. Remarkably, in the fermion sector we observe a temperature-driven phase transition from a SC phase with a BCS spectral function that shows a gap minimum on the underlying Fermi surface to a conducting phase of pairs but with a BEC spectral function with a gap minimum at k=0. Tunneling and angle-resolved photoemission spectroscopy on Bose-Fermi mixtures in cold atomic systems and superconducting islands on graphene are some of the promising experimental platforms to test our predictions. Join Zoom Meetinghttps://us02web.zoom.us/j/83686899432?pwd=RXNtZkhtZFpLazVmMVRFY1BtVlI0Zz09Meeting ID: 836 8689 9432Passcode: cond-matt
2021-03-12 (Piątek)
Zapraszamy na spotkanie o godzinie 12:15
Dieter Vollhardt (University of Augsburg)Superfluid helium-3: A test system for universal concepts in physics
Since their discovery in 1971 the superfluid phases of helium-3 have proved to be an ideal testing ground for many fundamental concepts of modern physics. Phenomena such as unconventional Cooper pairing, macroscopic quantum coherence, the spontaneous breaking of large symmetry groups, and the formation of exotic topological defects are not only important in condensed matter physics, but provide important links to particle physics and even the structure of the early universe. In my talk I will give a non-technical introduction into the microscopic and macroscopic physics of superfluid helium-3.Join Zoom Meetinghttps://us02web.zoom.us/j/83686899432?pwd=RXNtZkhtZFpLazVmMVRFY1BtVlI0Zz09 Meeting ID: 836 8689 9432 Passcode: cond-matt
2021-01-29 (Piątek)
Zapraszamy na spotkanie o godzinie 12:15
Dorota Gotfryd (UW and UJ)Low energy models of Mott insulators with a finite spin-orbit coupling
This seminar summarises the main results of my PhD thesis. To this end, I will present two classes of the low-energy models for Mott insulators with a finite spin-orbit coupling. The following two questions will be addressed: (1) Which ground state properties of the Kitaev-like models can be measured experimentally and whether they can help with localizing Na2IrO3 and RuCl3 in the parameter space of these models? (2) How finite spin-orbit coupling can induce entanglement between the spin and orbital degrees of freedom? Join Zoom Meetinghttps://us02web.zoom.us/j/83686899432?pwd=RXNtZkhtZFpLazVmMVRFY1BtVlI0Zz09Meeting ID: 836 8689 9432Passcode: cond-matt