Seminarium Fizyki Ciała Stałego

The spectacular achievement of the modern first-principles band theory is the prediction of topologically protected states of matter that host massless quasiparticles. Whereas an emergence of Dirac fermions in a topological insulator is solely expected on the surface, Weyl fermions are allowed to propagate through the bulk of a topological semimetal. However, in the known Weyl semimetals, conventional charge carriers exist in addition to the exotic quasiparticles, and thus a disclosure of their conduction properties remains challenging. Here, we address the mechanism giving rise to a marked deviation from the semiclassical B 2 behavior of an unsaturated extreme magnetoresistance (XMR) and commonly credited to the presence of topologically protected electronic states. For the topologically trivial semimetal LuAs, we observe a non-saturating XMR with an anomalous magnetic-field dependence B1.65 gained over more than two decades in magnetic fields up to nearly 60 T. Remarkably, the longitudinal and transverse magnetostrictions measured up to 16 T and down to 50 mK provide evidence for field-induced changes in the charge-carrier densities due to inter-band electron-transfer processes. Since these processes imply a shift of the Fermi level, one can suppose that field-induced strain-dependence of conventional charge carriers would result in even more interesting observations in topological semimetals.

In collaboration with J. Juraszek, Ł. Bochenek, A. Rudenko, M. M. Hosen, M. Daszkiewicz, Z. Wang, J. Wosnitza, Z. Henkie, M. Samsel-Czekała, and M. Neupane (Phys. Rev. Research – accepted). This work was supported by the Polish National Science Centre (Project No. 2016/21/B/ST3/02361).