Libor Šmejkal

Last decade brought an invasion of relativity into condensed matter physics. Spin Hall effect, topological insulators, graphene, Weyl/Dirac semimetals are among the prominent examples relying on relativistic quantum mechanics which can be grouped under the field of spintronics and its spin-offs. In my actual research I focus on exploring and inventing new emergent phenomena and mechanism within the realm of spinorbitronics and topological semimetals. We are considering effects combining challenges of fundamental physics problems (simulation of quantum field theory in solid state systems) and potentially industrially relevant nanodevices (anisotropic magnetoresistance and spin-orbit torque reading and writing of magnetic information). In collaboration with Prague, Cambridge, Jülich and Nottingham we investigate the new field of antiferromagnetic spintronics where some useful non-relativistic effects known from ferromagnets are not efficient or abandoned and thus relativistic effects can be of vital importance.

 
Antiferromagnets with specific symmetries host massles and massive Dirac fermions (on the picture) around Fermi level as emergent phenomenon in their bandstructure.
Antiferromagnets with specific symmetries host massles and massive Dirac fermions (on the picture) around Fermi level as emergent phenomenon in their bandstructure.
We calculate anisotropic magnetoresistance and spin-orbit torques in Heusler alloys (NiMnSb in the figure) from first-principles.
We calculate anisotropic magnetoresistance and spin-orbit torques in Heusler alloys (NiMnSb in the figure) from first-principles.
We simulate galvanomagnetic effects in non-collinear antiferromagnets, IrMn3 in the picture beeing famous example.
We simulate galvanomagnetic effects in non-collinear antiferromagnets, IrMn3 in the picture beeing famous example.
 

Current projects and interests:

  • Relativistic fermions in antiferromagnets (AFM). Three-dimensional variants of graphene are prommising candidates for future low power consumption nanoelectronic devices.
  • Anisotropic magnetoresistance and spin-orbit torque (SOT) in Heusler alloys. SOT was demonstrated at room temperature in NiMnSb microbars: Press release .
  • Symmetries and galvanomagnetic effects in non-collinear AFM. Magnetic texture of noncollinear AFM support the existence of anomalous and topological Hall effect.

 

Keywords: relativistic quantum mechanics, ab initio transport theory, DFT calculations (FLAPW, TBLMTO + CPA), minimal models; anisotropic magnetoresistance, spin Hall effect, anomalous Hall effect, spin-orbit torque, Dirac and Weyl fermions, magnetization dynamics, spin waves; antiferromagnets, topological semimetals, half-metalic ferromagnets.

Recent Publications

      “Route towards Dirac and Weyl antiferromagnetic spintronics”. L. Šmejkal, T. Jungwirth, and J. Sinova

Physics Status Solidi: Rapid Research Letters, Special Issue: Focus on Antiferromagnetic Spintronics

      “Electric Control of Dirac Quasiparticles by Spin-Orbit Torque in an Antiferromagnet”. L. Šmejkal, J. Železný, J. Sinova, and T. Jungwirth

Physical Review Letters

      “Room-temperature spin-orbit torque in NiMnSb”. C. Ciccarelli, L. Anderson, A. J. Ferguson, C. Gould, J. Gayles, J. Železný, L. Šmejkal, Y. Zhe, J. Sinova, F. Freimuth, and T. Jungwirth

Nature physics

Recent and upcoming conferences