In this project, we investigate the coupling of the spin degree of freedom with electronic degrees of freedom across interfaces in ferromagnetic multilayers on the ultrafast time scale. For this purpose, we consider the excitation of the ferromagnetic material by a femtosecond laser pulse. The so created spin-polarized electrons with large energies respond to the applied field which is reflected in the longitudinal and transverse transport coefficients. We consider mainly the energy-dependent transversal transport properties, that are related to the anomalous and the spin Hall effect. In particular, we are interested in the time and spatial dependence of the charge- and spin-current distribution with respect to the interface. On the other hand, we investigate timedependent spin currents that are produced by the spin Hall effect if a THz electric field is applied to the nonmagnetic metal layer. Propagation of this spin current into the ferromagnetic layer causes a spin-transfer torque on the magnetization. Based on an ab initio description in combination with a semi-classical Boltzmann theory we aim at understanding the charge and spin current distributions on nanometer length scales and ultrafast time scales.

Publications

• Local spin Hall conductivity 
  T. Rauch, F. Töpler, and I. Mertig 
  Phys. Rev. B 101, 264206 (2020)  - DOI: 10.1103/PhysRevB.101.064206

• Elliptical Bloch skyrmion chiral twins in an antiskyrmion system 
  J. Jena, B. Göbel, T. Ma, V. Kumar, R. Saha, I. Mertig, C. Felser, and S. S. P. Parkins 
  Nat. Commun. 11: 1115 (2020)  - DOI: 10.1038/s41467-020-14925-6

• Ab initio design of quaternary Heusler compounds for reconfigurable magnetic tunnel diodes and transistors
  T. Aull, E. Şaşıoğlu, I. V. Maznichenko, S. Ostanin, A. Ernst, I. Mertig, and I. Galanakis 
  Phys. Rev. Mater. 3, 124415 (2019)  - DOI: 10.1103/PhysRevMaterials.3.124415

• Spin Seebeck and spin Nernst effects of magnons in noncollinear antiferromagnetic insulators 
  A. Mook, R. R. Neumann, J. Henk, and I. Mertig
  Phys. Rev. B 100, 100401(R) (2019)  - DOI: 10.1103/PhysRevB.100.100401

• Electrical writing, deleting, reading, and moving of magnetic skyrmioniums in a racetrack device
  B. Göbel, A. F. Schäffer, J. Berakdar, I. Mertig, and S. S. P. Parkin
  Sci. Rep. 9, 12119 (2019)  - DOI: 10.1038/s41598-019-48617-z

• Spin and charge currents induced by the spin Hall and anomalous Hall effects upon crossing ferromagnetic/nonmagnetic interfaces
  A. Hönemann, C. Herschbach, D. V. Fedorov, M. Gradhand, and I. Mertig
  Phys. Rev. B 99, 024420 (2019)  - DOI: 10.1103/PhysRevB.99.024420