Abstrakt semináře je pouze v anglickém jazyce.
The physics of spin-orbit coupling (SOC), which is at the root of various noble physical phenomena such as exchange interactions, magnetoelectric and spin Hall effects, Fermi surface topology, has been adopted to explain electrical and magnetic properties of various materials. There has been a revival of interest in canting of spin magnetic moments for the late transition metal ions since the SOC plays an important role in such a system: It couples not only the spin and the orbital momentum of the 5d electrons, but also the spin and the lattice degree of freedoms. Sr2IrO4 is one of the famous examples of weak ferromagnetism in antiferromagnetic insulator. Their canted AFM order is explained by the lattice distortion, showing the canting angle which is nearly identical to that in the Ir-O-Ir bond.
In this presentation, SrRuO3 will be proposed as an opposite counterpart so-called weak antiferromagnetism in ferromagnetic metal. The spin canting in this system can be explained by Dzyaloshinskii-Moriya interaction (DMI), which is the first order perturbation term of the SOC on the S basis states since the strength of SOC in 4d shell is weaker than 5d. Our results using the noncollinear density-functional theory (DFT) plus on-site Coulomb repulsion U demonstrate that the spin canting is favoured with 0.6 meV/f.u. than the parallel one, in an appropriate range of U. The calculated exchange parameters reproduce well the reported data of the magnetic transition temperature and the magnon dispersion. The method to observe the magnon gap at low energy through the specific heat measurements will be discussed.
This event is supported by ESIF and MEYS (Project FZU researchers, technical and administrative staff mobility – CZ.02.2.69/0.0/0.0/18_053/0016627)