Nonlinear response in strongly correlated systems
 Date
 October 20 (Wed) at 17:00  18:15, 2021 (JST)
 Speaker

 Robert Peters (Lecturer, Department of Physics, Graduate School of Science, Kyoto University)
 Venue
 via Zoom
 Language
 English
Nonlinear responses in condensed matter are intensively studied because they provide rich information about materials and hold the possibility of being applied in diodes or highfrequency optical devices [14]. While nonlinear responses in noninteracting models have been explored widely, the effect of strong correlations on the nonlinear response is still poorly understood.
This talk will introduce a Green's function method to calculate nonlinear conductivities in strongly correlated materials [56]. Correlation effects are thereby included by the selfenergy of the material. I will then use this method to study the nonlinear conductivities in noncentrosymmetric felectron systems. The first system is a heavy Fermion system, where a nonreciprocal conductivity appears in the ferromagnetic phase. The nonreciprocal conductivity thereby always occurs perpendicular to the magnetization of the system and has a strong spin dependence, which might be advantageous for spintronic applications. The second system is a model corresponding to the WeylKondo semimetal Ce3Bi4Pd3, in which a giant spontaneous Hall effect without timereversal symmetry breaking has been observed [7]. This Hall effect can be explained as a nonlinear Hall effect in an inversionsymmetry broken Weylsemimetal. It has been shown that the nonlinear Hall effect is related to the Berry curvature dipole [4]. Our study shows that the magnitude of the experimentally observed nonlinear Hall effect can be explained by the strong correlations inherent in this felectron material [8].
*Detailed information about the seminar refer to the email.
References
 Y Tokura and N Nagaosa, Nature Comm. 9, 3740
 T Morimoto and N Nagaosa, Science Advances 2, DOI: 10.1126/sciadv.1501524
 Q. Ma et al., Nature 565, 337–342
 I Sodemann and L Fu, Rev. Lett. 115, 216806
 Daniel E. Parker, Rev. B 99, 045121
 Y Michishita and R Peters, Rev. B 103, 195133
 S Dzsaber et al., PNAS 118 e2013386118
 A Kofuji, Y Michishita, and R. Peters, Rev. B 104, 085151
 K Shinada and R Peters, in preparation