Prof. Yoshinori Onose (Univ. of Tokyo)
"Topological transport phenomena of electrons and magnons"
Topological electronic properties in solids such as topological insulator and quantum Hall effect have been attracting great attention. In this talk, we present our recent two studies on novel transport properties relevant to topology. The first topic is topological Hall effect in Skyrmion crystal phase. Quite recently, the crystallization of Skyrmion spin texture was found in B20 transition metal compounds. In this talk, we present the real space image of the Skyrmion crystal obtained by the Lorentz TEM and discuss the Hall effect caused by the Berry phase originating from the topological spin arrangement of Skyrmion, which is termed topological Hall effect. The second topic in this talk is our recent finding of the Hall effect of magnons. While ordinary Hall effect is caused by the Lorentz force proportional to electronic charge, the Berry phase induced Hall effect is also expected for charge neutral particles. In fact, the Hall effects of photon and phonon were reported previously. Recently, we have succeeded in observing the magnon Hall effect in terms of thermal transport. These works were done in collaboration with X. Z. Yu, N. Kanazawa, T. Ideue, H. Katsura, Y. Shiomi, S. Ishiwata, D. Okuyama, S. Wakimoto, T. Arima, J. H. Han, K. Kakurai, N. Nagaosa, and Y. Tokura.