报告题目：Computational spin caloritronics

报 告 人：Ke Xia (Department of Physics, BUN)

报告时间：2016年3月3日下午4：00

报告地点：理学院郑裕彤大讲堂

报告摘要：Magnetization dynamics can be excited and detected electrically and thermally by metal contacts, which makes it a wonderful spin energy material. The crucial parameter for ferromagnet(F)|normal metal(N) interfaces is the spin mixing conductance that governs the absorption of a transverse spin current and the spin transfer torque. However, the spin-mixing conductance is a purely nonrelativistic concept, while there is mounting evidence that spin-orbit interactions at interfaces generate additional spin-flips and spin-orbit torques. We have solved this issue by introducing an “effective” spin mixing conductance for weakly relativistic materials. First ab initio results on ferrite|metal interface indeed indicate an enhancement that can be very significant for selected crystal orientations.

Massive particles, i.e. the electrons, as well as quasi particles, i.e. magnons, can carry a thermal spin current that generates torques at the interfaces. Based on the same theoretical frame as effective mixing conductance, we compute both kind of torques for magnetic tunnel junctions from first principles in order to validate their spin transfer power efficiency, switching speed, etc.