Interaction of subthermal magnons and phonons and their role for the transverse Seebeck effect

我们计划通过施加磁振子或声子温度梯度来研究亚热磁振子和声子在千兆赫频率区间内的相互作用，目的是了解它们在横向自旋塞贝克效应（TSSE）中的作用。我们将特别关注YIG薄膜中能量接近其光谱最小值的磁振子，而非相干磁振子和玻色-爱因斯坦凝聚体（BEC）将被讨论。研究了这些磁振子在热梯度下以及在千兆赫频率下的声学自旋泵浦的性质。TSSE的时间分辨研究将在YIG/Pt和NiFe/Pt两种模型系统中进行，而磁振子温度的梯度将相应地使用微波泵浦或自旋电流注入来产生。利用磁振子-磁振子和磁振子-声子时间之间的差异，时间分辨测量将澄清亚热磁振子在效应中的作用。

We plan to investigate interaction between subthermal magnons and phonons in the gigahertz frequency interval by applying a gradient of either magnon or phonon temperatures with targeting the understanding of their role in the transverse spin Seebeck effect (TSSE). Particular attention will be paid to magnons in YIG films with energies close to the minimum of their spectrum, whereas both incoherent magnons and Bose-Einstein condensates (BEC) will be addressed. Properties of these magnons in thermal gradient as well as under influence of acoustic spin pumping at gigahertz frequencies will be studied. Time-resolved studies of TSSE will be performed in two model systems: YIG/Pt and NiFe/Pt, whereas gradients of magnon temperature will be created using microwave pumping or spin-current injections, correspondingly. Taking advantage of a difference between magnon-magnon and magnon-phonon times, time-resolved measurements will clarify the role of subthermal magnons in the effect.