Thermally induced spin polarization

目前的“热诱导自旋极化”项目是在SpinCaT优先方案的第二阶段内提出的。它致力于利用铂中的逆自旋霍尔效应以外的其他检测技术来检测热致自旋电流和自旋极化，因为已经证明铂中的邻近效应可能会引起寄生效应。这影响了例如在金属的纵向自旋塞贝克效应(LSSE)测量中的自旋检测，其中也存在反常能斯特效应(ANE)。这些技术包括磁光克尔效应(MOKE)、X射线共振磁反射率(XRMR)、隧道磁阻(TMR)和自旋能斯特磁热电势(SMTP)，这些技术将通过自旋Seebeck(SSE)或自旋能斯特效应(SNE)产生的热致自旋电流进行测试。在12/2011年，申请人加入了比勒费尔德的Reiss教授的团队，并开始在SpinCaT项目中研究镍铁氧体(NFO)薄膜和坡莫合金薄膜中的SSE。他和他的同事一起研究了纵向和横向几何形状(TSSE)随温度变化的SSE测量的贡献。LSSE和ANE的分离，以及从消失的TSSE中分离出ANE和平面能斯特效应(PNE)，如几个出版物所发表的那样。为了测试铂/NFO双层膜的邻近效应，开始了更多的实验，如XRMR，并在过去的几个月中建立了基于MOKE的矢量磁测量装置。详细描述了MOKE如何在掺铋的NFO和CoFeTb/Cu/Fm三层膜(FM=YIG，NFO，磁铁矿)中探测SSE引起的自旋极化。SNE将使用MOKE、XRMR和TMR以铂膜形式放映。此外，还将研究热致自旋霍尔磁阻，更准确地说是自旋能斯特磁热电势。初步实验正在进行中，并有望取得非常有趣的结果。由于SpinCaT优先计划的第一个周期已经完成，这项工作将与来自Garching、Regensburg、Mainz、Kaiserslautern、Osnabrück和Giessen的合作伙伴小组密切合作完成。

The present project 'Thermally induced spin polarization' is proposed within the second period of the SpinCaT priority programme. It is dedicated to alternative detection techniques for thermally induced spin currents and spin polarizations beyond the use of the inverse spin Hall effect in Pt, since it has been shown that proximity effect in Pt may induce parasitic effects. This affects the spin detection for example in longitudinal spin Seebeck effect (LSSE) measurements in metals, where the anomalous Nernst effect (ANE) is also present. These techniques to use are magnetooptic Kerr effect (MOKE), x-ray resonant magnetic reflectivity(XRMR), tunnel magnetoresistance (TMR) and spin Nernst magnetothermopower (SMTP) which will be tested by thermally induced spin currents generated by either spin Seebeck (SSE) or spin Nernst effects (SNE).In 12/2011 the applicant joined the group of Prof. Reiss in Bielefeld and started to investigate the SSE in nickelferrite (NFO) thin films and in permalloy thin films within the SpinCaT project. Together with his coworkers he studied ANE contributions for temperature-dependent SSE measurements for the longitudinal as well as for the transverse geometry (TSSE). The separation for LSSE and ANE was demonstrated as well as the separation of ANE and planar Nernst effect (PNE) from a vanishing TSSE as published in several publications. Further experiments like XRMR were started in order to test the proximity effect of Pt/NFO bilayers and a MOKE based vectorial magnetometry setup was built up in the last months.The present proposal is the first-time proposal for the applicant. It describes in detail, how SSE induced spin polarization will be detected by MOKE in Bi doped NFO and in CoFeTb/Cu/FM trilayers (FM=YIG, NFO, magnetite). The SNE will be shown in platinum films using MOKE, XRMR and TMR. Additionally, the thermally induced spin Hall magnetoresistance which is more correctly the spin Nernst magnetothermopower will be investigated. First experiments are in progress and promise very interesting results.As already in the first periode of the SpinCaT priority programme, this work will be done in close collaboration with partner groups from Garching, Regensburg, Mainz, Kaiserslautern, Osnabrück and Giessen.