Thermally induced spin polarization

目前的项目“热诱导自旋极化”是在SpinCaT优先计划的第二阶段提出的。它致力于热诱导自旋电流和自旋极化的替代检测技术，而不是使用Pt中的逆自旋霍尔效应，因为已经证明Pt中的邻近效应可能诱导寄生效应。这影响了自旋检测，例如在金属的纵向自旋塞贝克效应（LSSE）测量中，反常能司特效应（ANE）也存在。这些技术是磁光克尔效应（MOKE）、x射线共振磁反射率（XRMR）、隧道磁电阻（TMR）和自旋能思特磁热电能（SMTP），它们将通过自旋塞贝克效应（SSE）或自旋能思特效应（SNE）产生的热诱导自旋电流进行测试。2011年12月，申请人加入了Bielefeld的Reiss教授的小组，并开始在SpinCaT项目中研究镍铁氧体（NFO）薄膜和permalalloy薄膜中的SSE。与他的同事一起，他研究了ANE对纵向和横向几何（TSSE）的温度依赖SSE测量的贡献。在一些出版物中，我们证明了LSSE和ANE的分离，以及ANE和平面能思特效应（PNE）从消失的TSSE中分离出来。为了测试Pt/NFO双层层的接近效应，开始了XRMR等进一步的实验，并在过去几个月建立了基于MOKE的矢量磁强计装置。目前的提案是申请人的第一次提案。详细描述了在Bi掺杂的NFO和CoFeTb/Cu/FM三层（FM=YIG， NFO，磁铁矿）中如何用MOKE检测SSE诱导的自旋极化。SNE将通过MOKE， XRMR和TMR在铂薄膜中显示。此外，还研究了热致自旋霍尔磁阻，即更准确的自旋能态磁热电能。第一批实验正在进行中，有望得到非常有趣的结果。与SpinCaT优先方案的第一阶段一样，这项工作将与来自加尔兴、雷根斯堡、美因茨、凯泽斯劳滕、奥斯纳布尔<e:1>克和吉森的伙伴小组密切合作。

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.