Influence of Thickness and Interface on the Low-Temperature Enhancement of the Spin Seebeck Effect in YIG Films
Influence of Thickness and Interface on the Low-Temperature Enhancement of the Spin Seebeck Effect in YIG Films
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DOI：
10.1103/physrevx.6.031012
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发表时间：
2016-07-27
影响因子：
12.5
通讯作者：
Klaeui, Mathias
中科院分区：
文献类型：
--
作者：
Guo, Er-Jia;Cramer, Joel;Klaeui, Mathias
研究了重金属 (HM)/Y3Fe5O12 (YIG) 混合结构中温度依赖性纵向自旋塞贝克效应 (LSSE) 作为 YIG 薄膜厚度、磁场强度和不同 HM 检测材料的函数。 LSSE 信号随着温度的降低而大幅增强，导致低温下出现明显的峰值。我们发现 LSSE 峰值温度很大程度上取决于薄膜厚度和磁场。通过考虑材料主体中热激发磁振子的温度相关有效传播长度，我们的结果可以在磁振子驱动的 LSSE 框架中得到很好的解释。我们进一步证明，通过改变与相邻检测层的界面耦合，LSSE 峰值显着移动，揭示了超出当前讨论的体效应的更复杂的行为。通过界面的直接显微成像，我们将观察到的温度依赖性与 YIG 和相邻金属层之间的界面结构相关联。我们的结果强调了界面效应对 HM/YIG 系统中温度依赖性 LSSE 的作用，表明温度依赖性自旋流透明度显着依赖于界面条件。
The temperature-dependent longitudinal spin Seebeck effect (LSSE) in heavy metal (HM)/Y3Fe5O12 (YIG) hybrid structures is investigated as a function of YIG film thickness, magnetic field strength, and different HM detection materials. The LSSE signal shows a large enhancement with reductions in temperature, leading to a pronounced peak at low temperatures. We find that the LSSE peak temperature strongly depends on the film thickness as well as on the magnetic field. Our result can be well explained in the framework of magnon-driven LSSE by taking into account the temperature-dependent effective propagation length of thermally excited magnons in the bulk of the material. We further demonstrate that the LSSE peak is significantly shifted by changing the interface coupling to an adjacent detection layer, revealing a more complex behavior beyond the currently discussed bulk effect. By direct microscopic imaging of the interface, we correlate the observed temperature dependence with the interface structure between the YIG and the adjacent metal layer. Our results highlight the role of interface effects on the temperature-dependent LSSE in HM/YIG system, suggesting that the temperature-dependent spin current transparency strikingly relies on the interface conditions.