Large anomalous Nernst effect in thin films of the Weyl semimetal Co2MnGa
Large anomalous Nernst effect in thin films of the Weyl semimetal Co2MnGa
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DOI：
10.1063/1.5048690
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发表时间：
2018-11-19
影响因子：
4
通讯作者：
Goennenwein, Sebastian T. B.
中科院分区：
文献类型：
--
作者：
Reichlova, Helena;Schlitz, Richard;Goennenwein, Sebastian T. B.
Heusler化合物薄膜的磁热电特性是非常不同的。在这里，我们讨论了Co2MnGa薄膜的反常能斯特响应。我们系统地研究了反常能斯特系数随温度的变化，结果表明，与反常霍尔效应不同，Co2MnGa中的反常能斯特效应强烈地随温度变化。我们利用芯片上的测温技术来量化温度梯度，这使得我们能够直接评估反常的能斯特系数。我们将这些结果与参考的CoFeB薄膜进行了比较。结果表明，50 nm厚的Co2MnGa薄膜在300K时表现出-2µV/K的反常能斯特效应，而10 nm厚的Co2MnGa薄膜在体积磁化强度相近的情况下表现出明显较小的反常能斯特系数。这些发现表明，Co2MnGa中反常能斯特效应的微观来源是复杂的，可能包含来自斜散射、侧跳或本征Berry相的贡献。无论如何，在300K下观察到的-2µV/K的反常能斯特系数比在其他薄膜中测得的值要大，这使得该材料系统成为非常有希望的高效自旋量热电子器件的候选者。由AIP出版公司出版。
The magneto-thermoelectric properties of Heusler compound thin films are very diverse. Here, we discuss the anomalous Nernst response of Co2MnGa thin films. We systematically study the anomalous Nernst coefficient as a function of temperature, and we show that unlike the anomalous Hall effect, the anomalous Nernst effect in Co2MnGa strongly varies with temperature. We exploit the on-chip thermometry technique to quantify the thermal gradient, which enables us to directly evaluate the anomalous Nernst coefficient. We compare these results to a reference CoFeB thin film. We show that the 50-nm-thick Co2MnGa films exhibit a large anomalous Nernst effect of -2 mu V/K at 300 K, whereas the 10-nm-thick Co2MnGa film exhibits a significantly smaller anomalous Nernst coefficient despite having similar volume magnetizations. These findings suggest that the microscopic origin of the anomalous Nernst effect in Co2MnGa is complex and may contain contributions from skew-scattering, side-jump, or intrinsic Berry phase. In any case, the observed anomalous Nernst coefficient of -2 mu V/K at 300 K is large compared to the values measured in other thin films and makes this material system a very promising candidate for efficient spin-caloritronic devices. Published by AIP Publishing.