Thermal Excitation Spin Current by Light
Yi-Jia Chen1*, Ssu-Yen Huang1
1Physics, National Taiwan University, Taipei, Taiwan
* Presenter:Yi-Jia Chen
The generation of spin polarized current by the anomalous Nernst effect (ANE) and that of spin-wave spin current by the spin Seebeck effect (SSE) are most fascinating phenomena in the field of spin caloritonics. There are several methods to generate the temperature gradient, including Peltier heating, external heater, microwave heating, and light heating. Among them, light energy is one of the richest thermal energy harvesting sources. In this work, we investigate the spin-wave spin current and spin polarized current thermally excited by light in the framework of the SSE and the ANE, respectively. Comparing with other methods, such as the external heater, there are several unique properties, including the sign of spin-dependent signal and the time response, by the means of the light excitation. These properties arise as a result of the nature of the light penetration depth. By using light to excite spin current, we are able to qualitatively separate the interface and bulk contributions to resolve the previous ambiguity in the SSE. Most importantly, we find that temporal evolution of spin-charge conversion thermally stimulated by light is significantly faster by up to three order magnitude than that by the Joule heating of an external heater.

Keywords: Spin Caloritronics, Spin Seebeck effect, Anomalous Nernst effect, Pure spin current , spin-polarized current