Enhancement of spin-seebeck voltage by spin-Hall thermopile

Voltage signals induced by the spin-Seebeck effect (SSE) are shown to be enhanced by introducing a thermopile structure consisting of two different metals with positive and negative spin-Hall angles. In the "spin-Hall thermopile", the positive and negative SSE signals in the metals are added to the output voltage in series. Here, we demonstrate that a Pt/Nb thermopile on an Y3Fe5O12 (YIG) slab exhibits the SSE voltage one order of magnitude greater than that in a plain Pt/YIG system. Since the spin-Hall thermopile enables sensitive detection of a spin voltage in a versatile manner, it will be useful to construct spin and heat sensors. (author)