Thermal Spin Injection and Interface Insensitivity in Permalloy/Aluminum Metallic Nonlocal Spin Valves
College of Natual Science and Mathematics, Physics and Astronomy
We present measurements of thermal and electrical spin injection in nanoscale metallic nonlocal spin valve structures. Informed by measurements of the Seebeck coefficient and thermal conductivity of representative films made using a micromachined Si-N thermal isolation platform, we use simple analytical and finite-element thermal models to determine limits on the thermal gradient driving thermal spin injection and calculate the spin-dependent Seebeck coefficient to be −0.5μV/K>Ss>−1.6μV/K. This is comparable in terms of the fraction of the absolute Seebeck coefficient to previous results, despite dramatically smaller electrical spin injection signals. Since the small electrical spin signals are likely caused by interfacial effects, we conclude that thermal spin injection is less sensitive to the ferromagnetic/nonmagnetic interface, and possibly benefits from the presence of oxidized ferromagnets, which further stimulates interest in thermal spin injection for applications in sensors and pure spin current sources.
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Hojem, A, Wesenberg, D, and Zink, B. L. "Thermal Spin Injection and Interface Insensitivity in Permalloy/aluminum Metallic Nonlocal Spin Valves." Physical Review. B 94.2 (2016): Physical Review. B, 2016-07, Vol.94 (2). Web. doi: 10.1103/physrevb.94.024426.