Enhancement of Thermal Spin Injection Effects in Nonlocal Spin Valves on Silicon Nitride Membranes*

Nonlocal spin valves (NLSVs) have the unique capability to separate charge and spin currents, and thus are an important tool for both applied and fundamental research in nanomagnetism.[1,2] Previous research shows that changes to the composition of the NLSV substrate can have a marked effect on the background nonlocal resistance by changing the substrate thermal conductance.[3] Our research demonstrates enhancement of non-local spin resistance by the anomalous Nernst effect (ANE) and dramatically lowered thermal conductance in NLSVs fabricated on SiN membranes.[4,5]

We present refined values as low as 0.27 for the Nernst coefficient of permalloy as determined by 2D finite-element analysis of Py/Al NLSVs, where the thermal gradient is confined to two dimensions by the membrane-supported construction. We also present new insight into thermal spin injection effects other than ANE, including thermally-assisted electrical spin injection.

[1] Jedema, et al. Nature 410, 345 (2001)
[2] Ji, et al, APL 88, 052509 (2006)
[3] Kasai, et al. APL 104, 162410 (2014)
[4] Hojem, et al. (in preparation)
[5] Bennet, et al. (in preparation)