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)