Effective suppression of thermoelectric voltage in nonlocal spin-valve measurement

Abstract

We demonstrate that the background signal in the nonlocal spin-valve measurement can be sufficiently suppressed by optimizing the electrode design of the lateral spin valve. A relatively long length scale of heat propagation produces spin-independent thermoelectric signals under the combination of the Peltier and Seebeck effects. These unfavorable signals can be reduced by mixing the Peltier effects in two transparent ferromagnetic/nonmagnetic junctions. Proper understanding of the contribution from the heat current in no spin-current area is a key for effective reduction of the spin-independent background signal.

Charge-induced artifacts in non-local spin transport measurements: How to prevent spurious voltage signals

“…It is well-documented that thermo-electric and even magneto-thermo-electric effects can cause non-local charge signals via a combination of Joule heating, the Peltier effect, the Seebeck effect, the Ettingshausen effect, or the Nernst effect [45,[47][48][49][50][51][52][53]. The heat that is generated by the flow of charge carriers between the injection electrodes I + and I − (Fig.…”

“…This temperature gradient then results in a differential voltage V T via e.g. the Seebeck or Nernst effect [47][48][49][50][51][52][53].…”

“…Because of the inherent nature of thermoelectric voltages, we are not aware of measurement methods that can reduce their contribution after device fabrication. A suppression of these spurious signals can only occur by design choices during the fabrication process, like the design of electrodes that may function as heat sinks, the heat conductivity of the underlying substrate, or the design of the I + and I − electrodes in such a way that their respective Peltier effects cancel each other to some extent [45,52,53].…”