Spin Seebeck effect (SSE) was investigated in Heusler compound Co 2MnSi (CMS) and ferromagnetic binary alloy Ni 80Fe 20 (Py) thin films deposited on MgO substrates at different ambient temperatures, T = 30 K to 295 K, by maintaining a finite temperature gradient along the film plane. Low temperature enhancement of voltage signal and a peak around T = 70 K were detected in a Pt wire placed on the higher temperature end of CMS (or Py) film. It has been found that the low temperature enhancement was dominated by a thermal artifact, which was generated by the anomalous Nernst effect with an additional perpendicular temperature gradient across the film plane. The remarkable mismatch between thermal conductivities of MgO and CMS (or Py) at low temperatures is considered to give rise to the perpendicular temperature gradient causing the thermal artifact. We showed that consideration of thermal conductivity matching between thin film and substrate is essential for performing experiments of SSE correctly; moreover, the observation of SSE could be realized only when minimization of the thermal artifact is possible.
ASJC Scopus subject areas
- Physics and Astronomy(all)