Anomalous Nernst effect in epitaxial Fe and FexNi1-x alloy thin films

L Ma,M Tang,H Zhao,H L Yang,N Tian,H R Fu,C Y You,Y Zhang,Z Shi

doi:10.1063/1.5079857

Abstract

The anomalous Nernst effect (ANE) is investigated experimentally in epitaxial fcc FexNi1-x (0≤x≤0.55) alloy thin films and bcc Fe thin film grown on MgO (001) substrates. The ANE measurements were performed at room temperature for various temperature gradients perpendicular to the film plane. The anomalous Nernst efficiency was indirectly characterized by the factor νN. It is found that both the ANE voltage VANE and the factor νN increase with raising the composition of Fe from 0 to 0.55, due to the presence of more abundant band structures. Moreover, the VANE and νN factor in bcc Fe thin film change sign and decrease sharply in magnitude compared to that of fcc FexNi1-x thin films, indicating that the tuning effects of the band filling near Fermi surface on ANE. The present results will facilitate the theoretical studies of ANE and provide means of manipulating ANE for technological application.

Highlights

With the prominent advantages of electron spin and magnetic order, the spin caloritronics1 plays an important role in improving the existing thermoelectric devices
Such as spin Seebeck effect2,3 and spin Nernst effect4,5 which are based on non-magnetic heavy normal metal/ferromagnetic heterostructures can realize the conversion between spin current and charge current in the presence of heat flow
In anomalous Nernst effect (ANE), an electric field can be generated in the cross product direction between the magnetization and temperature gradient in the ferromagnetic material

Summary

Introduction

With the prominent advantages of electron spin and magnetic order, the spin caloritronics1 plays an important role in improving the existing thermoelectric devices. The Fermi level can be continuously tuned by changing the Fe/Ni composition, whereas the impact from SOC can scitation.org/journal/adv be ignored.26 The ANE in fcc FeNi alloy thin films was found to be continuously regulated when the Fermi level shifts due to the band filling effect.

Results

Conclusion