Mechanism Of Strong Enhancement Of Anomalous Nernst Effect In Fe By Ga Substitution

We have investigated the anomalous Nernst effect (ANE) in Fe1-xGax alloy films with different Ga atomic compositions (x = 0-0.44) deposited on MgO(001) single-crystalline substrates. We found that the magnitude of the ANE increases with increasing x up to x = 0.32 even though the saturation magnetization decreases with increasing x, suggesting a dominant contribution of the intrinsic mechanism on the observed ANE. The magnitude of the ANE reaches 2.4 mu V/K in bcc Fe0.68Ga0.32 film, which is two orders of magnitude greater than that of pure Fe film. The magnetotransport measurements and the first-principles calculations revealed that the large ANE in bcc Fe1-xGax is caused by the large transverse Peltier coefficient. The drastic enhancement of the transverse Peltier coefficient with increasing x can be attributed to small Fermi level tuning through the electron doping effect. Thus, we anticipate that our finding will provide a crucial piece of information to enhance the thermopower through the ANE.