Anisotropic Magnetothermopower in Ferromagnetic Thin Films

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Venue:OE134, MMC

Abstract

Magnetothermal phenomena have become of interest in pursuit of phenomena such as the Spin Seebeck Effect [1, 2]. However, there has been credible evidence that thermal gradients along the surface normal have led to spurious results originating from the Anomalous Nernst Effect [3]. Based on such observations, it has been suggested that eliminating these unintentional thermal gradients may not be possible without completely [3] or virtually eliminating the substrate [4, 5]. In this talk, I will report that edge mounting the substrate to the thermal baths and placing the electrical contacts away from the ferromagnet effectively reduces these unwanted thermal gradients and enables the clear observation of the Anisotropic Magnetothermopower in several film/substrate combinations, with no measurable contribution from Anomalous Nernst Effect. Applying this work to samples with ferromagnets coupled to single crystal substrates may thus enable pure Spin Seebeck Effect measurements in the in-plane geometry.

[1] K. Uchida, S. Takahashi, K. Harii, J. Ieda, W. Koshibae, K. Ando, S. Maekawa, and E. Saitoh. Observation of spin seebeck effect. Nature, 455:778–781, Aug 2008.

[2] Jiang Xiao, Gerrit E. W. Bauer, Ken-chi Uchida, Eiji Saitoh, and Sadamichi Maekawa. Theory of magnon-driven spin seebeck effect. Phys. Rev. B, 81:214418, Jun 2010.

[3] S. Y. Huang, W. G.Wang, S. F. Lee, J. Kwo, and C. L. Chien. Intrinsic spin-dependent thermal transport. Phys. Rev. Lett., 107:216604, Nov 2011.

[4] A. D. Avery, M. R. Pufall, and B. L. Zink. Determining the planar nernst effect from magnetic field-dependent thermopower and resistance in nickel and permalloy thin films. Phys. Rev. B, 86:184408, Nov 2012.

[5] A. D. Avery, M. R. Pufall, and B. L. Zink. Observation of the planar nernst effect in permalloy and nickel thin films with in-plane thermal gradients. Phys. Rev. Lett., 109:196602, Nov 2012.

Biography

Casey W. Miller is presently Associate Professor of Physics at the University of South Florida in Tampa, where he studies nanoscale magnetism and related devices. He is Director of the new APS-Bridge Site at USF, as well as Associate Director of Physics Graduate Studies. He graduated summa cum laude from Wittenberg University in 1999 with University and Physics Departmental Honors and, where he was also elected to ΦΒΚ. He earned his PhD from the University of Texas at Austin in 2003, notably earning the Department’s Best Dissertation Award for work combining Magnetic Resonance Imaging with Scanning Probe Microscopy. He joined USF in 2007 after completing a post-doctoral fellowship at the University of California, San Diego, where he worked on spin-dependent tunneling.