Probing surface magnetic anisotropy via Longitudinal Spin Seebeck Effect on spinels*

Spintronics is an emergent field due to the promising applications of spin-dependent charge currents[1]. However, there are some limitations regarding the spin-mixing conductance at the interface of the non-magnetic metal (NM)/ferromagnetic meal (FM). Therefore, it is paramount the study of the role of the magnetic properties at this NM/FM interface. We have studied the Longitudinal Spin Seebeck Effect (LSSE) in Pt (NM)/spinel (FM) interfaces. We have grown two different spinels: CoFe₂O₄ (CFO) and MnFe₂O₄ (MFO) by Polymer Assisted Deposition (PAD). Previously studies have confirmed the existence of an intrinsic surface layer with reduced magnetic anisotropy (soft layer), whose relative thickness can be tuned within the growth[2], on CFO films. In this paper, we probe the existence of the mentioned soft layer contribution in the total magnetic anisotropy by controlling the thermal gradient across the CFO film whereas there is no magnetic anisotropy variation across the MFO film.
References
[1] Spin Current, edited by S. Maekawa, S. O. Valenzuela, E. Saitoh, and T. Kimura (Oxford University Press, 2012).
[2] F. Rigato, J. Geshev, V. Skumryev, and J. Fontcuberta, Journal of Applied Physics 106, 113924 (2009).