Role of spin mixing conductance in determining thermal spin pumping near the ferromagnetic phase transition in EuO1-x and La2NiMnO6

Mallick, Kingshuk and Wagh, Aditya A and Ionescu, Adrian and Barnes, Crispin H W and Kumar, P S Anil (2019) Role of spin mixing conductance in determining thermal spin pumping near the ferromagnetic phase transition in EuO1-x and La2NiMnO6. In: PHYSICAL REVIEW B, 100 (22).

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Abstract

We present a comprehensive study of the temperature (T) dependence of the longitudinal spin Seebeck effect (LSSE) in Pt/EuO1-x and Pt/La2NiMnO6 (LNMO) hybrid structures across their Curie temperatures (T-c). Both systems host ferromagnetic interaction below T-c, and hence present optimal conditions for testing magnon spin current based theories against ferrimagnetic yttrium iron garnet. Notably, we observe an anomalous Nernst effect generated voltage in bare EuO1-x, however, we find LSSE predominates the thermal signals in the bilayers with Pt. The T dependence of the LSSE in small T range near T-c could be fitted to a power law of the form (T-c- T)(p). The derived critical exponent P was verified for different methods of LSSE representation and sample crystallinity. The results are explained based on the magnon-driven thermal spin pumping mechanism that relates the T dependence of LSSE to the spin mixing conductance (G(mix)) at the heavy metal/ferromagnet interface, which in turn is known to vary inaccordance with the square of the spontaneous magnetization (M-s). Additionally, the T dependence of the real part of G(mix) derived from spin Hall magnetoresistance measurements at different temperatures for the Pt/LNMO structure further establishes the interdependence.

Item Type:	Journal Article
Publication:	PHYSICAL REVIEW B
Publisher:	AMER PHYSICAL SOC
Additional Information:	Copyright of this article belongs to AMER PHYSICAL SOC
Keywords:	SILICON; ORIGIN
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	06 Jan 2020 10:34
Last Modified:	06 Jan 2020 10:34
URI:	http://eprints.iisc.ac.in/id/eprint/64087

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