Enhanced spin transport in a ferrite having distributed energy barriers for exchange bias

Mallick, Kingshuk and Wagh, Aditya A and Kumar, P S Anil (2019) Enhanced spin transport in a ferrite having distributed energy barriers for exchange bias. In: JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS, 492 .

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Abstract

We observe an exchange bias at low temperatures in polycrystalline ferrimagnetic MgFe2O4 (MFO) films grown on Si(100), emerging from Antiferromagnetic (AFM)-like interactions at defect sites, concentrated predominantly at the grain boundaries. In this report, we show it is possible to utilize these AFM interactions to get enhanced spin transport utilizing the spin Seebeck effect (SSE). The temperature dependence of the SSE signal in two films with different defect densities allowed us to identify a unique temperature window for both films where an enhanced SSE signal was observed. Such enhancement has been reported in different Ferromagnet (FM)/AFM bilayer systems, but its observation in a single layer hosting both FM-AFM interactions makes our results attractive. Temperature dependent SQUID magnetometry revealed two distinct regions of strong and weak coupling for the FM-AFM interactions. The weak coupling region is characterized by a distribution of AFM energy barriers (Delta E), which can modify the spin conductance across the FM-AFM boundary and hence, affect the spin transport. Indeed, we find that the same functional form fits both the Delta E distribution and the SSE temperature evolution for both films. This study should aid in the understanding of SSE in the large class of polycrystalline materials with inherent growth induced defect densities and illustrate the significance of magnetically disordered phases in spin transport.

Item Type:	Journal Article
Publication:	JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
Publisher:	ELSEVIER
Additional Information:	copyright for this article belongs to ELSEVIER
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	07 Nov 2019 10:11
Last Modified:	07 Nov 2019 10:11
URI:	http://eprints.iisc.ac.in/id/eprint/63615

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