Authors:	Baldrati, Lorenzo Schneider, Christoph Niizeki, T. Ramos, R. Cramer, Joel Ross, Andrew Saitoh, E. Kläui, Mathias
Title:	Spin transport in multilayer systems with fully epitaxial NiO thin films
Online publication date:	20-Aug-2019
Year of first publication:	2018
Language:	english
Abstract:	We report the generation and transport of thermal spin currents in fully epitaxial γ−Fe2O3/NiO(001)/Pt and Fe3O4/NiO(001)/Pt trilayers. A thermal gradient, perpendicular to the plane of the sample, generates a magnonic spin current in the ferrimagnetic maghemite (γ−Fe2O3) and magnetite (Fe3O4) thin films by means of the spin Seebeck effect. The spin current propagates across the epitaxial, antiferromagnetic insulating NiO layer, before being detected in the Pt layer by the inverse spin Hall effect. The transport of the spin signal is studied as a function of the NiO thickness, temperature, and ferrimagnetic material where the spin current is generated. In epitaxial NiO grown on maghemite, the spin Seebeck signal decays exponentially as a function of the NiO thickness, with a spin-diffusion length for thermally generated magnons of λMSDL=1.6±0.2nm (where MSDL is mean spin-diffusion length), largely independent of temperature. We see no enhancement of the spin-current signal as previously reported for certain temperatures and thicknesses of the NiO. In epitaxial NiO grown on magnetite, the temperature-averaged spin-diffusion length is λMSDL=3.8±0.3nm, and we observe an enhancement of the spin signal when the NiO thickness is 0.8 nm, demonstrating that the growth conditions dramatically affect the spin-transport properties of the NiO even for full epitaxial growth. In contrast to theoretical predictions for coherent spin transport, we do not see vastly different spin-diffusion lengths between epitaxial and polycrystalline NiO layers.
DDC:	530 Physik 530 Physics
Institution:	Johannes Gutenberg-Universität
Department:	FB 08 Physik, Mathematik u. Informatik
Place:	Mainz
ROR:	https://ror.org/023b0x485
DOI:	http://doi.org/10.25358/openscience-195
URN:	urn:nbn:de:hebis:77-publ-591892
Version:	Accepted version
Publication type:	Zeitschriftenaufsatz
License:	In Copyright
Information on rights of use:	https://rightsstatements.org/vocab/InC/1.0/
Journal:	Physical review : B 98 1
Pages or article number:	Art. 014409
Publisher:	APS
Publisher place:	College Park, Md.
Issue date:	2018
ISSN:	2469-9969 1095-3795
Publisher URL:	http://dx.doi.org/10.1103/PhysRevB.98.014409
Publisher DOI:	10.1103/PhysRevB.98.014409
Appears in collections:	JGU-Publikationen