Spin transport in multilayer systems with fully epitaxial NiO thin films

Abstract

We report on the generation and transport of thermal spin currents in fully epitaxial γ-Fe${}_2$O${}_3$/NiO(001)/Pt and Fe${}_3$O${}_4$/NiO(001)/Pt trilayers. A thermal gradient, perpendicular to the plane of the sample, generates a magnonic spin current in the ferrimagnetic maghemite (γ-Fe${}_2$O${}_3$) and magnetite (Fe${}_3$O${}_4$) 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 λ${}_{MSDL}$ = $1.6\pm 0.2$ nm, largely independent on 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 λ${}_{MSDL}$ = $3.8\pm 0.3$ nm, 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.

References in corpus (19)

• Antiferromagnetic spintronics
• Antiferromagnetic spintronics
• Spin Caloritronics
• Spin Seebeck insulator
• Antiferromagnonic Spin Transport from Y${}_3$Fe${}_5$O${}_{12}$ into NiO
• Antiferromagnetic spin Seebeck Effect
• Thermoelectric generation based on spin Seebeck effects
• Enhancement of Thermally Injected Spin Current through an Antiferromagnetic Insulator
• Thermal generation of spin current in an antiferromagnet
• Determination of the origin of the spin Seebeck effect - bulk vs. interface effects
• Spin-current probe for phase transition in an insulator
• Observation of the spin Seebeck effect in epitaxial Fe3O4 thin films
• Thermal spin dynamics of yttrium iron garnet
• Transformation of spin current by antiferromagnetic insulators
• Origin of the thickness-dependent low-temperature enhancement of spin Seebeck effect in YIG films
• Spin Hall Magnetoresistance in a Canted Ferrimagnet
• Spin Seebeck effect through antiferromagnetic NiO
• Evidence for the role of the magnon energy relaxation length in the Spin Seebeck Effect
• Magnetic field control of the spin Seebeck effect

Cited by in corpus (6)

• Mechanism of Néel order switching in antiferromagnetic thin films revealed by magnetotransport and direct imaging
• Full angular dependence of the spin Hall and ordinary magnetoresistance in epitaxial antiferromagnetic NiO(001)/Pt thin films
• Propagation length of antiferromagnetic magnons governed by domain configurations
• Anisotropic long-range spin transport in canted antiferromagnetic orthoferrite YFeO${}_3$
• Antiferromagnetic insulatronics: spintronics in insulating 3d metal oxides with antiferromagnetic coupling
• Role of spin mixing conductance in determining thermal spin pumping near the ferromagnetic phase transition in EuO_{1-x} and La2NiMnO6