Large Spin Hall Magnetoresistance in Antiferromagnetic <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:mi>α</mml:mi><mml:mtext>−</mml:mtext><mml:msub><mml:mi>Fe</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>3</mml:mn></mml:msub><mml:mo>/</mml:mo><mml:mi>Pt</mml:mi></mml:math> Heterostructures
Johanna Fischer, Matthias Althammer, Nynke Vlietstra, Hans Huebl, Sebastian T.B. Goennenwein, Rudolf Gross, Stephan Geprägs, Matthias Opel
Abstract
We investigate the spin Hall magnetoresistance (SMR) at room temperature in thin-film heterostructures of antiferromagnetic insulating (0001)-oriented $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{Fe}}_{2}{\mathrm{O}}_{3}$ (hematite) and $\mathrm{Pt}$. We measure their longitudinal and transverse resistivities while rotating an applied magnetic field of up to 17 T in three orthogonal planes. For out-of-plane magnetotransport measurements, we find indications for a multidomain antiferromagnetic configuration whenever the field is aligned along the film normal. For in-plane field rotations, we clearly observe a sinusoidal resistivity oscillation characteristic for the SMR due to a coherent rotation of the N\'eel vector. The maximum SMR amplitude of $0.25\mathrm{%}$ is, surprisingly, twice as high as for prototypical ferrimagnetic ${\mathrm{Y}}_{3}{\mathrm{Fe}}_{5}{\mathrm{O}}_{12}/\mathrm{Pt}$ heterostructures. The SMR effect saturates at much smaller magnetic fields than in comparable antiferromagnets, making the $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{Fe}}_{2}{\mathrm{O}}_{3}/\mathrm{Pt}$ system particularly interesting for room-temperature antiferromagnetic spintronic applications.