Magnon contribution to unidirectional spin Hall magnetoresistance

Abstract

We develop a model for the magnonic contribution to the unidirectional spin Hall magnetoresistance (USMR) of heavy metal/ferromagnetic insulator bilayer films. We show that diffusive transport of Holstein-Primakoff magnons leads to an accumulation of spin near the bilayer interface, giving rise to a magnoresistance which is not invariant under inversion of the current direction. Unlike the electronic contribution described by Zhang and Vignale [Phys. Rev. B 94, 140411 (2016)], which requires an electrically conductive ferromagnet, the magnonic contribution can occur in ferromagnetic insulators such as yttrium iron garnet. We show that the magnonic USMR is, to leading order, cubic in the spin Hall angle of the heavy metal, as opposed to the linear relation found for the electronic contribution. We estimate that the maximal magnonic USMR in Pt|YIG bilayers is on the order of $10^{-8}$, but may reach values of up to $10^{-5}$ if the magnon gap is suppressed, and can thus become comparable to the electronic contribution in, e.g., Pt|Co. We show that the magnonic USMR at a finite magnon gap may be enhanced by an order of magnitude if the magnon diffusion length is decreased to a specific optimal value that depends on various system parameters.

arXiv comment9 pages, 7 figures

References in corpus (18)

• Enhanced Gilbert Damping in Thin Ferromagnetic Films
• Theory of spin Hall magnetoresistance
• Role of transparency of platinum-ferromagnet interface in determining intrinsic magnitude of spin Hall effect
• Unidirectional spin Hall magnetoresistance in ferromagnet/normal metal bilayers
• Magnon spin transport driven by the magnon chemical potential in a magnetic insulator
• Large Unidirectional Magnetoresistance in a Magnetic Topological Insulator
• Magnon, phonon and electron temperature profiles and the spin Seebeck effect in magnetic insulator/normal metal hybrid structures
• Magnon Mediated Electric Current Drag Across a Ferromagnetic Insulator Layer
• Spin convertance at magnetic interfaces
• Electronic Pumping of Quasiequilibrium Bose-Einstein Condensed Magnons
• Origins of the unidirectional spin Hall magnetoresistance in metallic bilayers
• Theory of unidirectional spin Hall magnetoresistance in heavy-metal/ferromagnetic-metal bilayers
• Magnetoresistance of heavy and light metal/ferromagnet bilayers
• Interfacial Spin and Heat Transfer between Metals and Magnetic Insulators
• Theory of spin Hall effect
• Anisotropy effects on the magnetic excitations of a ferromagnetic monolayer below and above the Curie temperature
• Spin superfluidity and long-range transport in thin-film ferromagnets
• Thickness dependence of unidirectional spin-Hall magnetoresistance in metallic bilayers

Cited by in corpus (19)

• Observation of nuclear-spin Seebeck effect
• Unidirectional orbital magnetoresistance in light metal/ferromagnet bilayers
• Paramagnetic spin Hall magnetoresistance
• Microscopic Theory of the Spin Hall Magnetoresistance
• Large anomalous unidirectional magnetoresistance in a single ferromagnetic layer
• Nonlinear longitudinal and transverse magnetoresistances due to current-induced magnon creation-annihilation processes
• Disentangle magnon magnetoresistance from anisotropic and spin Hall magnetoresistance in NiFe/Pt bilayers
• Estimation of spin-orbit torques in the presence of current-induced magnon creation and annihilation
• Nonreciprocal Ballistic Transport in Asymmetric Bands
• Proximity-induced nonlinear magnetoresistances on topological insulators
• Spin-Hall magnetoresistance in quasi-two-dimensional antiferromagnetic insulator/metal bilayer systems
• Frequency-dependent Phonon-mediated Unidirectional Magnetoresistance in a Metal on an Insulator with Highly Nonequilibrium Magnons
• Magnon-mediated electric current drag and nonlocal spin-Peltier effect in the ac regime
• Theory of nonlinear magnetoelectric transport effects in normal-metal $-$ magnetic-insulator heterostructures
• Unidirectional spin Hall magnetoresistance and spin-orbit torques in HM${}_1$/Co/HM${}_2$ trilayer systems
• Fluctuation theorem for spin transport at insulating ferromagnetic junctions
• Theory of unidirectional magnetoresistance and nonlinear Hall effect
• Roles of Electron-Magnon Cross Diffusion in Unidirectional Magnetoresistance of Metallic Magnetic Bilayers
• Asymmetric magnetoresistance in 3$d$-5$d$ based La${}_{0.67}$Ca${}_{0.33}$MnO${}_3$/SrIrO${}_3$ bilayer: The role of unidirectional anisotropy