Microscopic derivation of magnon spin current in a topological insulator/ferromagnet heterostructure

Abstract

We investigate a spin-electricity conversion effect in a topological insulator/ferromagnet heterostructure. In the spin-momentum-locked surface state, an electric current generates nonequilibrium spin accumulation, which causes a spin-orbit torque that acts on the ferromagnet. When spins in the ferromagnet are completely parallel to the accumulated spin, this spin-orbit torque is zero. In the presence of spin excitations, however, a coupling between magnons and electrons enables us to obtain a nonvanishing torque. In this paper, we consider a model of the heterostructure in which a three-dimensional magnon gas is coupled with a two-dimensional massless Dirac electron system at the interface. We calculate the torque induced by an electric field, which can be interpreted as a magnon spin current, up to the lowest order of the electron-magnon interaction. We derive the expressions for high and low temperatures and estimate the order of magnitude of the induced spin current for realistic materials at room temperature.

9 pages, 4 figures

References in corpus (6)

• Current induced electron spin polarization in strained semiconductors
• Fermi level dependent charge-to-spin current conversion by Dirac surface state of topological insulators
• Surface quantized anomalous Hall current and magneto-electric effect in magnetically disordered topological insulators
• Large Unidirectional Magnetoresistance in a Magnetic Topological Insulator
• Surface state dominated spin-charge current conversion in topological insulator/ferromagnetic insulator heterostructures
• Enhanced spin Seebeck effect signal due to spin-momentum locked topological surface states

Cited by in corpus (13)

• Theory for spin torque in Weyl semimetal with magnetic texture
• First-principles quantum transport modeling of spin-transfer and spin-orbit torques in magnetic multilayers
• Magnon-driven chiral charge and spin pumping and electron-magnon scattering from time-dependent quantum transport combined with atomistic spin dynamics theory
• Quantum many-body states and Green functions of nonequilibrium electron-magnon systems: Localized spin operators vs. their mapping to Holstein-Primakoff bosons
• Non-linear antidamping spin-orbit torque originating from intra-band transport on the warped surface of a topological insulator
• Influence of spin-orbit and spin-Hall effects on the spin Seebeck current beyond linear response
• Spin torque and persistent currents caused by percolation of topological surface states
• Persistent currents and spin torque caused by percolated quantum spin Hall state
• Theory of Cross-correlated Electron-Magnon Transport Phenomena: Case of Magnetic Topological Insulator
• Voltage-control of damping constant in magnetic-insulator/topological-insulator bilayers
• Theory of Phason Drag Effect on Thermoelectricity
• Proximity-induced zero-energy states indistinguishable from topological edge states
• Microscopic theory of electrically induced spin torques in magnetic Weyl semimetals