6,421 research outputs found
Terahertz Antiferromagnetic Spin Hall Nano-Oscillator
We consider the current-induced dynamics of insulating antiferromagnets in a
spin Hall geometry. Sufficiently large in-plane currents perpendicular to the
N\'{e}el order trigger spontaneous oscillations at frequencies between the
acoustic and the optical eigenmodes. The direction of the driving current
determines the chirality of the excitation. When the current exceeds a
threshold, the combined effect of spin pumping and current-induced torques
introduces a dynamic feedback that sustains steady-state oscillations with
amplitudes controllable via the applied current. The ac voltage output is
calculated numerically as a function of the dc current input for different
feedback strengths. Our findings open a route towards terahertz
antiferromagnetic spin-torque oscillators.Comment: 5+ pages, 4 figure
Interlayer Couplings Mediated by Antiferromagnetic Magnons
Collinear antiferromagnets (AFs) support two degenerate magnon excitations
carrying opposite spin polarizations, by which magnons can function as
electrons in various spin-related phenomena. In an insulating
ferromagnet(F)/AF/F trilayer, we explore the magnon-mediated interlayer
coupling by calculating the magnon thermal energy in the AF as a function of
the orientations of the Fs. The effect manifests as an interlayer exchange
interaction and a perpendicular magnetic anisotropy; they both depend on
temperature and the AF thickness. In particular, the exchange interaction turns
out to be antiferromagnetic at low temperatures and ferromagnetic at high
temperatures, whose magnitude can be eV for nanoscale
separations, allowing experimental verification.Comment: Physical Review Letters 121, 207202 (2018
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