Field-Assisted Sub-Terahertz Spin Pumping and Auto-Oscillation in NiO

Abstract

Spin pumping converting sub-terahertz electromagnetic waves to DC spin currents has recently been demonstrated in antiferromagnets (AFMs) with easy-axis magnetic anisotropy. However, easy-plane AFMs such as NiO, which are easier to prepare experimentally, are considered to be bad candidates for spin pumping because the Néel vector oscillation is linearly polarized, placing a major restriction on the material choice for practical applications. Through a case study of NiO, we show that an applied magnetic field below the spin-flop transition can substantially modify the polarization of the resonance eigenmodes, which enables coherent sub-terahertz spin pumping as strong as that in easy-axis AFMs. In addition, we find that an applied magnetic field can significantly reduce the threshold of Néel vector auto-oscillation triggered by spin-transfer torques. These prominent field-assisted effects can greatly facilitate spintronic device engineering in the sub-terahertz frequency regime.

References in corpus (10)

• Antiferromagnetic spintronics
• Spin battery operated by ferromagnetic resonance
• Spin pumping and spin-transfer torques in antiferromagnets
• Subterahertz spin pumping from an insulating antiferromagnet
• Terahertz Antiferromagnetic Spin Hall Nano-Oscillator
• Ultrafast Switching of Antiferromagnets via Spin-transfer Torque
• Room temperature antiferromagnetic resonance and inverse spin-Hall voltage in canted antiferromagnets
• Spin Pumping of an Easy-Plane Antiferromagnet Enhanced by Dzyaloshinskii-Moriya Interaction
• Spin Pumping and Inverse Spin Hall Voltages from Dynamical Antiferromagnets
• Electrically tunable detector of THz-frequency signals based on an antiferromagnet