Mapping out the spin-wave modes of constriction-based spin Hall nano-oscillators in weak in-plane fields

Abstract

We experimentally study the auto-oscillating spin-wave modes in NiFe/$\beta -$W constriction-based spin Hall nano-oscillators as a function of bias current, in-plane applied field strength, and azimuthal field angle, in the low-field range of 40-80 mT. We observe two different spin-wave modes: i) a linear-like mode confined to the minima of the internal field near the edges of the nanoconstriction, with weak frequency dependencies on the bias current and the applied field angle, and ii) a second, lower frequency mode that has significantly higher threshold current and stronger frequency dependencies on both bias current and the external field angle. Our micromagnetic modeling qualitatively reproduces the experimental data and reveals that the second mode is a spin-wave bullet and that the SHNO mode hops between the two modes, resulting in a substantial increase in linewidths. In contrast to the linear-like mode, the bullet is localized in the middle of the constriction and shrinks with increasing bias current. Utilizing intrinsic frequency doubling at zero field angle we can reach frequencies above 9 GHz in fields as low as 40 mT, which is important for the development of low-field spintronic oscillators with applications in microwave signal generation and neuromorphic computing.

References in corpus (21)

• The design and verification of Mumax3
• Spin Hall effect
• Spin Torque Ferromagnetic Resonance Induced by the Spin Hall Effect
• Direct electronic measurement of the spin Hall effect
• Experimental observation of the spin-Hall effect in a two dimensional spin-orbit coupled semiconductor system
• Spin transfer torque devices utilizing the giant spin Hall effect of tungsten
• Measurement of the Spin-Transfer-Torque Vector in Magnetic Tunnel Junctions
• Spin-transfer-driven ferromagnetic resonance of individual nanomagnets
• Generation of coherent spin-wave modes in Yttrium Iron Garnet microdiscs by spin-orbit torque
• Nanowire Spin Torque Oscillator Driven by Spin Orbit Torques
• Spectral Characteristics of the Microwave Emission by the Spin Hall Nano-Oscillator
• Experimental evidence of self-localized and propagating spin wave modes in obliquely magnetized current-driven nanocontacts
• On the origin of magnetization auto-oscillations in constriction-based spin Hall nano-oscillators
• Large spin-wave bullet in a ferrimagnetic insulator driven by spin Hall effect
• CMOS compatible W/CoFeB/MgO spin Hall nano-oscillators with wide frequency tunability
• Decoherence and mode-hopping in a magnetic tunnel junction-based spin-torque oscillator
• Power and linewidth of propagating and localized modes in nanocontact spin-torque oscillators
• Generation linewidth of mode-hopping spin torque oscillators
• Spin-torque driven ferromagnetic resonance in a nonlinear regime
• Temperature dependence of linewidth in nano-contact based spin torque oscillators: effect of multiple oscillatory modes
• Homodyne-detected ferromagnetic resonance of in-plane magnetized nano-contacts: composite spin wave resonances and their excitation mechanism

Cited by in corpus (13)

• An Intrinsic Spin Orbit Torque Nano-Oscillator
• Energy-efficient W${}_{\text{100-x}}$Ta${}_{\text{x}}$/CoFeB/MgO spin Hall nano-oscillators
• Width dependent auto-oscillating properties of constriction based spin Hall nano-oscillators
• Hybrid spin Hall nano-oscillators based on ferromagnetic metal/ferrimagnetic insulator heterostructures
• Compositional effect on auto-oscillation behavior of Ni100-xFex/Pt spin Hall nano-oscillators
• Voltage control of frequency, effective damping and threshold current in nano-constriction-based spin Hall nano-oscillators
• Antiferromagnetic Bloch line driven by spin current as room-temperature analog of a fluxon in a long Josephson junction
• Origin of Nonlinear Damping due to Mode Coupling in Auto-Oscillatory Modes Strongly Driven by Spin-Orbit Torque
• Spin wave excitations in a nanowire spin-torque oscillator with perpendicular magnetic anisotropy
• Controllable excitation of quasi-linear and bullet modes in a spin-Hall nano-oscillator
• Effects of delayed feedback on the power spectrum of spin-torque nano-oscillators
• Spin orbit torque nano-oscillators by dipole field-localized spin wave modes
• Energy-efficient spin Hall nano-oscillators using near-compensated CoGd ferrimagnets