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

• We experimentally study the auto-oscillating spin wave modes in NiFe/β-W constriction-based spin Hall nano-oscillators versus bias current, in-plane applied field strength, and azimuthal angle. We observe two different spin wave modes in weak in-plane fields: a linear-like mode confined in the minima of the internal field near the edges of the nano-constriction with weak frequency dependencies on the bias current and the applied field angle, and 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 experimental data and reveals that the second mode is the spin wave bullet. In contrast to the linear-like mode, the bullet is (a) localized in the middle of the constriction and (b) shrinks with the bias current. Our results are important for the development of the field-free spintronic oscillators for the applications in microwave signal generation and neuromorphic computing.

Subject headings

NATURVETENSKAP  -- Fysik -- Den kondenserade materiens fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Condensed Matter Physics (hsv//eng)

Keyword

spin wave

nano-oscillators

SHNOs

spin Hall

in-plane field

Physics

Fysik

Publication and Content Type

vet (subject category)

ovr (subject category)