Title: Controllable vortex shedding from dissipative exchange flows in ferromagnetic channels

Abstract

Ferromagnetic channels subject to spin injection at one extremum sustain long-range coherent textures that carry spin currents known as dissipative exchange flows (DEFs). In the weak injection regime, spin currents carried by DEFs decay algebraically and extend through the length of the channel, a regime known as spin superfluidity. Similar to fluids, these structures are prone to phase slips that manifest as vortex-antivortex pairs. In this work, we numerically study vortex shedding from DEFs excited in a magnetic nanowire with a physical obstacle. Using micromagnetic simulations, we find regimes of laminar flow and vortex shedding as a function of obstacle position tunable by the spin injection sign and magnitude. Vortex-antivortex pairs translate forward (VF regime) or backward (VB regime) with respect to the detector's extremum, resulting in well-defined spectral features. Qualitatively similar results are obtained when temperature, anisotropy, and weak nonlocal dipole fields are included in the simulations. These results provide clear features associated with DEFs that may be detected experimentally in devices with nominally identical boundary conditions. Furthermore, our results suggest that obstacles can be considered as DEF control gates, opening an avenue to manipulate DEFs via physical defects.

Authors:

Iacocca, Ezio  ^[1]

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+ Show Author Affiliations

1. Northumbria University, Newcastle upon Tyne (United Kingdom)

Publication Date:

Thu Dec 03 00:00:00 EST 2020

Research Org.:

National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1852383

Grant/Contract Number:  

SC0017643

Resource Type:

Accepted Manuscript

Journal Name:

Physical Review. B

Additional Journal Information:

Journal Volume: 102; Journal Issue: 22; Journal ID: ISSN 2469-9950

Publisher:

American Physical Society (APS)

Country of Publication:

United States

Language:

English

Subject:

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; materials science; physics; magnetic texture; magnetic vortices; magnetism; nanowires; micromagnetic modeling