A1 Journal article (refereed)
Spin Pumping and Torque Statistics in the Quantum Noise Limit (2017)

Virtanen, P., & Heikkilä, T. (2017). Spin Pumping and Torque Statistics in the Quantum Noise Limit. Physical Review Letters, 118(23), Article 237701. https://doi.org/10.1103/PhysRevLett.118.237701

JYU authors or editors

Virtanen, Pauli
Heikkilä, Tero

Publication details

All authors or editors: Virtanen, Pauli; Heikkilä, Tero

Journal or series: Physical Review Letters

ISSN: 0031-9007

eISSN: 1079-7114

Publication year: 2017

Volume: 118

Issue number: 23

Article number: 237701

Publisher: American Physical Society

Publication country: United States

Publication language: English

DOI: https://doi.org/10.1103/PhysRevLett.118.237701

Publication open access: Other way freely accessible online

Publication channel open access:

Publication is parallel published (JYX): https://jyx.jyu.fi/handle/123456789/54480

Web address where publication is available: https://arxiv.org/abs/1609.04619

Abstract

We analyze the statistics of charge and energy currents and spin torque in a metallic nanomagnet coupled to a large magnetic metal via a tunnel contact. We derive a Keldysh action for the tunnel barrier, describing the stochastic currents in the presence of a magnetization precessing with the rate Ω. In contrast to some earlier approaches, our result is valid for an arbitrary ratio of ℏΩ/kBT. We illustrate the use of the action by deriving spintronic fluctuation relations, the quantum limit of pumped current noise, and consider the fluctuations in two specific cases: the situation with a stable precession of magnetization driven by spin transfer torque, and the torque-induced switching between the minima of a magnetic anisotropy. The quantum corrections are relevant when the precession rate exceeds the temperature T, i.e., for ℏΩ≳kBT.

Keywords: nanotechnology; quantum mechanics; computational fluid dynamics; magnetism

Free keywords: spin pumping; torque statistics; quantum noise limit

Fields of science: