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Title: Mode-coupling mechanisms in nanocontact spin-torque oscillators

Abstract

Spin torque oscillators (STOs) are devices that allow for the excitation of a variety of magneto-dynamical modes at the nanoscale. Depending on both external conditions and intrinsic magnetic properties, STOs can exhibit regimes of mode-hopping and even mode coexistence. Whereas mode hopping has been extensively studied in STOs patterned as nanopillars, coexistence has been only recently observed for localized modes in nanocontact STOs (NC-STOs) where the current is confined to flow through a NC fabricated on an extended pseudo spin valve. We investigate the physical origin of the mode coupling mechanisms favoring coexistence, by means of electrical characterization and a multi-mode STO theory. Two coupling mechanisms are identified: (i) magnon mediated scattering and (ii) inter-mode interactions. These mechanisms can be physically disentangled by fabricating devices where the NCs have an elliptical cross-section. Furthermore, the generation power and linewidth from such devices are found to be in good qualitative agreement with the theoretical predictions, as well as provide evidence of the dominant mode coupling mechanisms.

Authors:
 [1];  [2];  [3];  [4];  [1]
  1. Univ.of Gothenburg (Sweden). Physics Dept. ; NanOsc AB, Kista (Sweden)
  2. Univ.of Gothenburg (Sweden). Physics Dept.
  3. Argonne National Lab. (ANL), Argonne, IL (United States). Materials Science Division; Northwestern-Argonne Inst. for Science and Engineering, Evanston, IL (United States)
  4. Univ.of Gothenburg (Sweden). Physics Dept. ; NanOsc AB, Kista (Sweden); Royal Inst. of Technology, Kista (Sweden). School of ICT
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); European Commission (EC); Swedish Foundation for Strategic Research (SSF); Swedish Research Council (SRC)
OSTI Identifier:
1357006
Alternate Identifier(s):
OSTI ID: 1180992
Grant/Contract Number:  
AC02-06CH11357
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physical Review. B, Condensed Matter and Materials Physics
Additional Journal Information:
Journal Volume: 91; Journal Issue: 10; Journal ID: ISSN 1098-0121
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Iacocca, Ezio, Dürrenfeld, Philipp, Heinonen, Olle, Åkerman, Johan, and Dumas, Randy K. Mode-coupling mechanisms in nanocontact spin-torque oscillators. United States: N. p., 2015. Web. doi:10.1103/PhysRevB.91.104405.
Iacocca, Ezio, Dürrenfeld, Philipp, Heinonen, Olle, Åkerman, Johan, & Dumas, Randy K. Mode-coupling mechanisms in nanocontact spin-torque oscillators. United States. doi:10.1103/PhysRevB.91.104405.
Iacocca, Ezio, Dürrenfeld, Philipp, Heinonen, Olle, Åkerman, Johan, and Dumas, Randy K. Wed . "Mode-coupling mechanisms in nanocontact spin-torque oscillators". United States. doi:10.1103/PhysRevB.91.104405. https://www.osti.gov/servlets/purl/1357006.
@article{osti_1357006,
title = {Mode-coupling mechanisms in nanocontact spin-torque oscillators},
author = {Iacocca, Ezio and Dürrenfeld, Philipp and Heinonen, Olle and Åkerman, Johan and Dumas, Randy K.},
abstractNote = {Spin torque oscillators (STOs) are devices that allow for the excitation of a variety of magneto-dynamical modes at the nanoscale. Depending on both external conditions and intrinsic magnetic properties, STOs can exhibit regimes of mode-hopping and even mode coexistence. Whereas mode hopping has been extensively studied in STOs patterned as nanopillars, coexistence has been only recently observed for localized modes in nanocontact STOs (NC-STOs) where the current is confined to flow through a NC fabricated on an extended pseudo spin valve. We investigate the physical origin of the mode coupling mechanisms favoring coexistence, by means of electrical characterization and a multi-mode STO theory. Two coupling mechanisms are identified: (i) magnon mediated scattering and (ii) inter-mode interactions. These mechanisms can be physically disentangled by fabricating devices where the NCs have an elliptical cross-section. Furthermore, the generation power and linewidth from such devices are found to be in good qualitative agreement with the theoretical predictions, as well as provide evidence of the dominant mode coupling mechanisms.},
doi = {10.1103/PhysRevB.91.104405},
journal = {Physical Review. B, Condensed Matter and Materials Physics},
number = 10,
volume = 91,
place = {United States},
year = {Wed Mar 11 00:00:00 EDT 2015},
month = {Wed Mar 11 00:00:00 EDT 2015}
}

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