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Title: Tunable Mode Coupling in Nanocontact Spin-Torque Oscillators

Recent experiments on spin-torque oscillators have revealed interactions between multiple magneto-dynamic modes, including mode coexistence, mode hopping, and temperature-driven crossover between modes. The initial multimode theory indicates that a linear coupling between several dominant modes, arising from the interaction of the subdynamic system with a magnon bath, plays an essential role in the generation of various multimode behaviors, such as mode hopping and mode coexistence. In this work, we derive a set of rate equations to describe the dynamics of coupled magneto-dynamic modes in a nanocontact spin-torque oscillator. Here, expressions for both linear and nonlinear coupling terms are obtained, which allow us to analyze the dependence of the coupled dynamic behaviors of modes on external experimental conditions as well as intrinsic magnetic properties. For a minimal two-mode system, we further map the energy and phase difference of the two modes onto a two-dimensional phase space and demonstrate in the phase portraits how the manifolds of periodic orbits and fixed points vary with an external magnetic field as well as with the temperature.
Authors:
 [1] ;  [2] ;  [3]
  1. Univ. of Missouri, Columbia, MO (United States); Argonne National Lab. (ANL), Lemont, IL (United States)
  2. Univ. of Colorado, Boulder, CO (United States); Chalmers Univ. of Technology, Gothenburg (Sweden)
  3. Argonne National Lab. (ANL), Lemont, IL (United States); Northwestern-Argonne Institute of Science and Technology, Evanston, IL (United States); The Univ. of Chicago, Chicago, IL (United States)
Publication Date:
Grant/Contract Number:
AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Physical Review Applied
Additional Journal Information:
Journal Volume: 8; Journal Issue: 1; Journal ID: ISSN 2331-7019
Publisher:
American Physical Society (APS)
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
Swedish Research Council (SRC); National Science Foundation (NSF); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22), Materials Sciences and Engineering Division; USDOE
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS
OSTI Identifier:
1393204
Alternate Identifier(s):
OSTI ID: 1373130