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Title: Heteroclinic tangle phenomena in nanomagnets subject to time-harmonic excitations

Magnetization dynamics in uniformly magnetized nanomagnets excited by time-harmonic (AC) external fields or spin-polarized injected currents is considered. The analysis is focused on the behaviour of the AC-excited dynamics near saddle equilibria. It turns out that this dynamics has a chaotic character at moderately low power level. This chaotic and fractal nature is due to the phenomenon of heteroclinic tangle which is produced by the combined effect of AC-excitations and saddle type dynamics. By using the perturbation technique based on Melnikov function, analytical formulas for the threshold AC excitation amplitudes necessary to create the heteroclinic tangle are derived. Both the cases of AC applied fields and AC spin-polarized injected currents are treated. Then, by means of numerical simulations, we show how heteroclinic tangle is accompanied by the erosion of the safe basin around the stable regimes.
Authors:
; ;  [1] ; ;  [2] ;  [3] ;  [4]
  1. DIETI, Università di Napoli “Federico II,” I-80125 Napoli (Italy)
  2. Istituto Nazionale di Ricerca Metrologica, I-10135 Torino (Italy)
  3. Dip. di Ingegneria, Università di Napoli “Parthenope,” I-80143 Napoli (Italy)
  4. ECE Department and UMIACS, University of Maryland, College Park, Maryland 20742 (United States)
Publication Date:
OSTI Identifier:
22409975
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 17; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CHAOS THEORY; COMPUTERIZED SIMULATION; EQUILIBRIUM; EROSION; EXCITATION; FRACTALS; MAGNETIC MATERIALS; MAGNETIZATION; NANOSTRUCTURES; SPIN ORIENTATION