skip to main content

Title: Spin transfer torque generated magnetic droplet solitons (invited)

We present recent experimental and numerical advancements in the understanding of spin transfer torque generated magnetic droplet solitons. The experimental work focuses on nano-contact spin torque oscillators (NC-STOs) based on orthogonal (pseudo) spin valves where the Co fixed layer has an easy-plane anisotropy, and the [Co/Ni] free layer has a strong perpendicular magnetic anisotropy. The NC-STO resistance and microwave signal generation are measured simultaneously as a function of drive current and applied perpendicular magnetic field. Both exhibit dramatic transitions at a certain current dependent critical field value, where the microwave frequency drops 10 GHz, modulation sidebands appear, and the resistance exhibits a jump, while the magnetoresistance changes sign. We interpret these observations as the nucleation of a magnetic droplet soliton with a large fraction of its magnetization processing with an angle greater than 90°, i.e., around a direction opposite that of the applied field. This interpretation is corroborated by numerical simulations. When the field is further increased, we find that the droplet eventually collapses under the pressure from the Zeeman energy.
Authors:
 [1] ;  [2] ;  [1] ;  [2] ;  [3] ;  [1] ;  [2] ; ; ;  [4] ;  [1] ;  [5] ;  [4] ;  [6] ;  [7] ;  [8] ;  [1] ;  [2] ;  [2]
  1. Materials Physics, School of ICT, Royal Institute of Technology, Electrum 229, 164 40 Kista (Sweden)
  2. (Sweden)
  3. (Iran, Islamic Republic of)
  4. Department of Physics, University of Gothenburg, 412 96 Gothenburg (Sweden)
  5. (LNT), Vietnam National University - Ho Chi Minh City (VNU-HCM), Ho Chi Minh City (Viet Nam)
  6. (India)
  7. Devices and Circuits, School of ICT, KTH Royal Institute of Technology, Electrum 229, 164 40 Kista (Sweden)
  8. Department of Mathematics, North Carolina State University, Raleigh, North Carolina 27695 (United States)
Publication Date:
OSTI Identifier:
22273578
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 17; Conference: 55. annual conference on magnetism and magnetic materials, Atlanta, GA (United States), 14-18 Nov 2010; Other Information: (c) 2014 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; COMPUTERIZED SIMULATION; CRITICAL FIELD; DROPLETS; GHZ RANGE; LAYERS; MAGNETIZATION; MAGNETORESISTANCE; MICROWAVE RADIATION; OSCILLATORS; SOLITONS; SPIN; TORQUE; VALVES; ZEEMAN EFFECT