Spin transfer torques by point-contact spin injection

T. Y. Chen, Y. Ji, Sunxiang Huang, C. L. Chien, M. D. Stiles

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Spin-transfer torques (STT) provides a new mechanism to alter the magnetic configurations in magnetic heterostructures, a feat previously only achieved by an external magnetic field. A current flowing perpendicular through a magnetic noncollinear spin structure can induce torques on the magnetization, depending on the polarity of the current. This is because an electron carries angular momentum, or spin, part of which can be transferred to the magnetic layer as a torque. A spin-polarized current of a substantial current density (e.g., 10 8 A/cm2) is required to observe the effect of the spin transfer torques. Consequently, switching by spin-polarized currents is often realized in small structures with sub-micron cross sections made by nanolithography. Here we demonstrate spin transfer torque effects using point-contact spin injection involving no lithography. In a continuous Co/Cu/Co trilayer, we have observed hysteretic reversal of sub-100 nm magnetic elements by spin injection through a metal tip both at low temperature and at room temperature. A small magnetic domain underneath the tip in the top Co layer can be manipulated to align parallel or anti-parallel to the bottom Co layer with a unique bias voltage. In an exchange-biased single ferromagnetic layer, we have observed a new form of STT effect which is the inverse effect of domain wall magnetoresistance effect rather than giant magnetoresistance effect. We further show that in granular solids, the STT effect that can be exploited to induce a large spin disorder when combined with a large magnetic field. As a result, we have obtained a spectacular MR effect in excess of 400%, the largest ever reported in any metallic systems.

Original languageEnglish (US)
Title of host publicationProceedings of SPIE - The International Society for Optical Engineering
Volume7398
DOIs
StatePublished - 2009
Externally publishedYes
EventSpintronics II - San Diego, CA, United States
Duration: Aug 2 2009Aug 5 2009

Other

OtherSpintronics II
CountryUnited States
CitySan Diego, CA
Period8/2/098/5/09

Fingerprint

Point contacts
Torque
torque
Injection
Contact
injection
Magnetoresistance
Magnetic fields
Nanolithography
Giant magnetoresistance
Magnetic domains
Angular momentum
Domain walls
Bias voltage
Chemical elements
Magnetic Field
Lithography
Heterojunctions
Magnetization
Antiparallel

Keywords

  • Current-induced switching
  • Magnetic granular solids
  • Point contact
  • Spin transfer torque

ASJC Scopus subject areas

  • Applied Mathematics
  • Computer Science Applications
  • Electrical and Electronic Engineering
  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

Cite this

Chen, T. Y., Ji, Y., Huang, S., Chien, C. L., & Stiles, M. D. (2009). Spin transfer torques by point-contact spin injection. In Proceedings of SPIE - The International Society for Optical Engineering (Vol. 7398). [73980C] https://doi.org/10.1117/12.825426

Spin transfer torques by point-contact spin injection. / Chen, T. Y.; Ji, Y.; Huang, Sunxiang; Chien, C. L.; Stiles, M. D.

Proceedings of SPIE - The International Society for Optical Engineering. Vol. 7398 2009. 73980C.

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Chen, TY, Ji, Y, Huang, S, Chien, CL & Stiles, MD 2009, Spin transfer torques by point-contact spin injection. in Proceedings of SPIE - The International Society for Optical Engineering. vol. 7398, 73980C, Spintronics II, San Diego, CA, United States, 8/2/09. https://doi.org/10.1117/12.825426
Chen TY, Ji Y, Huang S, Chien CL, Stiles MD. Spin transfer torques by point-contact spin injection. In Proceedings of SPIE - The International Society for Optical Engineering. Vol. 7398. 2009. 73980C https://doi.org/10.1117/12.825426
Chen, T. Y. ; Ji, Y. ; Huang, Sunxiang ; Chien, C. L. ; Stiles, M. D. / Spin transfer torques by point-contact spin injection. Proceedings of SPIE - The International Society for Optical Engineering. Vol. 7398 2009.
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