Anomalous temperature dependence of current-induced torques in CoFeB/MgO heterostructures with Ta-based underlayers

Junyeon Kim, Jaivardhan Sinha, Seiji Mitani, Masamitsu Hayashi, Saburo Takahashi, Sadamichi Maekawa, Michihiko Yamanouchi, Hideo Ohno

Research output: Contribution to journalArticlepeer-review

79 Citations (Scopus)

Abstract

We have studied the underlayer thickness and temperature dependencies of the current-induced effective field in CoFeB/MgO heterostructures with Ta-based underlayers. The underlayer thickness at which the effective field saturates is found to be different between the two orthogonal components of the effective field; i.e., the dampinglike term tends to saturate at a smaller underlayer thickness than the fieldlike term. For large underlayer thickness films in which the effective field saturates, we find that the measurement temperature significantly influences the size of the effective field. A striking difference is found in the temperature dependence of the two components: the dampinglike term decreases whereas the fieldlike term increases with increasing temperature. Using a simple spin diffusion-spin transfer model, we find that all of these results can be accounted for provided the real and imaginary parts of an effective spin mixing conductance are negative. These results imply that either spin transport in this system is different from conventional metallic interfaces or effects other than spin diffusion into the magnetic layer need to be taken into account in order to model the system accurately.

Original languageEnglish
Article number174424
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume89
Issue number17
DOIs
Publication statusPublished - 2014 May 23

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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