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Title: Abnormal bias dependence of magnetoresistance in CoFeB/MgO/Si spin-injection tunnel contacts

We report a strong bias voltage dependence of magnetoresistance (MR) in CoFeB/MgO/Si spin-injection tunnel contacts using the three-terminal Hanle geometry. When a bias voltage is relatively large, the MR is composed of two characteristic signals: a conventional Hanle signal observed at a low magnetic field, which is due to the precession of injected spins, and another signal originating from the rotation of the magnetization at a larger magnetic field. In contrast, for a small bias voltage, additional signals appear at a wide range of magnetic fields, which occasionally overwhelms the conventional Hanle signals. Because the additional signals are pronounced at a low bias and are significantly reduced by annealing at moderate temperatures, they can be attributed to multi-step tunneling via defect states at the interfaces or tunnel barrier. Our results demonstrate that the spin injection signal caused by the defect states can be evaluated by its bias voltage dependence.
Authors:
;  [1] ;  [1] ;  [2] ; ;  [3]
  1. Department of Materials Science and Engineering, KAIST, Daejeon 305-701 (Korea, Republic of)
  2. (Korea, Republic of)
  3. Spin Engineering Physics Team, Division of Scientific Instrument, KBSI, Daejeon 305-806 (Korea, Republic of)
Publication Date:
OSTI Identifier:
22486001
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 107; Journal Issue: 18; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ANNEALING; ELECTRIC POTENTIAL; GEOMETRY; INTERFACES; MAGNESIUM OXIDES; MAGNETIC FIELDS; MAGNETIZATION; MAGNETORESISTANCE; PRECESSION; ROTATION; SIGNALS; SPIN; TUNNEL EFFECT