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Title: Beta (β) tungsten thin films: Structure, electron transport, and giant spin Hall effect

We use a simple magnetron sputtering process to fabricate beta (β) tungsten thin films, which are capable of generating giant spin Hall effect. As-deposited thin films are always in the metastable β-W phase from 3.0 to 26.7 nm. The β-W phase remains intact below a critical thickness of 22.1 nm even after magnetic thermal annealing at 280 °C, which is required to induce perpendicular magnetic anisotropy (PMA) in a layered structure of β-W/Co{sub 40}Fe{sub 40}B{sub 20}/MgO. Intensive annealing transforms the thicker films (>22.1 nm) into the stable α-W phase. We analyze the structure and grain size of both β- and α-W thin films. Electron transport in terms of resistivity and normal Hall effect is studied over a broad temperature range of 10 K to at least 300 K on all samples. Very low switching current densities are achieved in β-W/Co{sub 40}Fe{sub 40}B{sub 20}/MgO with PMA. These basic properties reveal useful behaviors in β-W thin films, making them technologically promising for spintronic magnetic random access memories and spin-logic devices.
Authors:
; ;  [1]
  1. Department of Physics, Brown University, Providence, Rhode Island 02912 (United States)
Publication Date:
OSTI Identifier:
22399004
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 106; 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:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ANISOTROPY; ANNEALING; COBALT COMPOUNDS; CURRENT DENSITY; ELECTRONS; GRAIN SIZE; HALL EFFECT; INTERFACES; IRON BORIDES; MAGNESIUM OXIDES; MAGNETRONS; RANDOMNESS; SPIN; SPUTTERING; THIN FILMS; TUNGSTEN