Abstract
Scanning tunneling microscopy experiments using iron-coated tungsten tips and current-carrying tungsten films have been conducted. An asymmetry of the tunneling current with respect to the change of the direction of the bias current through a tungsten film has been observed. It is argued that this asymmetry is a manifestation of the spin Hall effect in the current-carrying tungsten film. Nanoscale variations of this asymmetry across the tungsten film have been studied by using the scanning tunneling microscopy technique.
Highlights
The experimental study of the spin Hall effect (SHE) in conducting films is currently a very active area of research
Previously,[8,9] this technique was used in the study of the SHE in beta-phase tungsten films by using tungsten tips, and an appreciable asymmetry in the tunneling currents with respect to the change in the polarity of the tunneling voltage was observed
It was observed that in this case there exists another asymmetry in tunneling currents with respect to the change in the direction of the bias current
Summary
The experimental study of the spin Hall effect (SHE) in conducting films is currently a very active area of research This is due to the appeal of the SHE as a unique physical phenomenon[1,2,3] as well as to its many promising applications.[4,5,6,7] In this paper, a scanning tunneling microscopy (STM) based technique for local sensing of the SHE is discussed. In the case of tungsten tips, no tunneling current asymmetry with respect to the change in the direction of the bias current through the tungsten films was found. By using the STM technique, nanoscale variations of the above asymmetry across the tungsten film were studied These variations may be caused by the nanoscale granular structure of the tungsten film which results in highly non-uniform bias current density distributions.
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