Unravelling oxygen driven ? to ? phase transformation in tungsten.

ABSTRACT: Thin films of ?-W are the most interesting for manipulating magnetic moments using spin-orbit torques, and a clear understanding of ? to ? phase transition in W by doping impurity, especially oxygen, is needed. Here we present a combined experimental and theoretical study using grazing incidence X-ray diffraction, photoelectron spectroscopy, electron microscopy, and ab initio calculations to explore atomic structure, bonding, and oxygen content for understanding the formation of ?-W. It is found that the W films on SiO₂/Si have 13-22 at.% oxygen in A15 ? structure. Ab initio calculations show higher solution energy of oxygen in ?-W, and a tendency to transform locally from ? to ? phase with increasing oxygen concentration. X-ray absorption spectroscopy also revealed local geometry of oxygen in ?-W, in agreement with the simulated one. These results offer an opportunity for a fundamental understanding of the structural transition in ?-W and further development of ?-W phase for device applications.

SUBMITTER: Chattaraj A 

PROVIDER: S-EPMC7477580 | biostudies-literature | 2020 Sep

REPOSITORIES: biostudies-literature