text: Beta-tungsten (β-W) is a metastable phase of tungsten widely observed in tungsten thin films. While the commonly existing stable alpha-tungsten (α-W) has a body-centered cubic (A2) structure, β-W adopts the topologically close-packed A15 structure containing eight atoms per unit cell, and it irreversibly transforms to the stable α phase through thermal annealing of up to 650 °C. It has been found that β-W possesses the giant spin Hall effect, wherein the applied charge current generates a transverse spin current, and this leads to potential applications in magnetoresistive random access memory devices.