${\mathrm{Ta}}_3\mathrm{Sb}$ is one of the A15 compounds that have been predicted to have giant spin Hall conductivities due to the gapped Dirac-like band crossings in their electronic structures. We use co-sputtering to directly synthesize thin films of ${\mathrm{Ta}}_3\mathrm{Sb}$ and identify a large window of Ta:Sb flux ratio that permits the formation of single-phase A15 structure. These sputtered films have an actual Ta:Sb atomic ratio of 4:1, as determined from Rutherford backscattering spectrometry. Their high resistivity, at the Mott-Ioffe-Regel limit, suggests that the electron mean free path is comparable to interatomic distances. From harmonic Hall and spin-torque ferromagnetic resonance measurements, the intrinsic spin Hall conductivity of thin film ${\mathrm{Ta}}_3\mathrm{Sb}$ is estimated to be in the range of $-526$ to $-1230\left(\hslash /e\right)\text{S/cm}$ at 300 K, lower in magnitude than the predicted value of $-1400\left(\hslash /e\right)\text{S/cm}$. First-principles calculations of the electronic structure show that the discrepancy is consistent with an increase of the Fermi level due to the nonideal stoichiometry needed to stabilize the A15 structure.

Close

PrevNext

View figure in article

• Spin Hall effect
• Spin-orbit torque
• Topological materials
• Thin films
• Density functional theory
• Hall bar
• Physical vapor deposition