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arXiv · 2308.03220

A15 Phase Ta3Sb Thin Films: Direct Synthesis, Charge Transport and Spin-Orbit Torque

J. S. Jiang·Qianheng Du·Yi Li·Ulrich Welp·Ramakanta Chapai·Hanu Arava·Yuzi Liu·Yue Li·John Pearson·Ralu Divan·Anand Bhattacharya·Hyowon Park
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Abstract

Ta3Sb 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 Ta3Sb 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 Ta3Sb is estimated to be in the range of -526 to -1230 (hbar/e) S/cm at 300 K, lower in magnitude than the predicted value of -1400 (hbar/e) 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 non-ideal stoichiometry needed to stabilize the A15 structure.

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J. S. Jiang, Qianheng Du, Yi Li, Ulrich Welp, Ramakanta Chapai, Hanu Arava, Yuzi Liu, Yue Li, John Pearson, Ralu Divan, Anand Bhattacharya, Hyowon Park. 2023-08-06. A15 Phase Ta3Sb Thin Films: Direct Synthesis, Charge Transport and Spin-Orbit Torque. https://doi.org/10.1103/twfb-d5vd

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