Large and robust charge-to-spin conversion in sputtered conductive WTe with disorder

Efficient Spin-Orbit Torque Generation in Semiconducting WTe2 with Hopping Transport

“…Current-induced magnetization switching at a low critical switching current density of J c ≈ 7.05 × 10 9 A/m 2 further confirms the sizable DL-SOT efficiency. By studying the co-sputtered W 100– x Te x samples, we find that ξ DL W 100 – x Te x is strongly composition dependent in terms of both magnitude and sign, which can explain the huge discrepancies of the observed ξ DL in several recent reports. , Additionally, the distinct difference between the layer thickness dependence of ξ DL WTe 2 and ξ DL W 100 – x Te x suggests that both bulk and interfacial origins of SOTs are possible to be generated by sputter-deposited chalcogenides. These unconventional features together with its low α and sizable ξ DL make the amorphous WTe 2 -based heterostructure an intriguing system for novel SOT applications.…”

“…As shown in Figure a, the switching polarities depend on the applied H x , which is consistent with the SOT-driven switching mechanism. , More importantly, the critical switching current density, J c , of the WTe 2 /CoTb structure is further demonstrated to be J c ≈ 7.05 × 10 9 A/m 2 , which is much lower than those from the 5d transition metal-based heterostructures ( J c ≈ 10 11 A/m 2 ) ,, and comparable to the TI cases. − Note that this value is of the same order as the exfoliated 80 nm-thick WTe 2 case reported by Shi. S et al ( J c ≈ 3 × 10 9 A/m 2 ) and smaller than the sputtered WTe x case reported by Li et al ( J c ≈ 1.5 × 10 10 A/m 2 ) . In addition to J c , the SOC layer thickness also needs to be taken into account to estimate the overall switching performance.…”

Disorder is not always bad for charge-to-spin conversion in WTe2

“…Disorder is not always bad for charge-to-spin conversion in WTe 2 Marcos H.D. Guimara ˜es 1, * and Saroj P. Dash 2 The Wang group at Stanford University demonstrates disordered WTe x films for efficient charge-to-spin conversion phenomena. The deposition of these films by sputtering and the charge-to-spin conversion resilience against disorder make them attractive for applications in new magnetic memory devices.…”

“…In this issue of Matter, 2 Li et al demonstrate that disordered WTe x films deposited by sputtering still maintain several of the appealing properties of its crystalline and stoichiometric cousin, WTe 2 . Their films show similar behavior of conductivity as a function of temperature as well as weak antilocalization, indicating that their disordered and non-stoichiometric films still possess the signatures of a semimetal with high spin-orbit coupling.…”

“…Inset: Cross-section scanning transmission electron microscopy image of WTe x /CoFeB bilayer capped by MgO. Adapted from Li et al2…”