Deterministic switching of a perpendicularly polarized magnet using unconventional spin-orbit torques in WTe2.

Spin-orbit torque (SOT)-driven deterministic control of the magnetic state of a ferromagnet with perpendicular magnetic anisotropy is key to next-generation spintronic applications including non-volatile, ultrafast and energy-efficient data-storage devices. However, field-free deterministic switching of perpendicular magnetization remains a challenge because it requires an out-of-plane antidamping torque, which is not allowed in conventional spin-source materials such as heavy metals and topological insulators due to the system's symmetry. The exploitation of low-crystal symmetries in emergent quantum materials offers a unique approach to achieve SOTs with unconventional forms. Here we report an experimental realization of field-free deterministic magnetic switching of a perpendicularly polarized van der Waals magnet employing an out-of-plane antidamping SOT generated in layered WTe2, a quantum material with a low-symmetry crystal structure. Our numerical simulations suggest that the out-of-plane antidamping torque in WTe2 is essential to explain the observed magnetization switching.

Visual Acuity Outcomes and Loss to Follow-up in the Treatment of Amblyopia in Children From Lower Socioeconomic Backgrounds.

PURPOSE: To compare visual acuity outcomes and loss to follow-up after initiation of treatment for unilateral amblyopia in children from different socioeconomic backgrounds. METHODS: Medical records of children diagnosed as having unilateral amblyopia at an initial encounter between 2015 and 2018 were reviewed. Medicaid and private insurance were used as proxies for socioeconomic status (SES). Data points were collected at the patients' initial, follow-up, and final visits. Visual acuity improvement was the primary outcome variable in patients with at least one follow-up appointment. In a separate analysis, failure to attend a single follow-up appointment was examined for associations with SES, race, sex, and distance traveled to appointments. RESULTS: Seventy-three patients met the inclusion criteria; of these, 28 had Medicaid and 45 had private insurance. Visual acuity improved by 2.86 lines in the Medicaid group and 2.98 lines in the private insurance group (P = .84). Number of missed appointments and distance traveled did not correlate with visual acuity improvement. In the loss to follow-up subanalysis, 40 of 141 (28.4%) patients with Medicaid and 11 of 107 (10.3%) patients with private insurance failed to attend a single follow-up visit (P = .001). No association was found between loss to follow-up and race, sex, or distance traveled. CONCLUSIONS: Visual acuity outcomes of treatment for amblyopia did not differ between patients with Medicaid and patients with private insurance who followed up. However, patients with Medicaid were much more likely to be immediately lost to follow-up. Measures should be taken by eye care providers and pediatricians to increase follow-up in patients from low SES populations. [J Pediatr Ophthalmol Strabismus. 2022;59(2):110-117.].