Deterministic Spin-Orbit Torque Switching in 2D Dilute Magnetic Semiconductors Above Room Temperature

Two-dimensional (2D) van der Waals (vdW) magnets with perpendicular magnetic anisotropy (PMA) hold great potential for next-generation high-density, energy-efficient spintronics^1–9. Recent breakthroughs have emerged with the discovery of Fe₃GaTe₂ ,PtTe₂ and CrTe₂, boasting Tc exceeding 300K, opening possibilities for constructing functional 2D magnetic devices operating at room temperature^10–14. However, achieving high-efficiency spin-orbit torque (SOT) switching of monolayer vdW magnets at room temperature poses a significant challenge, particularly in the absence of an external magnetic field. Here we demonstrate an ultra-low power, field-free, deterministic, and nonvolatile PMA switching of SOT system up to 370 K using a dilute magnetic semiconductor (DMS), monolayer Fe:MoS₂¹⁵, through interfacial spin-orbit coupling with a Pt Hall bar. A clear anomalous Hall effect (AHE) loop shift is observed at a zero in-plane magnetic field, verifying the existence of z spins in the Fe:MoS₂/Pt heterostructure, which induces a damping-like torque that facilitates field-free SOT switching with the current density of 10⁵ A cm⁻² at 370K. The Fe doping into MoS₂ disintegrates the rotational crystal symmetry, evidenced by the crystal axis dependency of the switching in Fe:MoS₂/Pt heterostructures with PMA. A strong topological Hall effect (THE) was also observed, attributed to interfacial Dzyaloshinskii-Moriya interaction (DMI). This field-free SOT application using a 2D monolayer dilute magnetic semiconductor provides a new pathway for developing highly power-efficient spintronic devices.<br/><br/>References:<br/>1. Ou, Y. <i>et al.</i> ZrTe2/CrTe2: an epitaxial van der Waals platform for spintronics. <i>Nat. Commun.</i> <b>13</b>, 2972 (2022).<br/>2. Gong, C. <i>et al.</i> Discovery of intrinsic ferromagnetism in two-dimensional van der Waals crystals. <i>Nature</i> <b>546</b>, 265–269 (2017).<br/>3. Verzhbitskiy, I. A. <i>et al.</i> Controlling the magnetic anisotropy in Cr2Ge2Te6 by electrostatic gating. <i>Nat. Electron.</i> <b>3</b>, 460–465 (2020).<br/>4. Lohmann, M. <i>et al.</i> Probing Magnetism in Insulating Cr ₂ Ge ₂ Te ₆ by Induced Anomalous Hall Effect in Pt. <i>Nano Lett.</i> <b>19</b>, 2397–2403 (2019).<br/>5. Huang, B. <i>et al.</i> Layer-dependent ferromagnetism in a van der Waals crystal down to the monolayer limit. <i>Nature</i> <b>546</b>, 270 (2017).<br/>6. Klein, D. R. <i>et al.</i> Probing magnetism in 2D van der Waals crystalline insulators via electron tunneling. <i>Science</i> <b>360</b>, 1218–1222 (2018).<br/>7. Song, T. <i>et al.</i> Giant tunneling magnetoresistance in spin-filter van der Waals heterostructures. <i>Science</i> <b>360</b>, 1214–1218 (2018).<br/>8. Chen, W. <i>et al.</i> Direct observation of van der Waals stacking–dependent interlayer magnetism. <i>Science</i> <b>366</b>, 983–987 (2019).<br/>9. Thiel, L. <i>et al.</i> Probing magnetism in 2D materials at the nanoscale with single-spin microscopy. <i>Science</i> <b>364</b>, 973–976 (2019).<br/>10. Kajale, S. N., Nguyen, T., Hung, N. T., Li, M. & Sarkar, D. Field-free deterministic switching of all–van der Waals spin-orbit torque system above room temperature. <i>Sci. Adv.</i> <b>10</b>, eadk8669 (2024).<br/>11. Wang, F. <i>et al.</i> Field-free switching of perpendicular magnetization by two-dimensional PtTe2/WTe2 van der Waals heterostructures with high spin Hall conductivity. <i>Nat. Mater.</i> (2024) doi:10.1038/s41563-023-01774-z.<br/>12. Liu, X. <i>et al.</i> Wafer-Scale Epitaxial Growth of the Thickness-Controllable Van Der Waals Ferromagnet CrTe2 for Reliable Magnetic Memory Applications. <i>Adv. Funct. Mater.</i> <b>33</b>, 2304454 (2023).<br/>13. Li, W. <i>et al.</i> Room-Temperature van der Waals Ferromagnet Switching by Spin-Orbit Torques. <i>Adv. Mater.</i> <b>35</b>, 2303688 (2023).<br/>14. Zhang, X. <i>et al.</i> Room-temperature intrinsic ferromagnetism in epitaxial CrTe2 ultrathin films. <i>Nat. Commun.</i> <b>12</b>, 2492 (2021).<br/>15. Fu, S. <i>et al.</i> Enabling room temperature ferromagnetism in monolayer MoS2 via in situ iron-doping. <i>Nat. Commun.</i> <b>11</b>, 2034–2034 (2020).