Shape asymmetry enabled field free switching of perpendicular nanomagnets
Source abstract
Abstract
Spin Orbit Torque-Magnetic Random Access Memory (SOT-MRAM) is being developed as a successor to the Spin transfer torque MRAM (STT-MRAM) owing to its superior performance on the metrics of reliability and read-write speed. SOT switching of perpendicularly magnetized ferromagnet in the heavy metal/ferromagnet bilayer of SOT-MRAM unit cell requires an additional external magnetic field to support the spin-orbit torque generated by heavy metal to cause deterministic switching. This complexity can be overcome if an internal field can be generated to break the switching symmetry. We experimentally demonstrate that by engineering the shape of ferromagnet, an internal magnetic field capable of breaking the switching symmetry can be generated, which allows for deterministic switching by spin-orbit torques. We fabricated nanomagnets of Cobalt with triangular shape on top of Platinum and showed external magnetic field free switching between the two stable states of magnetization by application of nano-second voltage pulses. The experimental findings are consistent with the micro-magnetic simulation results of the proposed geometry.
Source: openaire · Quality: candidate unverified · Source record ↗
Research context
OpenAlex topics: Magnetic properties of thin films · Metamaterials and Metasurfaces Applications · Metallic Glasses and Amorphous Alloys
SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.
References (43)
Show source-provided references
1. Spin-transfer torque magnetoresistive random access memory technology status and future directions
2. Magnetoresistive random access memory: Present and future10.1109/TED.2020.2965403 ↗
3. Demonstrated reliability of 4-mb mram10.1109/TDMR.2004.837608 ↗
4. Status and outlook of mram memory technology
5. Spin–orbit torque switching of magnetic tunnel junctions for memory applications10.1016/j.jmmm.2022.169692 ↗
6. Spin-torque switching with the giant spin hall effect of tantalum10.1126/science.1218197 ↗
7. Current-induced switching of perpendicularly magnetized magnetic layers using spin torque from the spin hall effect10.1103/PhysRevLett.109.096602 ↗
8. A spin–orbit torque switching scheme with collinear magnetic easy axis and current configuration10.1038/nnano.2016.29 ↗
9. A perpendicular-anisotropy CoFeB–MgO magnetic tunnel junction10.1038/nmat2804 ↗
10. Field-free approaches for deterministic spin–orbit torque switching of the perpendicular magnet
11. Recent progress on controlling spin–orbit torques by materials design10.1038/s44306-024-00054-z ↗
12. Switching of perpendicular magnetization by spin–orbit torques in the absence of external magnetic fields10.1038/nnano.2014.94 ↗
13. Switching of perpendicularly polarized nanomagnets with spin orbit torque without an external magnetic field by engineering a tilted anisotropy10.1073/pnas.1507474112 ↗
14. Field-free switching of perpendicular magnetization induced by longitudinal spin–orbit-torque gradient10.1103/PhysRevApplied.17.024031 ↗
15. Chiral symmetry breaking for deterministic switching of perpendicular magnetization by spin–orbit torque10.1021/acs.nanolett.0c03972 ↗
16. Deterministic spin–orbit torque switching by a light-metal insertion10.1021/acs.nanolett.0c00647 ↗
17. Spin–orbit torque magnetization switching controlled by geometry10.1038/nnano.2015.252 ↗
18. Field-free spin–orbit-torque switching of perpendicular magnetization aided by uniaxial shape anisotropy10.1088/1361-6528/ab2831 ↗
19. First demonstration of field-free SOT-MRAM with 0.35 ns write speed and 70 thermal stability under 400 °C thermal tolerance by canted SOT structure and its advanced patterning/SOT channel technology
20. Field-free spin–orbit torque switching of perpendicular magnetic tunnel junction utilizing voltage-controlled magnetic anisotropy pulse width optimization
21. Symmetry-dependent field-free switching of perpendicular magnetization10.1038/s41565-020-00826-8 ↗
22. Current-induced self-switching of perpendicular magnetization in CoPt single layer10.1038/s41467-022-31167-w ↗
23. Field-free magnetization switching in CoPt induced by noncollinear antiferromagnetic Mn 3 Ga10.1103/PhysRevB.107.134422 ↗
24. Control of spin–orbit torques through crystal symmetry in WTe2/ferromagnet bilayers10.1038/nphys3933 ↗
25. Tilted spin current generated by the collinear antiferromagnet ruthenium dioxide10.1038/s41928-022-00744-8 ↗
26. Efficient perpendicular magnetization switching by a magnetic spin hall effect in a noncollinear antiferromagnet10.1038/s41467-022-32179-2 ↗
27. Cluster magnetic octupole induced out-of-plane spin polarization in antiperovskite antiferromagnet10.1038/s41467-021-26893-6 ↗
28. Magnetization switching by spin–orbit torque in an antiferromagnet–ferromagnet bilayer system10.1038/nmat4566 ↗
29. Efficient spin–orbit torque in magnetic trilayers using all three polarizations of a spin current10.1038/s41928-022-00735-9 ↗
30. Field-free switching of perpendicular magnetization through spin–orbit torque in antiferromagnet/ferromagnet/oxide structures10.1038/nnano.2016.109 ↗
31. Field-free magnetization reversal by spin-hall effect and exchange bias10.1038/ncomms10854 ↗
32. Switching a perpendicular ferromagnetic layer by competing spin currents10.1103/PhysRevLett.120.117703 ↗
33. Efficient spin-orbit-torque switching assisted by an effective perpendicular field in a magnetic trilayer10.1103/PhysRevApplied.16.014016 ↗
34. Spin currents and spin–orbit torques in ferromagnetic trilayers10.1038/s41563-018-0041-5 ↗
35. K. Garello, F. Yasin, H. Hody, S. Couet, L. Souriau, S.H. Sharifi, J. Swerts, R. Carpenter, S. Rao, W. Kim, et al., Manufacturable 300mm platform solution for field-free switching SOT-MRAM, in: 2019 Symposium on VLSI Circuits (2019) T194-T195, http://dx.doi.org/10.23919/VLSIC.2019.8778100.10.23919/VLSIT.2019.8776537 ↗
36. Observation of field-free spin–orbit torque switching in a single crystalline (Ga, Mn)(As, P) ferromagnetic film with perpendicular anisotropy10.1063/5.0226588 ↗
37. Perpendicular switching of a single ferromagnetic layer induced by in-plane current injection10.1038/nature10309 ↗
38. Tilting of the spin orientation induced by rashba effect in ferromagnetic metal layer10.1063/1.3502596 ↗
39. Layer thickness dependence of the current-induced effective field vector in ta10.1038/nmat3522 ↗
40. Enhancement of perpendicular magnetic anisotropy and transmission of spin-hall-effect-induced spin currents by a hf spacer layer in w/Hf/Cofeb/mgo layer structures10.1063/1.4866965 ↗
41. Interfacial and bulk spin hall contributions to fieldlike spin–orbit torque generated by iridium10.1103/PhysRevB.103.184416 ↗
42. A. Chouhan, A. Erram, A.A. Tulapurkar, Out-of-plane angle resolved second harmonic hall analysis in perpendicular magnetic anisotropy systems. arXiv.2508.17429.
43. The design and verification of Mumax310.1063/1.4899186 ↗