US 12,469,519 B2
Magnetic media
Kilian James Darrie Stenning, London (GB); Xiaofei Xiao, London (GB); Holly Holder, London (GB); Jack Carter Gartside, London (GB); Rupert Francis Maximillian Oulton, London (GB); and William Richard Branford, London (GB)
Assigned to Imperial College Innovations Limited, London (GB)
Appl. No. 18/714,732
Filed by Imperial College Innovations Limited, London (GB)
PCT Filed Nov. 30, 2022, PCT No. PCT/GB2022/053032
§ 371(c)(1), (2) Date May 30, 2024,
PCT Pub. No. WO2023/099887, PCT Pub. Date Jun. 8, 2023.
Claims priority of application No. 2117279 (GB), filed on Nov. 30, 2021.
Prior Publication US 2025/0029633 A1, Jan. 23, 2025
Int. Cl. G11B 11/105 (2006.01)
CPC G11B 11/10506 (2013.01) [G11B 11/10582 (2013.01); G11B 2220/2516 (2013.01)] 18 Claims
OG exemplary drawing
 
1. A magnetic medium comprising:
a thin film magnet structure formed of a ferromagnetic alloy or compound; and
one or more optical structures, each optical structure comprising a dielectric layer having an upper surface and a lower surface, the dielectric layer interposed between the thin film magnet structure and a substrate having a reflective portion with the lower surface facing the reflective portion;
wherein the thin film magnet structure comprises one or more ferromagnetic domains and is coupled to the one or more optical structures, each of the one or more ferromagnetic domains having a magnetization that is switchable between two or more states;
wherein each of the one or more optical structures is configured to increase absorbance of light at a target wavelength in the thin film magnet structure, said configuration comprising that the corresponding dielectric layer is substantially transparent at a target wavelength, and has a thickness such that light at the target wavelength reflected from the lower surface interferes destructively with incident light at the target wavelength and light at the target wavelength reflected from the upper surface back towards the lower surface, such that in response to illumination of a ferromagnetic domain with continuous-wave light including the target wavelength, that ferromagnetic domain undergoes all-optical magnetic switching.