All-optical switching in granular ferromagnets caused by magnetic circular dichroism

Abstract

Magnetic recording using circularly polarized femto-second laser pulses is an emerging technology that would allow write speeds much faster than existing field driven methods. However, the mechanism that drives the magnetization switching in ferromagnets is unclear. Recent theories suggest that the interaction of the light with the magnetized media induces an opto-magnetic field within the media, known as the inverse Faraday effect. Here we show that an alternative mechanism, driven by thermal excitation over the anisotropy energy barrier and a difference in the energy absorption depending on polarization, can create a net magnetization over a series of laser pulses in an ensemble of single domain grains. Only a small difference in the absorption is required to reach magnetization levels observed experimentally and the model does not preclude the role of the inverse Faraday effect but removes the necessity that the opto-magnetic field is 10s of Tesla in strength.

18 pages, 5 figures

References in corpus (2)

• All-optical control of ferromagnetic thin films and nanostructures
• Switching times of nanoscale FePt: finite size effects on linear reversal mechanism

Cited by in corpus (16)

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• Magnetic switching in granular FePt layers promoted by near-field laser enhancement
• Ultrafast coherent all-optical switching of an antiferromagnet with the inverse Faraday effect
• Plasmon-induced demagnetization and magnetic switching in nickel nanoparticle arrays
• Interface-induced field-like optical spin torque in a ferromagnet/heavy metal heterostructure
• Realistic micromagnetic description of all-optical ultrafast switching processes in ferrimagnetic alloys
• Heat accumulation and all-optical switching by domain wall motion in Co/Pd superlattices
• Heat diffusion in magnetic superlattices on glass substrates
• Magnetization reversal of a ferromagnetic Pt/Co/Pt film by helicity dependent absorption of visible to near-infrared laser pulses
• Role of longitudinal fluctuations in L$1_0$ FePt
• Laser-induced helicity and texture-dependent switching of nanoscale stochastic domains in a ferromagnetic film
• Demagnetizing fields in all-optical switching
• Exploring the impact of the inverse Faraday effect on all-optical helicity-dependent magnetization switching
• A Femtosecond Magnetic Circular Dichroism Spectrometer