Role of critical spin fluctuations in ultrafast demagnetization of transition-metal rare-earth alloys

Abstract

Ultrafast magnetization dynamics induced by femtosecond laser pulses have been measured in ferrimagnetic Co0.8Gd0.2, Co.74Tb.26 and Co.86Tb.14 alloys. Using element sensitivity of X-ray magnetic circular dichroism at the Co L3, Tb M5 and Gd M5 edges we evidence that the demagnetization dynamics is element dependent. We show that a thermalization time as fast as 280 fs is observed for the rare-earth in the alloy, when the laser excited state temperature is below the compensation temperature. It is limited to 500 fs when the laser excited state temperature is below the Curie temperature (Tc). We propose critical spin fluctuations in the vicinity of TC as the mechanism which reduces the demagnetization rates of the 4f electrons in transition-metal rare-earth alloys whereas at any different temperature the limited demagnetization rates could be avoided.

11 pages, 4 figures

Cited by in corpus (20)

• Very large domain wall velocities in Pt/Co/Gd trilayers with Dzyaloshinskii-Moriya interaction
• Femtosecond X-ray magnetic circular dichroism absorption spectroscopy at an X-ray free electron laser
• Multiscale modeling of ultrafast element-specific magnetization dynamics of ferromagnetic alloys
• Controlling the Polarity of the Transient Ferromagnetic-Like State in Ferrimagnets
• Exchange relaxation as the mechanism of ultrafast spin reorientation in two-sublattice ferrimagnets
• Magnetic and all-optical switching properties of amorphous Tb${}_x$Co${}_{100-x}$ alloys
• Ultrafast demagnetization of Pt magnetic moment in L1${}_0$-FePt probed by hard x-ray free electron laser
• Nanoscale transient magnetization gratings excited and probed by femtosecond extreme ultraviolet pulses
• Element-selective tracking ultrafast demagnetization process in Co/Pt multilayer thin films by the resonant magneto-optical Kerr effect
• Thermal rectification and heat amplification in a nonequilibrium V-type three-level system
• Laser-induced ultrafast demagnetization and perpendicular magnetic anisotropy reduction in a Co${}_{88}$Tb${}_{12}$ thin film with stripe domains
• Irreversible transformation of ferromagnetic ordered stripe domains in single-shot IR pump - resonant X-ray scattering probe experiments
• Ultrafast demagnetization in ferromagnetic materials: Origins and progress
• Element-resolved ultrafast demagnetization rates in ferrimagnetic CoDy
• Plasmon-enhanced optical control of magnetism at the nanoscale via the inverse Faraday effect
• Ultrafast hot-electron induced quenching of Tb4f magnetic order
• Laser-induced Demagnetization in van der Waals $XY$- and Ising-like Antiferromagnets NiPS${}_3$ and FePS${}_3$
• Study of the ultrafast dynamics of ferromagnetic materials with a Quantum Monte Carlo atomistic model
• Laser induced ultrafast Gd 4f spin dynamics in Co100-xGdx alloys by means of time-resolved XMCD
• Time-Resolved XUV absorption spectroscopy and magnetic circular dichroism at the Ni $M_{2,3}$-edges