Yihua Bai

Time-resolved and energy-dispersed spin excitation in ferromagnets and clusters under influence of femtosecond laser pulses

When an ultrafast laser impinges a magnetic material, it excites charge and then, via spin-orbit-coupling, spin. This holds great promise for the future magnetic storage. However, the coupling of the two dynamics is far from clear, which hampers the experimental effort in femtosecond magnetism. Since not every excitation induces the same spin excitation, a clear understanding of the correlation between charge and spin is crucial. In this paper we investigate in a complete first-principles manner the energy dispersion of the spin-moment change in ferromagnetic Ni and the effect of the distance between the magnetic centers upon the spin localization and local-spin-flip times in metallic chains. Thus we establish the missing link between the spin-momentum change and the density-of-states change, and derive rules-of-thumb for localized spin manipulation.

Understanding laser-induced ultrafast magnetization in ferromagnets: First-principles investigation

Ultrafast demagnetization in ferromagnets has attracted much attention both experimentally and theoretically for over a decade. This includes a lively debate as to whether the observed signal represents a true magnetization process. Here, a first-principles and time-dependent calculation is performed for ferromagnetic nickel under laser illumination to directly compute the magnetization and polarization changes. It is found that while the polarization exhibits both rapid and slow oscillations, the magnetization mainly shows a slow oscillation. The slow component of the polarization generally follows the magnetization evolution with a margin of 2–3fs deviation. The correlation between the magnetization and polarization tends to be better in the absence of laser radiation.

A new and simple model for magneto-optics uncovers an unexpected spin switching

In magneto-optics the spin angular momentum

Ultrafast reduction of exchange splitting in ferromagnetic nickel

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Manipulating femtosecond magnetization in ferromagnets and molecular magnets through laser chirp

of a sample is indirectly probed by the rotation angle and ellipticity, which are mainly determined by the off-diagonal susceptibility

Switching ferromagnetic spins by an ultrafast laser pulse: Emergence of giant optical spin-orbit torque

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Magnetic spin moment reduction in photoexcited ferromagnets through exchange interaction quenching: beyond the rigid band approximation

. A direct and analytic relation between

First-principles and model simulation of all-optical spin reversal

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Is perpendicular magnetic anisotropy essential to all-optical ultrafast spin reversal in ferromagnets?

and

Imaging superatomic molecular orbitals in a C60 molecule through four 800-nm photons

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