Optical Constants of Eight Rare Earth Elements

Ward, L.

doi:10.1016/b978-012544415-6.50105-9

Cited by 1 publication

(2 citation statements)

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“…Complementary information on the dynamics in the bulk is obtained from the transient linear reflectivity. Linear reflection of photons occurs within the optical penetration depth of Gd of about 20 nm [169] 2 and thus averages over the whole film with a sensitivity that is exponentially damped with increasing distance from the surface. The pump-induced variation is determined from the reflected intensity I ν measured with a photodiode by…”

Section: Time-resolved Linear and Nonlinear Optical Spectroscopymentioning

confidence: 99%

“…The e-ph coupling is modelled with an energy-transfer rate H (T e , T l ) that was derived by Kaganov et al [87] by summation of all one-phonon emission and absorption processes assuming thermal electron and phonon distributions. The temperature dependence of C l is described using the Debye approximation with a high temperature value of [75], the optical penetration depth of 40 nm [169] (also see footnote 2), and the Debye temperature of 163 K [161], the measured transient electron temperature is reproduced (figure 10(a)). Following Hohlfeld et al, ballistic electron transport is included through an effective increase of the penetration depth by 20 nm [79].…”

Section: Relaxation Dynamics Of Hot Electron Distributionsmentioning

confidence: 99%

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Coherent and incoherent excitations of the Gd(0001) surface on ultrafast timescales

Bovensiepen

2007

J. Phys.: Condens. Matter

115

112

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The dynamics of collective excitations of electrons, phonons, and spins are of fundamental interest to develop a microscopic understanding of interactions among elementary excitations and of the respective relaxation mechanisms. The present work employs pump-probe investigations on the femto-and picosecond timescale to study the ultrafast dynamics of electrons, spin-waves, and phonons after intense optical excitation. The Gd(0001) surface, which serves as a model system for a ferromagnetic metal, is investigated by complementary timeresolved techniques, photoelectron spectroscopy and linear/nonlinear optical spectroscopy. The energy relaxation of hot electrons is analysed by transient changes of the electron distribution function and of the complex self-energy of the occupied component of the 5d z 2 surface state. In combination with a simplified description by the two-temperature model this analysis characterizes the optically excited state quantitatively. We analyse the mechanism that leads to a drop in spin polarization upon optical excitation, which is observed in nonlinear magneto-optics. Since the exchange splitting, analysed by photoemission, is not affected under these non-equilibrium conditions, we propose spin-flip scattering of hot electrons to be responsible. The Gd(0001) surface presents a previously unknown coupled phonon-magnon mode, which can be excited by femtosecond laser pulses. Time-resolved detection of the optical second harmonic yield separates spin dynamics from electron and lattice contributions. A coherent phonon-magnon mode at 3 THz, which is driven by electronic excitations of surface and bulk states, is observed. Time-resolved photoemission provides information on the interaction mechanism. We find that the binding energy of the surface state oscillates at the same frequency. In combination with calculations of the surface state binding energy upon lattice contraction this suggests a phonon-magnon coupling due to spin-flip scattering, in contrast to the conventional type mediated by spin-orbit interaction.

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Section: Time-resolved Linear and Nonlinear Optical Spectroscopymentioning

confidence: 99%