<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi mathvariant="italic">GW</mml:mi><mml:mo>+</mml:mo><mml:mi>T</mml:mi></mml:mrow></mml:math>theory of excited electron lifetimes in metals

Zhukov, V. P.; Chulkov, Eugene V.; Echenique, Pedro M.

doi:10.1103/physrevb.72.155109

Cited by 80 publications

(86 citation statements)

References 60 publications

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“…The mechanism we propose for enhancement of the magnetization is based on filling of majority spin states above the Fermi energy in the Fe layer by majority spins coming from Ni. This leads to a transient magnetization increase in the Fe layer, above its maximum value defined by the Curie curve at T = 0 K. The increase in the magnetic signal from the Fe layer is a result of a strong asymmetry in the spin-dependent hot-electron lifetimes in magnetic materials and, hence, the transport properties of the hot majority and minority spin carriers [27][28][29] within the Ni and Fe layers. Excited minority spin electrons originating in the optical excitation in both the Al and Ni layers have much shorter lifetimes when passing via superdiffusion through the Ni layer, and are therefore stopped before they can reach the Fe layer.…”

Section: Resultsmentioning

confidence: 99%

“…The z coordinate is defined as being normal to the layers. The spin-and excitation energy-dependent electronic lifetimes and velocities 27,29 , as well as the ratio of excited majority to minority spin electrons 35 , are taken from ab initio calculations. The femtosecond spin dynamics follows from m(E, z, t) = 2µ B [n(↑, E, z, t) − n(↓, E, z, t)], with m(E, z, t) the transient spin moment of excited electrons along the depth profile.…”

Section: Methodsmentioning

confidence: 99%

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Ultrafast magnetization enhancement in metallic multilayers driven by superdiffusive spin current

et al. 2012

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Ultrafast magnetization enhancement in metallic multilayers driven by superdiffusive spin current

et al. 2012

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“…Empirically, it is well known that the response function in the T -matrix approximation leads to reasonable results for the magnetic response function [43,44].¯ T has been used in various studies to account for magnetic fluctuations in non-SC systems [46][47][48][49].…”

Section: A Inclusion Of the Relevant Diagramsmentioning

confidence: 99%

Superconducting pairing mediated by spin fluctuations from first principles

et al. 2014

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We present the derivation of an ab initio and parameter-free effective electron-electron interaction that goes beyond the screened random phase approximation and accounts for superconducting pairing driven by spin fluctuations. The construction is based on many-body perturbation theory and relies on the approximation of the exchange-correlation part of the electronic self-energy within time-dependent density functional theory. This effective interaction is included in an exchange-correlation kernel for superconducting density functional theory in order to achieve a completely parameter free superconducting gap equation. First results from applying the new functional to a simplified two-band electron gas model are consistent with experiments.

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“…Unfortunately, Ref. [15] does not provide inelastic lifetimes for excited electrons with low energies (i.e., from the Fermi level to 0.5 eV above). We made a linear extrapolation to estimate lifetimes for the lowest energies; the influence of this approximation is discussed further below, together with those of other approximations.…”

mentioning

confidence: 99%

“…[2], the ratio of excited spin-up to spin-down electrons from [14], and the spin-dependent inelastic lifetimes and velocities from Ref. [15]. Unfortunately, Ref.…”

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confidence: 99%

Superdiffusive Spin Transport as a Mechanism of Ultrafast Demagnetization

Battiato

Carva²,

Oppeneer³

2010

Phys. Rev. Lett.

743

698

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We propose a semi-classical model for femtosecond-laser induced demagnetization due to spinpolarized excited electron diffusion in the super-diffusive regime. Our approach treats the finite elapsed time and transport in space between multiple electronic collisions exactly, as well as the presence of several metal films in the sample. Solving the derived transport equation numerically we show that this mechanism accounts for the experimentally observed demagnetization within 200 fs in Ni, without the need to invoke any angular momentum dissipation channel.Excitation with femtosecond laser pulses is known for more than a decade to cause an ultrafast quenching of the magnetization in metallic ferromagnets [1]. The achieved demagnetization times are typically 100-300 fs for ferromagnets such as Ni [1,2]. Hence, laser-induced demagnetization opens up new, interesting routes for magnetic recording with hitherto unprecedented speeds [3]. However, in spite of the technological importance the mechanism underlying the femtosecond demagnetization remains highly controversial. A common belief is that there should exist an ultrafast channel for the dissipation of spin angular momentum [4][5][6][7][8]. Several such mechanisms through which an excited electron can undergo a spinflip in a ferromagnetic metal are currently being debated. The main proposed mechanisms for a fast spin-flip process are a Stoner excitation, an inelastic magnon scattering, an Elliott-Yafet-type of phonon scattering [4,5], spin-flip Coulomb scattering [6], laser-induced spin-flips [7], or relativistic quantum electrodynamic processes [8]. An effect that, until recently [9], has been regarded to play only a marginal role is the spin-polarized transport of laser-excited hot electrons.In this Letter we show that spin-dependent transport of laser-excited electrons provides a considerable contribution to the ultrafast demagnetization process and can even completely explain it. We demonstrate this by developing a transport equation for the super-diffusive flow of spin-polarized electrons. A few approaches to describe the electron motion have been attempted previously [10,11]. In our theory, however, we take into account the whole process of multiple, spin-conserving electron scattering events and electron cascades created by inelastic electron scattering. Also the presence of different metallic films in the probed material is treated. We solve the developed theory numerically for ferromagnetic Ni, for which the femtosecond demagnetization is well documented [1,2,12], and show that a large demagnetization in a few hundred femtoseconds is generated.The typical geometry for a femtosecond laser experiment is depicted in Fig. 1. The intense laser beam creates excited hot electrons in the ferromagnetic film, which will start to move in a random direction. Our goal is to compute the time-dependent magnetization resulting from the super-diffusive motion in the laser spot. Due to the fact that the electronic mean-free-path (up to a few tens of nm) is much smaller tha...

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GW+Ttheory of excited electron lifetimes in metals

Cited by 80 publications

References 60 publications

Ultrafast magnetization enhancement in metallic multilayers driven by superdiffusive spin current

Ultrafast magnetization enhancement in metallic multilayers driven by superdiffusive spin current

Superconducting pairing mediated by spin fluctuations from first principles

Superdiffusive Spin Transport as a Mechanism of Ultrafast Demagnetization

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