Temporal decay of coherently optically injected charge and spin currents due to carrier–LO-phonon and carrier-carrier scattering

Duc, Huynh Thanh; Vu, Q. T.; Meier, Torsten; Haug, H.; Koch, S. W.

doi:10.1103/physrevb.74.165328

Cited by 27 publications

(20 citation statements)

References 41 publications

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“…However, as shown in Ref. [27] the nonresonant intraband acceleration induced by an optical field appears as an intermediate step in a perturbative analysis of two-color photocurrents. Unlike in centrosymmetric bulk semiconductors and semiconductor nanostructures, the break of inversion symmetry at the surface opens up additional excitation pathways because interband transitions are allowed between all bands even in dipole approximation.…”

Section: Resultsmentioning

confidence: 97%

“…Since this resonant process is induced only by the high-frequency part of the two-color laser field the generated population does not depend on the relative phase ΔΦ and thus provides a phase-independent background. (ii) asymmetric k-space distributions, i.e., photocurrents, are generated in third order if besides two optical interband transitions also a intraband excitation is considered [27]. In the equations of motion, the intraband excitation process is proportional to a derivative with respect to the wave vector k and therefore this pathway leads to an antisymmetric k-space occupation [27].…”

Section: Resultsmentioning

confidence: 99%

“…This process works in centrosymmetric and noncentrosymmetric materials. For semiconductor nanostructures, a microscopic theory has been developed that provides a detailed description of the ultrafast dynamics of the optical excitations and the photocurrents including many-body effects and scattering processes [26][27][28]. This approach is based on the semiconductor Bloch equations [29] which are extended by the electric field induced intraband acceleration [26,30].…”

Section: Resultsmentioning

confidence: 99%

“…(ii) asymmetric k-space distributions, i.e., photocurrents, are generated in third order if besides two optical interband transitions also a intraband excitation is considered [27]. In the equations of motion, the intraband excitation process is proportional to a derivative with respect to the wave vector k and therefore this pathway leads to an antisymmetric k-space occupation [27]. The direction of the k-space asymmetry and thus of the photocurrent is proportional to sin(ΔΦ).…”

Section: Resultsmentioning

confidence: 99%

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Generation and time‐resolved detection of coherently controlled electric currents at surfaces

Güdde

Rohleder

Meier

et al. 2009

Phys. Status Solidi (c)

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We demonstrate a technique for the generation and detection of electron currents at surfaces on a femtosecond time scale with a contact‐free experimental setup based on a combination of coherent control and photoemission spectroscopy. We have applied this technique for electrons excited into image‐potential states on a Cu(100) surface that form a free‐electron‐like band in the direction parallel to the surface. The photogeneration of currents is described by optical Bloch equations for a multiband model. By incorporating field‐induced interband and intersubband transitions together with intraband accelerations into the model, the observed phase dependence of the population and of the current can be reproduced. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

Generation and time‐resolved detection of coherently controlled electric currents at surfaces

Güdde

Rohleder

Meier

et al. 2009

Phys. Status Solidi (c)

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“…19 Microscopically the acceleration of the excited electrons or holes by the electric fields of the laser pulses can be described by taking into account that optical dipole transitions in solids include contributions of intraband transitions within electronic bands, which change the electron momentum. [19][20][21] This can be seen by evaluating the matrix element of the dipole operator d = −er for Bloch states of an electron with momentum k in a band λ as λ, k|d|λ , k = er λλ…”

Section: Modeling Of the Coherent Excitationmentioning

confidence: 99%

Ultrafast coherent control of electric currents at metal surfaces

et al. 2010

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We report the development of an experimental technique to measure the dynamics of electrical currents on the femtosecond timescale. The technique combines methods of coherent control with time-and angle-resolved photoelectron spectroscopy. Direct snapshots of the momentum distribution of the excited electrons as function of time are then determined by photoelectron spectroscopy. In this way we gain information on the generation and decay of ultrashort current pulses in unprecedented detail. In particular, this technique allows the observation of elastic electron scattering in terms of an incoherent population dynamics in momentum space. We have applied this optical current generation and detection scheme to electrons in so-called image-potential states which represent a prototype of two-dimensional electronic surface states. Electrons in these states are bound perpendicular to the metal surface by the Coulombic image potential whereas they can move almost freely parallel to the surface. For the (n=1) image-potential state of Cu(100) we find a decay time of 10 fs due to electron scattering with steps and surface defects.

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Coherently Controlled Electrical Currents at Surfaces

Güdde

Rohleder

Meier

et al. 2010

Dynamics at Solid State Surfaces and Interfaces

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During the last decade, great progress has been made by investigating electron transport through single molecules, metallic point contacts, or chains of single atoms by using scanning tunneling microscopy or break junctions [1,2]. Many of these works have focused on the coherent regime where inelastic scattering of the electrons due to vibronic or electronic excitation within the junction can be neglected. In this regime, nanoscale wires show no ohmic behavior and a quantization of the conductance has been observed as can be described by the Landauer theory [3]. While these experiments observe electron transport on the atomic scale, information about the dynamics of electron transport on the timescale of the relevant scattering mechanisms is scarce. The microscopic understanding of the mechanisms of electron transport, however, is not only of great interest for the development of new small-scale electronic devices, the connection of the electric conductivity s of a material with the microscopic scattering processes of individual charge carriers is also a fundamental issue, central to solid state physics [4]. This question goes back to Paul Drude [5] who has connected the electric conductivity s of a metal to an empirical scattering time t of free electrons that are accelerated in an external electric field, resulting in the well known Drude formula s ¼ e 2 n e t=m e , where e, m e , and n e are the electron charge, mass and density, respectively. Even if this model is oversimplified as it does not consider the quantum nature and the many-body aspects of electronelectron interaction, it gives the correct order of magnitude for the timescale of electron scattering processes. For Cu at room temperature, for example, it gives a scattering time of 27 fs [4], which shows that usual conductivity measurements cannot resolve the individual scattering events because available electronic equipment can neither produce trigger signals nor detect transients that are shorter than tens of picoseconds.Recently, we have introduced a new experimental technique that is capable of accessing the dynamics of electrical currents on the femtosecond timescale [6]. This contact-free technique combines the pure optical generation of electric

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Temporal decay of coherently optically injected charge and spin currents due to carrier–LO-phonon and carrier-carrier scattering

Cited by 27 publications

References 41 publications

Generation and time‐resolved detection of coherently controlled electric currents at surfaces

Generation and time‐resolved detection of coherently controlled electric currents at surfaces

Ultrafast coherent control of electric currents at metal surfaces

Coherently Controlled Electrical Currents at Surfaces

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