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@INPROCEEDINGS{Freimuth:838610,
      author       = {Freimuth, Frank},
      title        = {{L}aser excitation of photocurrents in inversion asymmetric
                      ferromagnets},
      reportid     = {FZJ-2017-07187},
      year         = {2017},
      abstract     = {By breaking the inversion symmetry in crystals one enables
                      several mechanisms for photocurrent generation, which
                      otherwise would be forbidden by symmetry. First, there is
                      the circular photogalvanic effect [1,2], which has recently
                      attracted attention in noncentrosymmetric Weyl semimetals
                      [3,4]. Since most previous works on the circular
                      photogalvanic effect have focused on nonmagnetic
                      semiconductors, in this talk we will discuss this effect in
                      ferromagnetic metals. Second, when magnetic solids are
                      excited by femtosecond laser pulses, superdiffusive spin
                      currents are generated, which are converted into charge
                      currents by the inverse spin Hall effect [5,6]. Third,
                      photocurrents are also generated when magnetization dynamics
                      is excited by laser pulses, because magnetization dynamics
                      pumps electrical currents due to the inverse spin‐orbit
                      torque (ISOT) [7]. At small frequencies, i.e., under typical
                      FMR conditions, the inverse spin‐orbit torque can be
                      understood in terms of spin pumping combined with the spin
                      Hall effect and in terms of the Rashba or Dresselhaus
                      spin‐orbit fields [8,9,10,11]. However, when magnetic
                      solids are excited by femtosecond laser pulses, additional
                      effects set in, such as ultrafast demagnetization, which
                      lead to new mechanisms for generating electrical currents in
                      inversion asymmetric magnets. These photocurrents provide a
                      new tool to probe magnetization dynamics at subpicosecond
                      time scales. Using the Keldysh formalism we systematically
                      identify mechanisms behind the generation of electrical
                      currents in the range from FMR up to optical frequencies,
                      discovering also several new effects. In particular, we find
                      that not only precession of magnetization, but also
                      demagnetization, drives photocurrents [12]. Based on DFT
                      calculations we investigate these effects in Co/Pt and Mn/W
                      bilayers and elucidate the role that spin‐currents play.
                      The inverse Faraday effect (IFE) and the optical
                      spin‐transfer torque (OSTT) can be used to excite
                      magnetization dynamics by femtosecond laser pulses. We
                      present ab‐initio calculations of IFE and OSTT in Fe, Co
                      and FePt, compare the relative magnitude of IFE and OSTT in
                      these materials and discuss the disorder dependence[13].[1]
                      J. W. McIver et al., Nature Nanotechnology 7, 96 (2012) [2]
                      S. D. Ganichev and W. Prettl, JPCM 15, R935 (2003) [3] H.
                      Ishizuka et al., PRL 117, 216601 (2016) [4] Q. Ma et al.,
                      Nature Physics, DOI:10.1038/NPHYS4146 (2017) [5] T.
                      Kampfrath et al., Nature Nanotechnology 8, 256 (2013) [6] T.
                      Seifert et al., Nature Photonics 10, 483 (2016) [7] T. J.
                      Huisman et al., Nature Nanotechnology 11, 455 (2016)[8] F.
                      Freimuth, S. Blügel and Y. Mokrousov, PRB 90, 174423
                      (2014) [9] F. Freimuth, S. Blügel and Y. Mokrousov, JPCM
                      26, 104202 (2014) [10] F. Freimuth, S. Blügel and Y.
                      Mokrousov, PRB 92, 064415 (2015) [11] F. Freimuth, S.
                      Blügel and Y. Mokrousov, JPCM 28, 316001 (2016) [12] F.
                      Freimuth, S. Blügel and Y. Mokrousov, PRB 95, 094434
                      (2017) [13] F. Freimuth, S. Blügel and Y. Mokrousov, PRB
                      94, 144432 (2016)},
      month         = {Oct},
      date          = {2017-10-09},
      organization  = {Ultrafast Magnetism Conference,
                       Kaiserslautern (Germany), 9 Oct 2017 -
                       13 Oct 2017},
      subtyp        = {Other},
      cin          = {IAS-1 / PGI-1 / JARA-FIT / JARA-HPC},
      cid          = {I:(DE-Juel1)IAS-1-20090406 / I:(DE-Juel1)PGI-1-20110106 /
                      $I:(DE-82)080009_20140620$ / $I:(DE-82)080012_20140620$},
      pnm          = {142 - Controlling Spin-Based Phenomena (POF3-142)},
      pid          = {G:(DE-HGF)POF3-142},
      typ          = {PUB:(DE-HGF)6},
      url          = {https://juser.fz-juelich.de/record/838610},
}