Ultrafast magnetization dynamics in the half‐metallic Heusler alloy Co2Cr0.6Fe0.4Al

Ultrafast demagnetization upon excitation with intense laser pulses has been observed for a variety of ferromagnetic materials. In half‐metals, long demagnetization times are expected due to the band gap for one spin direction. We have investigated the theoretically half‐metallic Heusler alloy Co2Cr0.6Fe0.4Al (CCFA), using the time‐resolved magnetooptical Kerr effect. A demagnetization time in the range of typical transition metal ferromagnets with lower spin polarization has been found, while magnetization recovery proceeds on a slower time scale. The results are discussed in the context of recent models and experimental results. We propose that for Heusler alloys the initial stage of recovery could be a better measure for the spin polarization than the demagnetization time. A simple estimate leads to a bulk spin polarization value of 0.86 for CCFA.

[1]  Georg Weidenspointner,et al.  In vivo protein crystallization opens new routes in structural biology , 2012, Nature Methods.

[2]  M. Cinchetti,et al.  Band-structure-dependent demagnetization in the Heusler alloy Co₂Mn(1-x)FexSi. , 2010, Physical review letters.

[3]  L. Sandratskii,et al.  Ultrafast magnon generation in an Fe film on Cu(100). , 2010, Physical review letters.

[4]  Burkard Hillebrands,et al.  Magnetic anisotropy, exchange and damping in cobalt-based full-Heusler compounds: an experimental review , 2010 .

[5]  M. Münzenberg,et al.  Evidence for thermal mechanisms in laser-induced femtosecond spin dynamics , 2010 .

[6]  H. Padmore,et al.  Time-resolved demagnetization of Co2MnSi observed using x-ray magnetic circular dichroism and an ultrafast streak camera , 2010, Journal of physics. Condensed matter : an Institute of Physics journal.

[7]  R. Hicken,et al.  Optically induced magnetization dynamics and variation of damping parameter in epitaxial Co2MnSi Heusler alloy films , 2010 .

[8]  M. Cinchetti,et al.  Explaining the paradoxical diversity of ultrafast laser-induced demagnetization. , 2010, Nature materials.

[9]  T. Miyazaki,et al.  Ultrafast demagnetization for Ni80Fe20 and half-metallic Co2MnSi heusler alloy films , 2010 .

[10]  Martin Aeschlimann,et al.  Ultrafast demagnetization dynamics at the M edges of magnetic elements observed using a tabletop high-harmonic soft x-ray source. , 2009, Physical review letters.

[11]  M. Cinchetti,et al.  Ultrafast demagnetization of ferromagnetic transition metals: The role of the Coulomb interaction , 2009, 0906.5104.

[12]  M. Cinchetti,et al.  Effects of post-growth annealing on structural and compositional properties of the Co2Cr0.6Fe0.4Al surface and its relevance for the surface electron spin polarization , 2009 .

[13]  Martin Jourdan,et al.  Morphology induced magnetoresistance enhancement of tunneling junctions with the Heusler electrode Co2Cr0.6Fe0.4Al , 2009 .

[14]  D. Steiauf,et al.  Elliott-Yafet mechanism and the discussion of femtosecond magnetization dynamics , 2009 .

[15]  K. Matsuda,et al.  Half-metallic electronic structure of Co2MnSi electrodes in fully epitaxial Co2MnSi/MgO/Co2MnSi magnetic tunnel junctions investigated by tunneling spectroscopy (invited) , 2009 .

[16]  Andy Thomas,et al.  Spin polarization in half-metals probed by femtosecond spin excitation. , 2009, Nature materials.

[17]  S. Silvestri,et al.  Dynamics of electron-magnon interaction and ultrafast demagnetization in thin iron films , 2008 .

[18]  C. Felser,et al.  Conversion electron Mössbauer spectroscopy of epitaxial Co2Cr0.6Fe0.4Al thin films , 2008 .

[19]  N. Tezuka,et al.  Site disorder inCo2Fe(Al,Si)Heusler alloys and its influence on junction tunnel magnetoresistance , 2008 .

[20]  M. Jourdan,et al.  Tunneling spectroscopy of the Heusler compound Co2Cr0.6Fe0.1Al , 2007 .

[21]  W. Eberhardt,et al.  Femtosecond modification of electron localization and transfer of angular momentum in nickel. , 2007, Nature materials.

[22]  A. Gloskovskii,et al.  Correlation of local disorder and electronic properties in the Heusler alloy Co2Cr0.6Fe0.4Al , 2007 .

[23]  T. Marukame,et al.  Fabrication of exchange-biased epitaxial magnetic tunnel junctions with a heusler alloy Co2Cr0.6Fe0. 4Al thin film , 2007 .

[24]  X. Liu,et al.  Ultrafast enhancement of ferromagnetism via photoexcited holes in GaMnAs. , 2007, Physical review letters.

[25]  M. Jourdan,et al.  Epitaxial Co2Cr0.6Fe0.4Al thin films and magnetic tunnelling junctions , 2006, cond-mat/0612022.

[26]  M. Cinchetti,et al.  Towards a full Heusler alloy showing room temperature half-metallicity at the surface , 2006, cond-mat/0609504.

[27]  M. Jourdan,et al.  Epitaxy of thin films of the Heusler compound Co2Cr0.6Fe0.4Al , 2006, cond-mat/0605698.

[28]  A. Nurmikko,et al.  Ultrafast spin-dynamics in half-metallic Cr O 2 thin films , 2006 .

[29]  K. Hono,et al.  Spin polarization of quaternary Co2Cr1-xFexAl Heusler alloys , 2006 .

[30]  B. Hillebrands,et al.  Magnetic anisotropies and magnetization reversal of the Co2Cr0.6Fe0.4Al Heusler compound , 2006, cond-mat/0606542.

[31]  H. Kubota,et al.  Giant tunneling magnetoresistance in Co2MnSi∕Al–O∕Co2MnSi magnetic tunnel junctions , 2006 .

[32]  M. Cinchetti,et al.  Spin-flip processes and ultrafast magnetization dynamics in Co: Unifying the microscopic and macroscopic view of femtosecond magnetism. , 2006, Physical review letters.

[33]  G. Schönhense,et al.  Electronic structure and spectroscopy of the quaternary Heusler alloy Co2Cr1−xFexAl , 2006, cond-mat/0601670.

[34]  B. Koopmans,et al.  Unifying ultrafast magnetization dynamics. , 2005, Physical review letters.

[35]  A. Yaresko,et al.  Theoretical study of the electronic and magnetic structures of the Heusler alloys Co2Cr1-xFexAl , 2005 .

[36]  M. Scheffler,et al.  Preserving the half-metallicity at the Heusler alloy Co2MnSi(001) surface: a density functional theory study. , 2005, Physical review letters.

[37]  B. Koopmans,et al.  Microscopic model for femtosecond magnetization dynamics , 2005 .

[38]  Yoshio Miura,et al.  Atomic disorder effects on half-metallicity of the full-Heusler alloys Co 2 ( Cr 1 − x Fe x ) Al : A first-principles study , 2004 .

[39]  H. Dürr,et al.  Femtosecond electron and spin dynamics in Ni/W(110) films. , 2003, Physical review letters.

[40]  D J Hilton,et al.  Optical orientation and femtosecond relaxation of spin-polarized holes in GaAs. , 2002, Physical review letters.

[41]  J. M. D. Coey,et al.  Half-metallic ferromagnetism: Example of CrO2 (invited) , 2002 .

[42]  R. Ulbrich,et al.  Ultrafast magneto-optical response of iron thin films , 2002 .

[43]  Kohlhepp,et al.  Ultrafast magneto-optics in nickel: magnetism or optics? , 2000, Physical review letters.

[44]  Charles G. Durfee,et al.  High power ultrafast lasers , 1998 .

[45]  Michael Bauer,et al.  ULTRAFAST SPIN-DEPENDENT ELECTRON DYNAMICS IN FCC CO , 1997 .

[46]  K. Bennemann,et al.  NONEQUILIBRIUM MAGNETIZATION DYNAMICS OF NICKEL , 1997, cond-mat/9707078.

[47]  Merle,et al.  Ultrafast spin dynamics in ferromagnetic nickel. , 1996, Physical review letters.

[48]  R. J. Elliott,et al.  Theory of the Effect of Spin-Orbit Coupling on Magnetic Resonance in Some Semiconductors , 1954 .