Soft X-ray magnetic circular dichroism of Heusler-type alloy Co2MnGe

Miyamoto, Koji; Iori, K.; Kimura, Akio; Xie, Tian; Takeuchi, Masaki; Qiao, Shuang; Tsuchiya, Koichi

doi:10.1016/j.ssc.2003.08.007

Cited by 31 publications

(32 citation statements)

References 15 publications

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“…According to the site occupation model employed here (Table I) show a shoulder-like structure observed on the higher energy side of the Co L 3 -edge XAS, common to thin film bulk samples. 27,33 Co-oxide-like multiplet structures 20 were not observed for any samples, meaning that Co atoms were not oxidized even in the interfacial region, consistent with the previous report. 27 To determine the Co magnetic moment, we again used the sum rules 36,37 assuming the 3d hole number (n h ) to be 2.2.…”

Section: Resultssupporting

confidence: 91%

“…This mechanism was not considered by Picozzi et al 7 because they did not study such a heavily off-stoichiometric region as in our CMG samples, in which a large amount of Mn fills the Ge deficiencies. On the other hand, the deduced m spin (Co) for all the CMG samples is obviously larger than the theoretical value of the bulk sample, 1.06 μ B , and the experimental XMCD value of 1.04 μ B for the bulk samples reported by Miyamoto et al 33 Picozzi et al 7 theoretically investigated the effect of antisite defects in CMG and reported that the m spin (Co) of the Co Mn antisites in CMG was 1.35 μ B , which was larger than the 1.06 μ B for Co at the regular Co site. In the Co-rich region m spin (Co) ∼ 1.20 μ B , indicating the possible existence of Co Mn .…”

Section: Resultscontrasting

confidence: 72%

“…These features are characteristics observed for Co 2 MnSi and Co 2 MnGe. 33 In the XAS spectra for β = 1.40, 1.60, and 1.80, multiple fine structures were observed, implying that some of the interfacial Mn atoms are oxidized to Mn 2+ as reported in the previous work. 27 Therefore, we have subtracted the oxide component Mn 2+ -like multiplet structures such as MnO from the raw data for the β = 1.40, 1.60, and 1.80 films, as described in detail in the Appendix.…”

Section: Resultssupporting

confidence: 72%

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Effects of off-stoichiometry on the spin polarization at the Co2MnβGe0.38/MgO interfa

et al. 2012

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We have studied the electronic and magnetic states of Mn and Co atoms at the Co 2 Mn β Ge 0.38 (CMG)/MgO (β = 0.67-1.8) interfaces, which constitute CMG/MgO/CMG magnetic tunnel junctions, by means of x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroisms (XMCDs) at the Mn and Co L 2,3 edges and compared the deduced Co and Mn magnetic moments by the density-functional calculations with the coherent potential approximation (CPA). As the Mn content β increased, the intensity of Mn L 2,3 XMCD decreased, in agreement with the result of the CPA calculation, which showed the resultant reduction of charges and spin moment on Mn atoms because of the delocalization of Mn 3d electrons with increasing β. The Co spin magnetic moment for all the samples increased with decreasing β, again consistent with the present calculation and the previous density-functional calculation by Picozzi et al. that the Co Mn antisite has a larger magnetic moment than that of Co atoms at the regular sites and reduces the spin polarization at the Fermi level and hence the tunnel magnetoresistance ratio.

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Section: Resultssupporting

confidence: 91%

Section: Resultscontrasting

confidence: 72%

Section: Resultssupporting

confidence: 72%

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Effects of off-stoichiometry on the spin polarization at the Co2MnβGe0.38/MgO interfa

et al. 2012

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“…In comparison, the values that were extracted for Co 2 MnSi were roughly half those of Co 2 MnGe. 21 In summary, we have grown Co 2 MnSi thin films and determined that multiplet structure observed in the XAS spectra is likely a result of surface oxidation, although the shape of the XMCD spectrum remains essentially unaffected. A uniaxial and a fourfold magnetocrystalline anisotropy was observed in the films grown on GaAs ͑001͒.…”

Section: Resultsmentioning

confidence: 88%

“…These spectra are similar to those measured for Co 2 MnGe and other Mn-based intermetallic alloys. 20,21 The XMCD sum rules were used to determine the spin-orbit moment ratio for each atomic species, which is independent of Although absolute moments were not estimated in the study on Co 2 MnGe, the spin-orbit ratios were calculated to be ͑m orb / m spin ͒ = 0.10 and 0.04 for Co and Mn, respectively. In comparison, the values that were extracted for Co 2 MnSi were roughly half those of Co 2 MnGe.…”

Section: Resultsmentioning

confidence: 99%

Element-specific magnetic properties of Co2MnSi thin films

Stadler

Minott

Harley

et al. 2005

Journal of Applied Physics

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Co 2 MnSi thin films were grown on Al 2 O 3 ͑a plane͒ and GaAs ͑001͒ substrates and on thin silicon nitride windows using pulsed laser deposition. Angle-dependent magneto-optic Kerr effect measurements reveal both a uniaxial and a fourfold magnetocrystalline anisotropy for films grown on GaAs ͑001͒. X-ray magnetic circular dichroism spectra were measured at the L 2,3 edges of the thin films as a function of aluminum cap layer thickness, and transmission mode L 2,3 x-ray absorption through a 1000-Å Co 2 MnSi film grown on a silicon nitride membrane were measured, indicating that deviations from metalliclike spectra are likely due oxidation or contamination. Element-specific moments for Co and Mn were calculated from the X-ray magnetic circular dichroism data of a nonoxidized film.

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Phase Stability, Magnetic Properties, and Martensitic Transformations in Co‐Based Heusler Alloys

Umetsu

Kainuma

2020

Materials Science and Technology

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The phase stability, magnetic properties, electronic state, and martensitic transformation appearing in the L 2 1 ‐type ordered phase of Co‐based Heusler alloys are reviewed. Critical temperatures of the L 2 1 / B 2 order–disorder transition in stoichiometric Co 2 YZ ( Y = Ti, V, Cr, Mn, and Fe) alloys were experimentally estimated, and the degrees of order of the L 2 1 structure in stoichiometric Co 2 Y Ga alloys quenched from an elevated temperature were evaluated by powder neutron diffraction. All the experimental data are fundamentally consistent with the theoretical results based on the Bragg–Williams–Gorsky (BWG) approximation. The magnetic properties and electronic state for the stoichiometric Co 2 Y Ga alloys are briefly reviewed, and the concept of high‐field magnetic susceptibility, which is correlated to the characteristic feature of the density of states in the half‐metallic ferromagnets, is introduced. Martensitic transformations appearing in the nonstoichiometric Co‐based Heusler alloys are also presented and the phase stability is reviewed. In particular, the reentrant martensitic transformation in Co 2 Cr (Ga, Si) alloys is introduced together with some unique properties, such as cooling‐induced shape memory effect and inverse temperature dependence of the critical stress in the stress‐induced transformation.

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Soft X-ray magnetic circular dichroism of Heusler-type alloy Co2MnGe

Cited by 31 publications

References 15 publications

Effects of off-stoichiometry on the spin polarization at the Co2MnβGe0.38/MgO interfa

Effects of off-stoichiometry on the spin polarization at the Co2MnβGe0.38/MgO interfa

Element-specific magnetic properties of Co2MnSi thin films

Phase Stability, Magnetic Properties, and Martensitic Transformations in Co‐Based Heusler Alloys

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