Electronic structure of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">CrO</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>as deduced from its magneto-optical Kerr spectra

Kuneš, J.; Novák, P.; Oppeneer, Peter M.; König, Christian; Fraune, Michael; Rüdiger, Ulrich; Güntherodt, G.; Draxl, Claudia

doi:10.1103/physrevb.65.165105

Cited by 28 publications

(18 citation statements)

References 40 publications

(33 reference statements)

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“…The electronic structure of CrO 2 has been extensively reported in the literature 16,17,18,19,20,21,22,23,25 so in this section we briefly discuss the density of states and compare with the ealier works. Figure 1 shows the density of states (spin up and down) of Cr-3d and O-2p states.…”

Section: Density Of States and Magnetic Momentsmentioning

confidence: 99%

“…These compounds serve as perspective materials in the field of spintronics 15 . Numerous theoretical works are available for CrO 2 explaining the electronic structure, bonding, optical and magneto-optical properties and magneto-crystalline anisotropy(MCA) etc 16,17,18,19,20,21,22,23,24,25 . Because of the uniaxial crystal structure, CrO 2 is expected to have a large magnetic anisotropy which makes it the favoured material for magneto-optical recording.…”

Section: Introductionmentioning

confidence: 99%

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Calculated electronic structure and x-ray magnetic circular dichroism of CrO₂

Kanchana¹,

Vaitheeswaran²,

Alouani³

2006

J. Phys.: Condens. Matter

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A detailed theoretical study on the electronic structure and magnetic properties of half-metallic ferromagnet CrO2 was carried out by means of relativistic full-potential linear muffin-tin orbital method within the generalized gradient approximation (GGA) to the exchange correlation potential. Our calculation favours the [001] magnetization axis to be the easy axis of magnetization when compared to the [100] axis which is in agreement with the experiments. The calculated spin and orbital magnetic moments of Cr agrees well with the experimental and other theoretical works. The Cr L2,3 x-ray absorption and x-ray magnetic circular dichroism (XMCD) spectra were calculated for both the quantization axis and compared with the experiment. In addition the oxygen K edge and XMCD spectra were also calculated which compares well with the experiments. The XMCD sum rules were used to compute the spin and orbital magnetic moments and results agree quite well with the direct calculation.

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Section: Density Of States and Magnetic Momentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Calculated electronic structure and x-ray magnetic circular dichroism of CrO₂

Kanchana¹,

Vaitheeswaran²,

Alouani³

2006

J. Phys.: Condens. Matter

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“…In the literature there are already some single results in this direction which, however, are in part contradictory. [5][6][7] We therefore have performed a systematic study, which is based on two different band-structure techniques and which takes a special care of the electronic orbital correlation effects ͑again by two different methods͒ which are not included in the commonly used local-spin-densityapproximation ͑LSDA͒ of the density-functional theory.…”

mentioning

confidence: 99%

Anisotropy of orbital moments and magnetic dipole termTzinCrO2:An
Komelj
¹
,
Ederer
²
,
Fähnle³
2004
Phys. Rev. B
14
7
6
0
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A systematic study is performed by the ab initio density-functional theory of the anisotropy of the orbital moments ͗l z ͘ and the magnetic dipole term ͗T z ͘ in bulk CrO 2 . Two different band-structure techniques are used ͑full potential linearized-augmented-plane-wave method and linear-muffin-tin-orbital method in the atomic-sphere approximation͒, and the electronic correlations are treated by the local-spin-density approximation ͑LSDA͒, the LSDAϩ orbital polarization method, and the LSDAϩU method. The calculated anisotropies of ͗l z ͘ and ͗T z ͘ are very large compared to Fe, Ni, and Co but still a factor of 5 and 2 smaller than the anisotropies obtained from a recently suggested analysis of the x-ray magnetic circular dichroism spectra for a thick layer of CrO 2 . DOI: 10.1103/PhysRevB.69.132409 PACS number͑s͒: 75.30.Gw, 71.15.Mb Recent research within the fields of magnetic tunneling and spin injection involves CrO 2 as a promising material for electrodes.1 Besides its potential importance for applications, this material also exhibits interesting physics originating from its half metallic nature and consequently the ferromagnetism due to the double-exchange coupling, 2 as well as from its orbital magnetism 3,4 which is related to the spinorbit coupling and the electronic orbital correlation effects. Consequently, there are already several experimental 3,4 and theoretical 4 -7 investigations of the orbital moments ͗l z ͘ in CrO 2 .However, much less information is available on the anisotropy of the orbital moments, i.e., on its dependence of the orientation of the sample magnetization ͑in the following the z axis of the external coordinate system is always chosen to be parallel to the magnetization direction͒. It has been pointed out first by Bruno 8 and later worked out in more detail by van der Laan 9 that the anisotropy of the orbital moment is closely related to the magnetocrystalline anisotropy energy. Furthermore, van der Laan has shown that there is an additional contribution to the anisotropy energy arising from the anisotropy of the magnetic dipole term T z , which is the expectation value of the magnetic dipole operator:In Eq. ͑1͒ r is the unit vector in the direction of the position vector r and is the vector of the Pauli matrices. In fact, it turns out ͑see below͒ that for CrO 2 the two contributions are very large and of similar magnitudes but opposite in sign.A suitable method to investigate the anisotropy of ͗l z ͘ and ͗T z ͘ is the angle-resolved variant 10 of the x-ray magnetic circular dichroism 11 ͑XMCD͒ which measures the XMCD spectra for various orientations of the sample magnetization.The orbital moments ͗l z ͘ then may be determined directly from the application of the XMCD orbital sum rule.12 In contrast, the application of the spin sum rule 13 yields a combination of the spin moment ͗ z ͘ and the ͗T z ͘ term. A separation of these two contributions is possible by applying the spin sum rule to XMCD spectra for various orientations of the sample magnetization. Cr atom in a thick l...

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“…On the other hand, the recent theoretical description of the experimental magneto-optical Kerr spectra of CrO 2 is best by not invoking an additional on-site Coulomb U correlation. 20 This point, obviously, needs further clarification.…”

mentioning

confidence: 99%

Room-temperature observation of high-spin polarization of epitaxial CrO2(100) island films at the Fermi energy

Dedkov

Fonine

König

et al. 2002

Applied Physics Letters

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Epitaxial CrO 2 (100) island films have been grown on TiO 2 (100) substrates by a chemical-vapor deposition technique. Well-controlled surface and interface properties of the CrO 2 (100) films were confirmed by scanning tunneling microscopy and transmission electron microscopy, respectively. Spin-and angle-resolved photoemission spectroscopy at room temperature revealed an energy gap of about 2 eV below Fermi level E F for spin-down electrons and a spin polarization of about ϩ95% at E F . After extended sputtering, the spin polarization can be recovered from about ϩ10% up to ϩ85% upon annealing. 1-3,7,10-13The HMF nature of CrO 2 has been predicted on the basis of the local-spin-density approximation ͑LSDA͒ to the density-functional theory.1,3 Only recently, spin polarization values of over 90% near E F were found for CrO 2 at 1.8 K using superconducting point contact spectroscopy, 7,11-13 although values of 95% had been obtained earlier by spinpolarized photoemission at 293 K for binding energies of about 2 eV below E F .14 In this letter, we present a study of structural properties and of the spin-dependent electronic structure of epitaxial CrO 2 (100) island films prepared on isostructural TiO 2 (100) substrates by a chemical-vapor deposition ͑CVD͒ technique. 15 The CrO 2 (100) surface shows in scanning tunneling microscopy ͑STM͒ the growth of large elongated rectangular-like epitaxial islands with a preferential growth direction along the in-plane ͓001͔ axis. A sharp CrO 2 (100)/TiO 2 (100) interface without intermixing and a good crystalline quality of CrO 2 (100) were found by transmission electron microscopy ͑TEM͒. The spin-dependent electronic structure of the CrO 2 (100) films has been investigated at 293 K by means of spin-and angle-resolved photoemission spectroscopy ͑PES͒. Below the Fermi level E F an energy gap of about 2 eV was observed for spin-down electrons, and thus a spin polarization of up to ϩ95% at E F was found at 293 K. Both the magnitude of the spin-down gap and the value of the spin polarization are in good agreement with theoretical band-structure calculations, which predict only majority spin electrons at E F .1,3 Sputtering of the asprepared surface up to 210 s increases the spin polarization from ϩ80% to ϩ95%. Continued sputtering up to 750 s results in about ϩ10% spin polarization, which can be increased again up to ϩ85% by annealing for 12 h at 150°C in ultrahigh vacuum ͑UHV͒.The CrO 2 (100) films were prepared by a CVD technique proposed by Ishibashi.15 As substrates isostructural TiO 2 (100) ͑rutile; aϭ4.592 Å; cϭ2.959 Å; space group: P4 2 /mnm͒ has been used. CrO 3 is decomposed at a temperature of 260°C within a two-zone tube furnace. A wellcontrolled oxygen flow ͑0.5 l/min͒ transports the decomposed precursor material (CrO 3 ) and its related oxide phases (Cr 2 O 5 , Cr 3 O 8 ) into the deposition zone where the substrate is placed. The substrate temperature is adjusted to 390°C enabling the epitaxial growth of CrO 2 . Immediately after the growth the CrO 2 (100) films were i...

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Electronic structure ofCrO2as deduced from its magneto-optical Kerr spectra

Cited by 28 publications

References 40 publications

Calculated electronic structure and x-ray magnetic circular dichroism of CrO₂

Calculated electronic structure and x-ray magnetic circular dichroism of CrO₂

Anisotropy of orbital moments and magnetic dipole termTzinCrO2:An
Komelj
¹
,
Ederer
²
,
Fähnle³
2004
Phys. Rev. B
14
7
6
0
View full text Add to dashboard Cite

Room-temperature observation of high-spin polarization of epitaxial CrO2(100) island films at the Fermi energy

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Electronic structure ofCrO2as deduced from its magneto-optical Kerr spectra

Cited by 28 publications

References 40 publications

Calculated electronic structure and x-ray magnetic circular dichroism of CrO2

Calculated electronic structure and x-ray magnetic circular dichroism of CrO2

Anisotropy of orbital moments and magnetic dipole termTzinCrO2:AnKomelj1, Ederer2, Fähnle3 2004Phys. Rev. B14760View full textAdd to dashboardCite

Room-temperature observation of high-spin polarization of epitaxial CrO2(100) island films at the Fermi energy

Contact Info

Product

Resources

About

Calculated electronic structure and x-ray magnetic circular dichroism of CrO₂

Calculated electronic structure and x-ray magnetic circular dichroism of CrO₂

Anisotropy of orbital moments and magnetic dipole termTzinCrO2:An
Komelj
¹
,
Ederer
²
,
Fähnle³
2004
Phys. Rev. B
14
7
6
0
View full text Add to dashboard Cite