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Pfalzer, P.; Will, Judith; Nateprov, A. A.; Klemm, Matthias; Eyert, V.; Horn, S.; Frenkel, Anatoly I.; Calvin, S.; denBoer, M. L.

doi:10.1103/physrevb.66.085119

Cited by 10 publications

(15 citation statements)

References 29 publications

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“…These insulating phases have a similar electronic structure. 39,41 A comparable modification of the spectral shape occurs for the bare V 2 O 3 ͑1120͒ layer at the PM-to-AFI phase transition ͑Fig. 7, left panel͒.…”

Section: B Microscopic Properties Of Fe Co and V In Fe"co… /V 2 O mentioning

confidence: 80%

Magnetic and electronic interaction effects at the interfaces ofFe∕V2O3andCo

et al. 2005

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Thin films of V 2 O 3 ͑1120͒ can exist in metallic and insulating phases with different magnetic properties, similar as the bulk single crystals. We have used macroscopic magnetometry and x-ray absorption spectroscopy together with magnetic circular dichroism to show that when these films are combined with thin overlayers of bcc Fe and hcp Co, this has a pronounced impact on the electronic and magnetic properties of the interfaces. While the uncovered oxide is metallic at room temperature, both ferromagnets induce an insulating phase near the surface of the oxide, presumably due to hybridization effects at the interface. Remarkably, the electronic interaction across the interface is significantly different for the two systems. This is reflected in a magnetically "dead" atomic layer in the Fe films at the interface, a property not observed in the Co films. As a consequence the magnetic anisotropy of the two ferromagnets is dissimilar. In the antiferromagnetic phase of V 2 O 3 , at T Ͻ T N Ϸ 160 K, the hysteresis loops of the Co films exhibit a significant exchange bias; the effect is absent for Fe. The faceted surface structure of the V 2 O 3 ͑1120͒ layers induces a uniaxial magnetic anisotropy with magnetocrystalline and magnetostatic contributions in both ferromagnetic overlayers.

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Section: B Microscopic Properties Of Fe Co and V In Fe"co… /V 2 O mentioning

confidence: 80%

Magnetic and electronic interaction effects at the interfaces ofFe∕V2O3andCo

et al. 2005

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“…This procedure allows one to separate scattering paths along and perpendicular to the hexagonal c axis as detailed in Ref. 5.…”

Section: Methodsmentioning

confidence: 99%

Structural precursor to the metal-insulator transition inV2O3

et al. 2006

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The temperature dependence of the local structure of V 2 O 3 in the vicinity of the metal-to-insulator transition ͑MIT͒ has been investigated using hard x-ray absorption spectroscopy. It is shown that the vanadium pair distance along the hexagonal c axis changes abruptly at the MIT as expected. However, a continuous increase of the tilt of these pairs sets in already at higher temperatures and reaches its maximum value at the onset of the electronic and magnetic transition. These findings confirm recent theoretical results which claim that electron-lattice coupling is important for the MIT in V 2 O 3 . Our results suggest that the distortion of the symmetry of the basal plane plays a decisive role for the MIT and orbital degrees of freedom drive the MIT via changes in hybridization.

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“…The details of the techniques using these x-ray spectroscopy methods to study local structure of materials can be found in Refs. [25][26][27][28][29][30][31][32]. XANES experiments ͑beamline X11A at NSLS͒ were mainly focused on the Ti K edge to examine its possible off-center displacement while the EXAFS data were collected for all three cations ͑K edge of Cu, Ti at beamline X11A and Ca at beamline X15B, NSLS͒ to measure the cation short-range order.…”

Section: B Synchrotron X-ray Diffractionmentioning

confidence: 99%

Nanoscale disorder and local electronic properties ofCaCu3Ti4O12: An integrated study of electron, neutron, and x-ray diffraction, x-ray absorption fine struct

Zheng

Frenkel

et al. 2010

Phys. Rev. B

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We report a combined experimental and theoretical study of CaCu 3 Ti 4 O 12 . Based on our experimental observations of nanoscale regions of Ca-Cu antisite defects in part of the structure, we carried out densityfunctional theory ͑DFT͒ calculations that suggest a possible electronic mechanism to explain the gigantic dielectric response in this material. The defects are evident in atomically resolved transmission electron microscopy measurements, with supporting evidence from a quantitative analysis of the electron diffraction and DFT which suggests that such defects are reasonable on energetic grounds. To establish the extent of the defects, bulk average measurements of the local structure were carried out: extended x-ray absorption fine structure ͑EXAFS͒, atomic pair-distribution function analysis of neutron powder-diffraction data, and singlecrystal x-ray crystallography. The EXAFS data are consistent with the presence of the nanoclustered defects with an estimate of less than 10% of the sample being disordered while the neutron powder-diffraction experiments place an upper of ϳ5% on the proportion of the sample in the defective state. Because of the difficulty of quantifying nanoscale defects at such low levels, further work will be required to establish that this mechanism is operative in CaCu 3 Ti 4 O 12 but it presents a nontraditional plausible avenue for understanding colossal dielectric behavior.

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Local symmetry breaking in paramagnetic insulating(Al,V)2O3

Cited by 10 publications

References 29 publications

Magnetic and electronic interaction effects at the interfaces ofFe∕V2O3andCo

Magnetic and electronic interaction effects at the interfaces ofFe∕V2O3andCo

Structural precursor to the metal-insulator transition inV2O3

Nanoscale disorder and local electronic properties ofCaCu3Ti4O12: An integrated study of electron, neutron, and x-ray diffraction, x-ray absorption fine struct

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