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J. Krempaský V.N. Strocov L. Patthey M. Falub K. Hricovini 《Journal of Electron Spectroscopy and Related Phenomena》2010,181(1):63-69
Experiments directly probing the electronic states using angle-resolved photoemission (ARPES) were carried out on La2/3Sr1/3MnO3 in order to elucidate its electronic properties. ARPES is a surface sensitive technique where bulk and surface states are usually both present. We present high-resolution ARPES studies in the (1 0 0) and (1 1 0) mirror planes and compare them with simulated ARPES based on GGA + U band structure calculations. In the (1 1 0) mirror plane we identify surface umklapps accounted by surface reconstruction which couple to bulk electronic states. As predicted by the simulated spectra there is additional spectral intensity at the Fermi level detected in ARPES data due to k⊥-broadening effects in the photoemission final states. We demonstrate that this additional spectral intensity is a convenient spectral marker for determination of the kF Fermi momenta. 相似文献
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The Mn3s X-ray photoelectron spectra of manganites were studied. It was shown that for the formal valence of manganese from 3+ to 3.3+, the doping holes are O2p in character; as the valence of manganese increases further, the Mn3d states acquire holes. For La0.7Sr0.3MnO3, the Mn3p-3d resonance spectra provided information about the occupied and unoccupied Mn3d states, and the correlation energy U = 6.7 eV was determined experimentally. An analysis of X-ray dichroism on the L absorption spectra of three-dimensional La7/8Sr1/8MnO3 showed that the cooperative Jahn Teller distortion of the orthorhombic phase at 240 K was related to (x 2 ? z 2)/(y 2 ? z 2) type orbital ordering. 相似文献
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R. Bergamaschini F. Isa C.V. Falub P. Niedermann E. Müller G. Isella H. von Känel L. Miglio 《Surface Science Reports》2013,68(3-4):390-417
In this report we present a novel strategy in selective epitaxial growth on top of Si pillars, which results in a tessellated Ge film, composed by self-aligned micron-sized crystals in a maskless process. Modelling by rate equations the morphology evolution of fully facetted crystal profiles is extensively outlined, showing an excellent prediction of the peculiar role played by flux shielding among microcrystals, in the case of dense array configuration. Crack formation and substrate bending, caused by the mismatch in thermal expansion coefficients, are eliminated by the mechanical decoupling among individual microcrystals, which are also shown to be dislocation- and strain-free. The method has been also tested for Si1?xGex alloys, with compositions ranging from pure silicon to pure germanium. There are ample reasons to believe that this approach could be extended to other material combinations and substrate orientations, actually providing a technology platform for several device applications. 相似文献
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