排序方式: 共有51条查询结果,搜索用时 125 毫秒
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Mizokawa T Tjeng LH Sawatzky GA Ghiringhelli G Tjernberg O Brookes NB Fukazawa H Nakatsuji S Maeno Y 《Physical review letters》2001,87(7):077202
O 1s x-ray absorption study of the Mott insulator Ca(2)RuO(4) shows that the orbital population of the 4d t(2g) band dramatically changes with temperature. In addition, spin-resolved circularly polarized photoemission study of Ca(2)RuO(4) shows that a substantial orbital angular momentum is induced in the Ru 4d t(2g) band. Based on the experimental results and model Hartree-Fock calculations, we argue that the cooperation between the strong spin-orbit coupling in the Ru 4d t(2g) band and the small distortion of the RuO(6) octahedra causes the interesting changeover of the spin and orbital anisotropy as a function of temperature. 相似文献
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Koethe TC Hu Z Haverkort MW Schüssler-Langeheine C Venturini F Brookes NB Tjernberg O Reichelt W Hsieh HH Lin HJ Chen CT Tjeng LH 《Physical review letters》2006,97(11):116402
We present a detailed study of the valence and conduction bands of VO2 across the metal-insulator transition using bulk-sensitive photoelectron and O K x-ray absorption spectroscopies. We observe a giant transfer of spectral weight with distinct features that require an explanation which goes beyond the Peierls transition model as well as the standard single-band Hubbard model. Analysis of the symmetry and energies of the bands reveals the decisive role of the V 3d orbital degrees of freedom. Comparison to recent realistic many body calculations shows that much of the k dependence of the self-energy correction can be cast within a dimer model. 相似文献
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We find using local spin density approximation + Hubbard U band structure calculations that the novel one-dimensional cobaltate Ca3Co2O6 is not a ferromagnetic half-metal but a Mott insulator. Both the octahedral and the trigonal Co ions are formally trivalent, with the octahedral being in the low-spin and the trigonal in the high-spin state. The inclusion of the spin-orbit coupling leads to the occupation of the minority-spin d2 orbital for the unusually coordinated trigonal Co, producing a giant orbital moment (1.57 microB). It also results in an anomalously large magnetocrystalline anisotropy (of order 70 meV), elucidating why the magnetism is highly Ising-like. The role of the oxygen holes, carrying an induced magnetic moment of 0.13 microB per oxygen, for the exchange interactions is discussed. 相似文献
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Ackerbauer SV Senyshyn A Borrmann H Burkhardt U Ormeci A Rosner H Schnelle W Gamża M Gumeniuk R Ramlau R Bischoff E Schuster JC Weitzer F Leithe-Jasper A Tjeng LH Grin Y 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(20):6272-6283
The synthesis and a joint experimental and theoretical study of the crystal structure and physical properties of the new ternary intermetallic compound TiGePt are presented. Upon heating, TiGePt exhibits an unusual structural phase transition with a huge volume contraction of about 10?%. The transformation is characterized by a strong change in the physical properties, in particular, by an insulator-metal transition. At temperatures below 885?°C TiGePt crystallizes in the cubic MgAgAs (half-Heusler) type (LT phase, space group F43m, a = 5.9349(2)??). At elevated temperatures, the crystal structure of TiGePt transforms into the TiNiSi structure type (HT phase, space group Pnma, a = 6.38134(9)??, b = 3.89081(5)??, c = 7.5034(1)??). The reversible, temperature-dependent structural transition was investigated by in-situ neutron powder diffraction and dilatometry measurements. The insulator-metal transition, indicated by resistivity measurements, is in accord with band structure calculations yielding a gap of about 0.9?eV for the LT phase and a metallic HT phase. Detailed analysis of the chemical bonding in both modifications revealed an essential change of the Ti-Pt and Ti-Ge interactions as the origin of the dramatic changes in the physical properties. 相似文献
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JianFa Zhao Li Peng Cao WenMin Li Jun Zhang GuangYang Dai Shuang Yu QingQing Liu XianCheng Wang GuoQiang Zhao YaTing Jia Lei Duan YouWen Long Hong-Ji Lin Chien-Te Chen Liu-Hao Tjeng ZhiWei Hu RunZe Yu ChangQing Jin 《中国科学:物理学 力学 天文学(英文版)》2019,(10)
正The discovery of high-temperature copper oxide superconductors(HTS)by Bednorz and Muller[1]in 1986 opened up a new field of superconductivity.Since then,several different families of materials have been discovered with greatly increased superconducting critical temperature(T_c)[2].Oxychloride cuprates,Ca_(n+1)Cu_nO_(2n)Cl_2,are one such type of 相似文献
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Zhao JianFa Cao LiPeng Li WenMin Zhang Jun Dai GuangYang Yu Shuang Liu QingQing Wang XianCheng Zhao GuoQiang Jia YaTing Duan Lei Long YouWen Lin Hong-Ji Chen Chien-Te Tjeng Liu-Hao Hu ZhiWei Yu RunZe Jin ChangQing 《中国科学:物理学 力学 天文学(英文版)》2019,62(10):1-5
We present a first-principles investigation on the dynamics and mechanism of the oxidation reaction between water molecules and the reduced PuO_2(110) surface using ab initio molecular dynamics(AIMD) simulations in combination with density functional theory(DFT) + U calculations. We find a dominating dissociation preference of water molecules for the vacancy defect sites on the PuO_2(110) surface, irrespective of the water or vacancy coverage. Due to hybridizations between the frontier orbitals of water molecule and the electronic states of the vacancy vicinity, partial water dissociation at the vacancy sites is exothermic and barrierless. The dissociation product, an OH group, further hydrogenates the PuO_2(110) surface by occupying the vacancy site.We also observe surface vacancy diffusion induced by the interactions between the water molecules and the surface oxygen atom in the proximity of the defect sites. 相似文献
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Sr2MgOsO6: A Frustrated Os6+ (5d2) Double Perovskite with Strong Antiferromagnetic Interactions 下载免费PDF全文
Angelina Sarapulova Peter Adler Walter Schnelle Daria Mikhailova Claudia Felser Liu Hao Tjeng Martin Jansen 《无机化学与普通化学杂志》2015,641(5):769-771
The Os6+ (t2g2) double perovskite Sr2MgOsO6 was prepared as polycrystalline material from the respective binary metal oxides. Sr2MgOsO6 crystallizes with the tetragonal space group I4/m. Magnetization and specific heat measurements show a broad anomaly near 100 K, but no well‐defined cusp. The magnetism is governed by strong antiferromagnetic interactions. Sr2MgOsO6 constitutes a new example for the peculiar, poorly understood magnetism of 5d2 ions on a frustrated fcc lattice, where spin‐orbit coupling and orbital physics are expected to play an important role. 相似文献