1,721,032 research outputs found
Modelling of the reactive interface formation on Bi2Sr2CaCu2O8
No full textWe have applied the phenomenological model of diffused interfaces, developed originally to describe the Fe growth on Bi2Sr2CaCu2O8, to interpret quantitatively the core photoemission spectra of two reactive interfaces, namely Cr and Ge on Bi2Sr2CaCu2O8. At room temperature the interfaces with Fe and Cr have the same kinetics of growth suggesting similar adatom condensation, while the semiconductor-superconductor interface grows layer-by-layer according to the Franck-van der Merwe kinetics. Differences in the parameters of the model resulting from the simultaneous fit of the core-level decays are related to differences in the microscopic processes occurring during the growth
First order nucleation of charge ordered domains in La0.5Ca0.5MnO3 detected by 139La and 55Mn NMR
Full text linkThe local magnetism and charge ordering of La0.5Ca0.5MnO3, was investigated between room temperature and 1.3 K by means of La-139 and Mn-55 NMR. Antiferromagnetic and ferromagnetic domains are assigned unambiguously to the insulating charge ordered and the metallic state respectively. The phases are found to coexist at all temperatures below the first formation of a charge-ordered state. The two signal fractions display thermal and magnetic hysteresis, while their local fields and relaxations do not. These features and the absence of any critical behavior are characteristic of a first order F-AF transition, with ferromagnetic domains microscopically identical to the bulk metallic phase of the OM
Tunneling spectroscopy of Fe-doped YBa2Cu3O7 single crystals
No full textA comparison between the orthorhombic oxygen-deficient YBa2Cu3O7-Î ́ 60-K phase and the tetragonal YBa2(Cu0.96Fe0.04)3O7 system with Tc=57 K is made by means of tunnel junctions. No relevant differences are found in the behavior of the high-voltage gaplike structure at 25 mV while a suppression of the low-voltage structure at 5 mV is observed in the Fe-doped junctions. In some cases a zero-bias conductance peak is developed; this anomaly is analyzed in the framework of the Appelbaum-Kondo model for electron magnetic interactions. © 1992 The American Physical Society
SUBSTITUTIONS IN YBA2CU3O7-GAMMA AND THEIR INFLUENCE ON THE MAGNETIC PENETRATION DEPTH, ITS ANISOTROPY AND T-C - MUON SPIN ROTATION (MU-SR)
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Structural, transport, and electronic properties of a layered dichalcogenide AuVS2 with semimetallic properties
No full textWe report on preparation, crystal structure, transport properties, and ab initio band-structure calculations of the layered compound AuVS2. Single crystals of submillimeter size are obtained by reacting powders of BaVS3 with metallic gold at 700 degreesC under an hydrostatic pressure of 3 GPa. According to single-crystal x-ray-diffraction data, the crystal structure is hexagonal with unit-cell parameters a=b=3.224+/-0.001 Angstrom, c=15.039+/-0.002 Angstrom, and space-group symmetry P6(3)/mmc. Temperature-dependent ac resistivity measurements yield a value of room-temperature in-plane resistivity rho(ab)approximate to400 muOmega cm and show a slightly metallic temperature dependence above 250 K. Below this temperature the dependence becomes weakly insulating but the resistivity remains less than or similar to800 muOmega cm at 4.2 K. This behavior is in agreement with the above band-structure calculations which indicate that AuVS2 is a semimetal with an almost vanishing density of states at the Fermi level. Both electron and hole doping would strongly enhance the metallic properties and change the very small Fermi surfaces of the undoped compound into larger pockets with mostly V 3d character
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