ZfN: Search Results

1	Author	M. Tei, H. Takai, K. Mizoguchi, K. Kume	Requires cookie*
	Title	Cu NQR Study on Transverse Relaxation Rate below T c in YBa 2 Cu 3 0 7
	Abstract	The transverse relaxation rate T 2 l was measured in YBa 2 Cu 3 0 7 from 4.2 to 100 K in zero magnetic field. It showed a sudden drop just below T c down to 1/3 of that above T c . A cusp-shaped sharp peak of Tf 1 was found at 35 K for Cu(2) (plane) site, but not for Cu(l) (chain) site. Except the peak, all the behavior can be interpreted by the model of Pennington et al. that the origin of T 2 1 at 100 K is mainly the local field fluctuation by the Cu d-electron and secondly the indirect nuclear spin-spin coupling via superexchange interaction between Cu-ions. Below T c the former is sup-pressed.
	Reference	Z. Naturforsch. 45a, 429—432 (1990); received August 22 1989 in revised form October 30 1989
	Published	1990
	Keywords	Nuclear quadrupole resonance, High T c superconductor, Transverse relaxation rate, Super-exchange interaction, Electron spin fluctuation
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	TEI-XML for	default:Reihe_A/45/ZNA-1990-45a-0429.pdf
	Identifier	ZNA-1990-45a-0429
	Volume	45

2	Author	L. C. Smedskjaer, A. Bansil	Requires cookie*
	Title	Positron Annihilation Studies of the Electronic Structure and Fermiology of High-Tc Superconductors
	Abstract	We discuss the application of the positron annihilation angular correlation (ACAR) spectroscopy for investigating the electronic structure and Fermiology of high-T c superconductors, with focus on the YBa 2 Cu 3 O v system where most of the experimental and theoretical work has to date been concentrated. Detailed comparisons between the measured 2 D-ACAR positron spectra and the corresponding band theory predictions show a remarkable agreement (for the normal state), indicat-ing that the electronic structure and Fermi surface of this material is described reasonably by the conventional picture.
	Reference	Z. Naturforsch. 48a, 398—405 (1993); received January 25 1992
	Published	1993
	Keywords	Positron annihilation, Angular correlation of annihilation radiation (ACAR), Electron momentum density, High-T c superconductors
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	TEI-XML for	default:Reihe_A/48/ZNA-1993-48a-0398.pdf
	Identifier	ZNA-1993-48a-0398
	Volume	48