T. Lorenz
University of Cologne
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Featured researches published by T. Lorenz.
Physical Review B | 2002
C. Zobel; M. Kriener; D. Bruns; J. Baier; M. Grüninger; T. Lorenz; P. Reutler; A. Revcolevschi
We present measurements of the magnetic susceptibility and of the thermal expansion of a LaCoO 3 single crystal. Both quantities show a strongly anomalous temperature dependence. Our data are consistently described in terms of a spin-state transition of the Co 3 + ions with increasing temperature from a low-spin ground state (t 6 2 g e 0 g ) to an intermediate-spin state (t 5 2 g e 1 g ) without (100-500 K) and with (>500 K) orbital degeneracy. We attribute the lack of orbital degeneracy up to 500 K to (probably local) Jahn-Teller distortions of the CoO 6 octahedra. A strong reduction or disappearance of the Jahn-Teller distortions seems to arise from the insulator-to-metal transition around 500 K.
Physical Review B | 2004
M. Kriener; C. Zobel; A. Reichl; J. Baier; M. Cwik; K. Berggold; H. Kierspel; O. Zabara; A. Freimuth; T. Lorenz
We present an investigation of the influence of structural distortions in charge-carrier doped
Physical Review B | 2003
G. Maris; Y. Ren; Volotchaev; C. Zobel; T. Lorenz; Thomas Palstra
{\mathrm{La}}_{1\ensuremath{-}x}{M}_{x}{\mathrm{CoO}}_{3}
Physical Review B | 2005
J. Baier; S. Jodlauk; M. Kriener; A. Reichl; C. Zobel; H. Kierspel; A. Freimuth; T. Lorenz
by substituting
Physical Review Letters | 2004
Z. Hu; Hua Wu; M. W. Haverkort; H. H. Hsieh; H.-J. Lin; T. Lorenz; J. Baier; A. Reichl; I. Bonn; C. Felser; A. Tanaka; C. T. Chen; L. H. Tjeng
{\mathrm{La}}^{3+}
Physical Review B | 2005
K. Berggold; M. Kriener; C. Zobel; A. Reichl; M. Reuther; R. MüLLER; A. Freimuth; T. Lorenz
with alkaline-earth metals of strongly different ionic sizes, that is,
Journal of Physics: Condensed Matter | 2007
S Jodlauk; P. Becker; J A Mydosh; D. I. Khomskii; T. Lorenz; S. V. Streltsov; Dominik C. Hezel; L. Bohatý
M={\mathrm{Ca}}^{2+},
Journal of Physics: Condensed Matter | 2006
O. Heyer; N. Hollmann; I Klassen; S Jodlauk; L. Bohatý; P. Becker; J A Mydosh; T. Lorenz; D. I. Khomskii
Nature | 2002
T. Lorenz; M. Hofmann; M. Grüninger; A. Freimuth; Goetz S. Uhrig; M. Dumm; Martin Dressel
{\mathrm{Sr}}^{2+},
Physical Review B | 2003
M. Cwik; T. Lorenz; J. Baier; R. MüLLER; G. André; F. Bourée; F. Lichtenberg; A. Freimuth; Robert Schmitz; E. Müller-Hartmann; M. Braden
and