ESR of Gd3+ and Er3+ in Pr2-xCexCuO4
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1995-01-01
Autores
Martins, G. B.
Rao, D.
Valdivia, J. A.
Pires, M. A.
Barberis, G. E.
Rettori, C.
Venegas, P. A. [UNESP]
Oseroff, S.
Fisk, Z.
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Electron spin resonance (ESR) of Gd3+ and Er3+ in single crystals of Pr2-xCexCuO4 (0≤x≤0.15) at liquid-helium temperature shows crystal field (CF) effects corresponding to a C4v point symmetry. Upon doping with Ce4+, a reduction of about 23% in the second-order CF parameter b20 is found with no significant change for the other CF spin-Hamiltonian parameters. The resonance lines broaden and present a Dysonian line shape at higher Ce4+ concentration, which is consistent with an increase in the CF inhomogeneity and the metallic character of the compound. Magnetic-susceptibility measurements present a small increase in the low-temperature anisotropy upon doping, consistent with a smaller B02 crystal-field parameter for Pr3+ in Pr2-xCexCuO4. The reduction in the CF parameters is tentatively attributed to charge transfer from Ce atoms to the CuO2 planes. The exchange parameters jGd-Pr and jPr-Pr are estimated from the ESR and susceptibility measurements. © 1995 The American Physical Society.
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Physical Review B, v. 51, n. 17, p. 11909-11914, 1995.