Magnetic Interactions in Cu(L-isoleucine)2.H2O: An EPR Measurement

D.M. MARTINO; M.C.G. PASSEGGI; R. CALVO

PHYSICAL REVIEW B - CONDENSED MATTER AND MATERIALS PHYSICS

Año: 1995 vol. 52 p. 9466 - 9476

0163-1829

Electron paramagnetic resonance (EPR) data have being obtained in single crystals of Cu(L-isoluecine)2 H2O at 9.7 and 33 GHz and at room temperature. This compound has four magnetically non-equivalent copper ions per unit cell, arranged in two symmetric-related type of layers, each involving two nonequivalent copper ions. The results are discussed in terms of both the classical stochastic Anderson theory of exchange narrowing and the Kubo and Tomita´theory. The exchange coupling JAF between magnetically nonequivalent copper ions in adjacent layers is estimated as JAF/k = 23(6) mK and JAF/k= 25(6) mK from the EPR line position and linewidth data respectively.Using the results on the angular variation of the linewidth we also evaluate the exchange coupling JF between magnetically nonequivalent neighbor copper ions within the same layer [JF/k = 140(3) mK]. Good agreement with values obtained previously from magnetic susceptibility data is found for these couplings parameters. This work emphasizes the suitability and simplicity of the EPR technique used in conjuction with the Anderson adn Kubo-Tomita theories, to evaluate small exchange interactions J/k < 200mK between magnetically nonequivalent ions in paramagnets, even in cases when stronger interactions might be present in the crystal.