ESR study on YBiPt compound doped by Er3+ and Gd3+

Abstract

The compound YBiPt doped by Er and Gd has been studied by ESR technique in the X and Q-bands between 4 and 300 K. Two anisotropic lines with hyperfine peaks due to the interaction between electronic and nuclear spins of Er-167(3+) (I = 7/2) isotope have been observed below 30 K. Dysonian line shape of the Er and Gd ESR signals shows a metallic character of the conductivity in studied samples as well. Computer modeling has shown that these lines belong to the two allowed transitions in the quadruplet ground state of Er+3 ions in the ligand crystal field of cubic symmetry. The values of crystal field parameters B-4 = -5.68 x 10(-4) cm(-1) and B-6 = -6.64 x 10(-6) cm(-1) have been extracted. An additional isotropic line with g = 1.99 observed in both frequency bands has been attributed to the Gd impurities. The temperature dependence of peak-to-peak linewidth of Gd3+ signal has been well described by the Korringa relaxation of Gd magnetic moments to the itinerant electrons, dHpp = a + bT. The value of exchange constant J(sf) have been estimated from the Korringa slope of b = 0.12 Oe/K. The intensity of Gd3+ signal, which obeys the Curie's law for paramagnetic ions at lowest temperatures, deviates from this law at temperatures higher than 140 K. (C) 2002 Elsevier Science B.V. All rights reserved.