UC Irvine

The Eu2+ (4 f7, S=72) g value in Ca1-x Eux B6 (0.15≲x≤1.00) was measured by means of electron spin resonance at two frequencies (fields), 9.4 (≈3.4 kOe) and 34.4 GHz (≈12.1 kOe). The g value was found to be anisotropic and magnetic-field dependent. The amplitude of the anisotropy increases at low temperatures. The observed angular and temperature dependences of the g value suggest tetragonal symmetry caused, presumably, by a distortion along a direction perpendicular to the largest crystal face, the [001] direction. Due to the platelet shape of the samples, part of the anisotropy of the g value can also be attributed to demagnetization effects. The g values decrease at higher fields, which is interpreted in terms of a two-band model involving an exchange interaction between the localized Eu2+ 4 f7 electrons with conduction Eu2+ 5d -like electrons and B 2p -like holes. © 2006 American Institute of Physics.