A Nuclear Orientation Study of Terbium Ethyl Sulphate

Abstract

Terbium ethyl suphate (TbES) has been studied by nuclear orientation using radioactive 160Tb. It is found that (i) it is difficult to cool the terbium nuclei below ~50 mK because of the long nuclear spin-lattice relaxation time TIN; (ii) application of small magnetic fields of the order 0·1 T produces a dramatic increase in the value of TIN; the long electronic relaxation time T1E makes it difficult to determine the Curie temperature Tc in such experiments; and (iv) the saturation magnetic moment is approximately 7·35I'B. No nuclear magnetic resonance transitions were detected when radio-frequency fields at frequencies from 190 to 920 MHz were applied, but a long series of resonance absorption peaks was observed with a frequency separation of 26·3(3) MHz. Their origin ascribed to magneto-acoustic modes within magnetic domains, rather than to magnetostatic modes, magnetic spin waves, or resonances within domain walls.