Hyperfine effects and electron spin relaxation of 51V4+ doped into scandium orthosilicate Sc228SiO5: CW and pulsed X-band electron spin resonance studies

The scandium orthosilicate monocrystal (Sc2SiO5)-Si-28 (SSO) doped with V-51 isotope in small concentrations (0.005% at.) was studied. We used continuous wave (CW) and pulsed electron spin resonance (ESR) methods with frequencies in the X-band range (9.3-9.8 GHz). From the orientational dependencies of the CW ESR spectra we found the following: the hyperfine interaction of the vanadium ions is very anisotropic and the Zeeman interaction is almost isotropic with principal values of the g - tensor near electron g - factor. In addition to that, we found that the charge state of vanadium ions is V4+. The directions of the principal axes of the A and g tensors were determined. The phase memory and spin-lattice relaxation were measured. It was found that the temperature dependence of the spin-lattice relaxation time can be approximated by the sum of direct and Aminov-Orbach processes with decent accuracy. The phase memory time stays in the microseconds range even at the temperature T = 30 K.