Analysis of quadrupolar spin echoes in a series of V3X compounds

In a series of vanadium based A 15 intermetallic compounds, the nuclear spin-echo patterns of vanadium $\text{(I=}\text{7}\text{2}\text{)}$ were recorded and analysed. The spin system was inhomogeneously broadened by magnetic as well as quadrupolar interactions, which resulted in the observation of “allowed” (Δm′ = 1) and “forbidden” (Δm′ > 1) echos. A comparison was made between the c.w. line shapes and the spin-echo patterns. Higher-order echoes at t = 4τ (Δm′ = 3) and t = 6τ (Δm′ = 5) were observed in V₃Au and V₃Co. An analysis of higher-order quadrupolar spin echoes is given, based on the theory in which the quadrupolar interaction during the pulses is taken into account.