Magnetic properties of crystalline random anisotropy Tb sub x Y sub 1 minus sub x Al sub 2 magnets

The magnetic phase diagram of the crystalline dilute magnets Tb{sub {ital x}}Y{sub 1{minus}{ital x}}Al{sub 2} has been determined, showing spin-glass reentrance into a quasiferromagnetic (QF) phase for {ital x}{sub {ital t}} {ge} 0.27 and {ital T} {le} 8.6 K, the tricritical point. The effective percolation limit is {ital x}{sub {ital p}}=0.16 with a critical line separating the paramagnetic and QF regimes of exponent {phi}{sub {ital p}}=1.1. No signs of saturation magnetization are found, nor of any clear divergence of the dc zero-field susceptibility. On the spin-glass side of these series ({ital x}{lt}0.27), the order parameters {ital q} (frozen local moment) and {Delta} (irreversibility parameter) have been determined from the field- and zero-field-cooled measured susceptibilities.