Anomalous remnant magnetization in dilute antiferromagnetic Gd1-x Yx B4

Magnetic properties of dilute single crystals of Gd1-xYxB4 (x=0, 0.2, and 0.4) were systematically studied. These antiferromagnetic Shastry-Sutherland compounds display a remnant magnetization MR when field cooled below the Néel temperature TN. The magnitude of MR at low magnetic fields is magnetic field dependent, increasing with increasing magnetic fields, and it saturates for H≤30 Oe. The MR(T) data for both x=0.2 and 0.4 compositions overlap, and the remnant magnetization follows a universal behavior. We argue that these findings are explained by taking into account the formation of magnetic domains within the crystals, originating from the dilution of a magnetically frustrated, antiferromagnetic sublattice.