Fractional magnetization plateaus in theShastry-Sutherland lattice material Er2Be2GeO7

The experimental study of magnetism on the Shastry-Sutherland lattice has been ongoing for more than two decades, following the discovery of the first Shastry- Sutherland lattice material SrCu2(BO3)2. However, investigation of Shastry- Sutherland lattice systems is often complicated by the requirements of high magnetic fields (e.g., > 20 T for SrCu2(BO3)2) or the presence of itinerant electrons (e.g., REB4). In this paper, we present the magnetic properties of the Shastry-Sutherland lattice material Er2Be2GeO7. Like SrCu2(BO3)2, Er2Be2GeO7 exhibits fractional magnetization plateaus. However, unlike SrCu2(BO3)2, Er2Be2GeO7 exhibits long- range order below ∼ 1 K, and the plateaus are accessible using commercial laboratory equipment, occurring for fields < 1 T. The fractions of magnetization present are closest to 1/4, 4/9, and 1/2 of the saturation magnetization. Hysteresis is observed in the 4/9 and 1/2 plateau phases. The lack of itinerant electrons, chemical disorder, and the low fields required to access the fractional magnetization plateaus shows Er2Be2GeO7 holds promise as a prime candidate for the study of frustrated magnetism on the Shastry-Sutherland lattice.