Observation of Unprecedented Fractional Magnetization Plateaus in a New Shastry-Sutherland Ising Compound

Abstract

Geometrically frustrated magnetic systems, such as those based on the Shastry-Sutherland lattice (SSL), offer a rich playground for exploring unconventional magnetic states. The delicate balance between competing interactions in these systems leads to the emergence of novel phases. We present the characterization of Er2Be2GeO7, an SSL compound with Er3+ ions forming orthogonal dimers separated by non-magnetic layers whose structure is invariant under the P-421m space group. Neutron scattering reveals an antiferromagnetic dimer structure at zero field, typical of Ising spins on that lattice and consistent with the anisotropic magnetization observed. However, magnetization measurements exhibit fractional plateaus at 1/4 and 1/2 of saturation, in contrast to the expected 1/3 plateau of the SSL Ising model. By comparing the energy of candidate states with ground-state lower bounds we show that this behavior requires spatially anisotropic interactions, leading to an anisotropic Shastry-Sutherland Ising Model (ASSLIM) symmetric under the Cmm2 space group. This anisotropy is consistent with the small orthorhombic distortion observed with single-crystal neutron diffraction. The other properties, including thermodynamics, which have been investigated theoretically using tensor networks, point to small residual interactions, potentially due to further couplings and quantum fluctuations. This study highlights Er2Be2GeO7 as a promising platform for investigating exotic magnetic phenomena.

Accepted for publication in Physical Review X

References in corpus (9)

• A quantum magnetic analogue to the critical point of water
• PyCrystalField: Software for Calculation, Analysis, and Fitting of Crystal Electric Field Hamiltonians
• Incomplete devil's staircase in the magnetization curve of SrCu2(BO3)2
• Magnetic properties of the Shastry-Sutherland lattice material BaNd${}_2$ZnO${}_5$
• Solving frustrated Ising models using tensor networks
• Field-Induced Partial Disorder in a Shastry-Sutherland Lattice
• A Candidate for the Quantum Spin Liquid Ground-State in the Shastry-Sutherland Lattice Material Yb${}_2$Be${}_2$GeO${}_7$
• Systematic Analysis of Crystalline Phases in Bosonic Lattice Models with Algebraically Decaying Density-Density Interactions
• Quantum phases of hardcore bosons with repulsive dipolar density-density interactions on two-dimensional lattices

Cited by in corpus (1)

• Zeta expansion for long-range interactions under periodic boundary conditions with applications to micromagnetics