Modeling Yb₂Be₂GeO₇ on a Shastry Sutherland Lattice to Investigate Broad Spectral Features

Yb₂Be₂GeO₇ is a magnetic Mott insulator with a 2D Shastry Sutherland Lattice (SSL) of Yb³⁺ (S=1/2) ions. This material shows no ordering down to 300mK and is a potential quantum spin liquid candidate. Inelastic neutron scattering (INS) has revealed a low energy spectrum with broad features possibly indicating fractionalization of magnons. Further, a narrow non-dispersive band of excitations is found to rise linearly in an applied magnetic field. In order to address these puzzles, we fit thermodynamic data to determine the exchange interactions to model the system using exact diagonalization. Magnetization, susceptibility, and heat capacity are used to find both the magnitude and sign of Heisenberg and Ising interactions on the nearest neighbor and diagonal bonds. We calculate the dynamical structure factor and compare with the INS low energy spectrum.