Ground-state phase diagram of dipolar-octupolar pyrochlores

摘要

The "dipolar-octupolar" pyrochlore oxides R_2M_2O_7 (R=Ce, Sm, Nd) represent an important opportunity in the search for three-dimensional quantum spin liquid (QSL) ground states. Their low-energy physics is governed by an alluringly simple "XYZ " Hamiltonian, enabling a theoretical description with only a small number of free parameters. Meanwhile, recent experiments on Ce pyrochlores strongly suggest QSL physics. Motivated by this, we present here a complete analysis of the ground-state phase diagram of dipolar-octupolar pyrochlores. Combining cluster mean-held theory, variational arguments, and exact diagonalization we find multiple U(1) QSL phases, which together occupy a large fraction of the parameter space. These results give a comprehensive picture of the ground-state physics of an important class of QSL candidates and support the possibility of a U(1) QSL ground state in Ce_2Zr_2O_7 and Ce_2Sn_2O_7.