Ground state phase diagram of dipolar-octupolar pyrochlores

Abstract

The dipolar-octupolar pyrochlore oxides R$_2$M$_2$O$_7$ (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 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 field 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$_2$Zr$_2$O$_7$ and Ce$_2$Sn$_2$O$_7$