Ground-state phase diagram of dipolar-octupolar pyrochlores
Owen Benton
Abstract
The ``dipolar-octupolar'' pyrochlore oxides ${\mathrm{R}}_{2}{\mathrm{M}}_{2}{\mathrm{O}}_{7}$ (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 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-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 ${\mathrm{Ce}}_{2}{\mathrm{Zr}}_{2}{\mathrm{O}}_{7}$ and ${\mathrm{Ce}}_{2}{\mathrm{Sn}}_{2}{\mathrm{O}}_{7}$.