Phase Diagram of a Spin-ice Kondo Lattice Model in a Breathing Pyrochlore Lattice

We study a spin-ice Kondo lattice model on a breathing pyrochlore lattice with classical localized spins. The highly efficient kernel polynomial expansion method, together with a classical Monte Carlo method, is employed in order to study the magnetic phase diagram at four representative values of the number density of itinerant electrons. We tune the breathing mode by varying the hopping ratio -- the ratio of hopping parameters for itinerant electrons along inequivalent paths. Several interesting magnetic phases are stabilized in the phase diagram parameterized by the hopping ratio, Kondo coupling, and electronic filling fraction, including an "all-in/all-out" ordered spin configuration phase, spin-ice, ordered phases containing $16$ and $32$ spin sites in the magnetic unit cell, as well as a disordered phase at small values of the hopping ratio.