First-principles design of the spinel iridate Ir2O4 for high-temperature quantum spin ice

Insulating magnetic rare-earth pyrochlores related to spin ice host emergent bosonic monopolar spinons, which obey a magnetic analogue of quantum electrodynamics and may open a route to a magnetic analogue of electronics. However, the energy scales of the interactions among rare-earth moments are so low as 1 K that the possible quantum coherence can only be achieved at a sub-Kelvin. Here, we desgin high-temperature quantum spin ice materials from first principles. It is shown that the A-site deintercalated spinel iridate Ir2O4, which has been experimentally grown as epitaxial thin films, is a promising candidate for quantum spin ice with a spin-ice-rule interaction of a few tens of meV. Controlling electronic structures of Ir2O4 through substrates, it is possible to tune magnetic interactions so that a magnetic Coulomb liquid persists at high temperatures.