6533b7ddfe1ef96bd1273d2e

RESEARCH PRODUCT

Pressure induced insulator/half-metal/metal transition in a strongly correlatedp-electron system

subject

description

Mixed-valent Rb${}_{4}$O${}_{6}$ provides an exceptional prototype material for studying the interplay between local correlations (Hubbard $U$) and electron kinetic energy ($W$) in the open $sp$-electron shell. Based on a first-principles calculation we show that depending on $U/W$ ratio, when tuned by external pressure, Rb${}_{4}$O${}_{6}$ exhibits a surprising sequence of phase transitions between strongly correlated antiferromagnetic insulator, ferromagnetic insulator ($U/W\phantom{\rule{-0.16em}{0ex}}\ensuremath{\gg}\phantom{\rule{-0.16em}{0ex}}1$), moderately correlated ferromagnetic half-metal ($U/W\phantom{\rule{-0.16em}{0ex}}\ensuremath{\sim}\phantom{\rule{-0.16em}{0ex}}1$), and finally itinerant nonmagnetic metal ($U/W\phantom{\rule{-0.16em}{0ex}}\ensuremath{\ll}\phantom{\rule{-0.16em}{0ex}}1$). This sequence, which is counterintuitive to the usual Bethe-Slater scenario, in addition exhibits the fully spin-polarized half-metallic ferromagnetic state revealed within the insulator-metal transition regime.