  Phase-change memory (PCM), a promising candidate for next-generation
non-volatile memories, exploits quenched glassy and thermodynamically stable
crystalline states as reversibly switchable state variables. We demonstrate PCM
functions emerging from a charge-configuration degree of freedom in strongly
correlated electron systems. Non-volatile reversible switching between a
high-resistivity charge-crystalline (or charge-ordered) state and a
low-resistivity quenched state, charge glass, is achieved experimentally via
heat pulses supplied by optical or electrical means in organic conductors
$\theta$-(BEDT-TTF)$_2$$X$. Switching that is one order of magnitude faster is
observed in another isostructural material that requires faster cooling to
kinetically avoid charge crystallization, indicating that the material's
critical cooling rate can be useful guidelines for pursuing a faster
correlated-electron PCM function.
