Solid state magnetic-dielectric bistability. Similar to the above-mentioned molecular bistability induced by the hidden PJTE, a magnetic-dielectric bistability due to two coexisting equilibrium configurations with corresponding properties may take place also in crystals with transition metal centers, subject to the electronic configuration with half-filled e or t shells. As in molecular systems, the latter produce a hidden PJTE and local bistability which, distinguished from the molecular case, are enhanced by the cooperative interactions, thus acquiring larger lifetimes. This crystal bistability was proved by calculations for LiCuO 2 and NaCuO 2 crystals, in which the Cu ion has the electronic e (d) configuration (similar to the CuF 3 molecule).