Colossal dielectric constant up to gigahertz at room temperature

The applicability of recently discovered materials with extremely high (“colossal”) dielectric constants, required for future electronics, suffers from the fact that their dielectric constant ε′ only is huge in a limited frequency range below about 1 MHz. In the present report, we show that the dielectric properties of a charge-ordered nickelate, La15/8Sr1/8NiO4, surpass those of other materials. Especially, ε′ retains its colossal magnitude of >10 000 well into the gigahertz range.