Magnetization, electrical resistivity and specific heat measurements of Na Co2O4

Abstract DC magnetic susceptibility (χ), electrical resistivity (ρ) and specific heat (C) have been investigated for layered compound NaxCo2O4 as a function of temperature (T) using high purity specimens melted and grown in a floating-zone furnace. A broad maximum of χ(T) at ∼14 K , a behavior of ρ(T) obeying ρ(T)=ρ0+AT2 at low temperatures and a large γ (=C/T) value of ∼60 mJ / mol K 2 at 2 K are found. These behaviors are qualitatively similar to those of a d-electron heavy fermion compound LiV2O4.