Bulk antiferromagnetism in $\mathbf{N}{\mathbf{a}}_{0.82}\mathbf{Co}{\mathbf{O}}_2$ single crystals

Abstract

Susceptibility, specific heat, and muon spin rotation measurements on high-quality single crystals of $\mathrm{N}{\mathrm{a}}_{0.82}\mathrm{Co}{\mathrm{O}}_2$ have revealed bulk antiferromagnetism with Néel temperature ${\mathrm{T}}_{\mathrm{N}}=19.8\pm 0.1$ K and an ordered moment perpendicular to the $\mathrm{Co}{\mathrm{O}}_2$ layers. The magnetic order encompasses nearly 100% of the crystal volume. The susceptibility exhibits a broad peak around 30 K, characteristic of two-dimensional antiferromagnetic fluctuations. The in-plane resistivity is metallic at high temperatures and exhibits a minimum at ${\mathrm{T}}_{\mathrm{N}}$.

published version