title: Infrared evidence of a Slater metal-insulator transition in NaOsO₃.
abstract: The magnetically driven metal-insulator transition (MIT) was predicted by Slater in the fifties. Here a long-range antiferromagnetic (AF) order can open up a gap at the Brillouin electronic band boundary regardless of the Coulomb repulsion magnitude. However, while many low-dimensional organic conductors display evidence for an AF driven MIT, in three-dimensional (3D) systems the Slater MIT still remains elusive. We employ terahertz and infrared spectroscopy to investigate the MIT in the NaOsO₃ 3D antiferromagnet. From the optical conductivity analysis we find evidence for a continuous opening of the energy gap, whose temperature dependence can be well described in terms of a second order phase transition. The comparison between the experimental Drude spectral weight and the one calculated through Local Density Approximation (LDA) shows that electronic correlations play a limited role in the MIT. All the experimental evidence demonstrates that NaOsO₃ is the first known 3D Slater insulator.
authors.affiliation: Dipartimento di Fisica, Università di Roma "La Sapienza", Piazzale A. Moro 2, I-00185 Roma, Italy.
authors.forename: I Lo
authors.initials: IL
authors.lastname: Vecchio
authors.forename: A
authors.initials: A
authors.lastname: Perucchi
authors.forename: P
authors.initials: P
authors.lastname: Di Pietro
authors.forename: O
authors.initials: O
authors.lastname: Limaj
authors.forename: U
authors.initials: U
authors.lastname: Schade
authors.forename: Y
authors.initials: Y
authors.lastname: Sun
authors.forename: M
authors.initials: M
authors.lastname: Arai
authors.forename: K
authors.initials: K
authors.lastname: Yamaura
authors.forename: S
authors.initials: S
authors.lastname: Lupi