Electrical anisotropy and coexistence of structural transitions and superconductivity in IrT e2

We report experimental investigations of the electrical transport, magnetic, and thermodynamic properties of IrTe2 single crystals. The resistivity, magnetization, and specific heat display anomalies at TS1≈283K,TS2≈167K, and Tc≈2.5K, corresponding to two structural and one superconducting phase transitions, respectively, demonstrating the coexistence of all of these transitions in high-quality stoichiometric samples. While there is little magnetic anisotropy, a large ab-plane (ρab) and c-axis (ρc) electrical resistivity ratio (ρc/ρab≈730 at T=4K) is observed. This two-dimensional (2D) electronic character is further reflected in the disparate temperature dependences of ρab and ρc, with ρab exhibiting a Fermi-liquid-like T2 dependence below ∼25K, while ρc deviates significantly from this standard metallic behavior. In contrast, the magnetization is almost isotropic and negative over a wide temperature range. This can be explained by larger diamagnetism induced by electronic structure reconstruction as probed by the Hall effect and smaller positive contribution from itinerant electrons due to a low density of states (DOS) at the Fermi level. A small electronic specific heat coefficient with γ≈1.8mJ/molK2 confirms this assertion. This implies that IrTe2 is a weakly coupled superconductor. The connection between the superconductivity and the two structural transitions is discussed.