Electronic Structure of Charge Density Wave Transition in LaAgSb₂ Measured by Hard X-ray Photoemission Spectroscopy

Abstract

　We study the electronic structure of the charge density wave (CDW) transitions in LaAgSb₂, using bulk sensitive temperature dependent (20 K – 220 K) Hard X-ray photoemission spectroscopy (HAXPES). LaAgSb₂ exhibits two CDW transitions, one below T₁ = 207 K and a second CDW transition below T₂ = 186 K. Temperature dependent HAXPES core level measurements show that the La 3d and Ag 3d core-levels show negligible changes across the CDW transitions. In contrast, temperature dependent measurements of the Sb 3d core levels show a clear well-separated satellite below T₁, and the spectral intensity of the satellite progressively increases on lowering the temperature below T₂. The temperature dependence of the Sb 3d satellite feature suggests charge disproportionation, consistent with the CDW transition.