Unveiling excitonic insulator signatures in Ta[Formula: see text]NiSe[Formula: see text] through structural and orbital probes.

ABSTRACT: The high-temperature phase of Ta[Formula: see text]NiSe[Formula: see text], a near-zero-gap semiconductor ([Formula: see text] = 0), is a promising candidate for an excitonic insulator. Given the dome-like evolution expected for an excitonic insulator around [Formula: see text], we investigated Ta[Formula: see text]NiSe[Formula: see text], the more semi-metallic Ta[Formula: see text](Ni,Co)Se[Formula: see text], and semiconducting Ta[Formula: see text]NiS[Formula: see text] using high-resolution single-crystal x-ray diffraction and near-edge x-ray absorption fine structure (NEXAFS). Our findings reveal a second-order structural phase transition from orthorhombic (space group: Cmcm) to monoclinic (space group: C2/c) in Ta[Formula: see text]NiSe[Formula: see text] and Ta[Formula: see text](N

SUBMITTER: Maraytta N 

PROVIDER: S-EPMC12504696 | biostudies-literature | 2025 Oct

REPOSITORIES: biostudies-literature