Phase separation at the dimer-superconductor transition in Ir1−xRhxTe2

Abstract

The detailed evolution of the local atomic structure across the (x, T) phase diagram of transition metal dichalcogenide superconductor Ir1−xRhxTe2 (0≤x≤0.3, 10K≤T≤300K) is obtained from high-quality x-ray diffraction data using the atomic pair distribution function (PDF) method. The observed hysteretic thermal structural phase transition from a trigonal (P3¯m1) to a triclinic (P1¯) dimer phase for low Rh content emphasizes the intimate connection between the lattice and electronic properties. For superconducting samples away from the dimer/superconductor phase boundary, structural transition is absent and the local structure remains trigonal down to 10 K. In the narrow range of compositions close to the boundary, PDF analysis reveals structural phase separation, suggestive of weak first-order character of the Rh-doping induced dimer-superconductor quantum phase transition. Samples from this narrow range show weak anomalies in electronic transport and magnetization, hallmarks of the dimer phase, as well as superconductivity albeit with incomplete diamagnetic screening. The results suggest that the dimer and superconducting orders exist in the mutually exclusive spatial regions.

Source-reported materials — not catalogue approval

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