PhD Position : Superconductivity and charge-density waves in Kagome Lattices

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Testo originale dell'annuncio (in inglese)

General Scope: The kagome lattice (see Fig. 1A) has long attracted attention to the quantum materials community. Originally, the focus was on insulating frustrated magnets in the search for a quantum spin liquid state. More recently, metallic kagome systems are the focus of a growing community, boosted by the discovery of superconductivity in the AV3Sb5 family (A=K, Rb, Cs) [1]. The rich electronic band structure of Kagome metals includes van Hove singularities (VHS), flat bands, and Dirac cones that can promote instabilities beyond superconductivity such as charge- density waves (CDW). External tuning of the band structure can strongly modify the electronic properties, e.g., by reaching van Hove filling where the electronic density of states is singular. PhD Subject: This PhD project proposes to investigate Kagome metals under uniaxial stress (see Fig. 1) with the aim to understand and take advantage of the interplay between physical properties and the electronic band structure. In this context, the PhD student will perform experiments under uniaxial stress, in particular electrical transport and calorimetry measurements to gain symmetry- resolved information on the electronic fluctuations at the Fermi level and the density of states. Two systems will be investigated where VHS is close to the Fermi energy. First, the AM6X6 family (e.g., ScV6Sn6) that includes more than 125 compounds chemically stable [2] and where the aim will be to understand the origin of the stress-sensitive ‘rattling’-type CDW observed in a few materials. Second, we will investigate the superconducting AV3Sb5 family, where the aim will be to deeply understand the relationship between superconductivity and the CDW of the material [3]. [1] Ortiz et al., PRL 125, 247002 [2] Ortiz et al., JACS 147, 5279-5292 (2025) [3] Frachet et al., PRL 132, 186001 (2024) Required Skills: • Strong background in condensed matter physics. • Previous experience in experimental physics (cryogenic, instrumentation, …). • Self-motivation and perseverance to perform demanding experiments. • Excellent communication skills.