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Seminar MCBT : Monday, 20th March at 14:00


Mehdi Frachet (Institute for Quantum Materials and Technologies, Karlsruhe Institute of Technology)


Title : Investigating electronic phases of quantum materials using the host crystal lattice


Institut Néel, Room D420 (Nevill Mott)
Abstract : Within the vast diversity of collective electronic behaviours found in quantum materials, often the host crystal lattice plays a significant role. Consequently, manipulating or probing the crystal lattice gives insightful information on the electronic ordering tendencies of quantum matter.
In this talk, I will highlight the relevance of several (complementary) strain-based approaches for the study of quantum materials. First, we will discuss ultrasound measurements that give insight on the coupling of electronic instabilities to lattice strain. This case will be illustrated with high magnetic fields ultrasound measurements of the high-Tc superconductor La2-xSrxCuO4. Ultrasound measurements allow to study the glassy magnetism of the compound [1], together with its connections to the mysterious pseudogap phase and the signatures of quantum criticality [2]. Second, anisotropic strain can be applied as a tuning parameter, acting as a conjugate field for nematic orders. Here, I will focus on recent elastoresistance measurements in the superconductor BaNi2(As1-xPx)2 [3], a candidate system for charge-driven electronic nematicity that is structurally analogous to iron-based superconductors [4-6]. The origin of the sharp (B1g-symmetric) elastoresistance response and its relation to the superconducting and charge-ordered phases will be discussed. Finally, I will mention exciting new directions in the strain-tuning of quantum materials and promising systems to investigate.
[1] Frachet et al., Phys. Rev. B 103, 115133 (2021)
[2] Frachet*, Vinograd* et al., Nat Phys. 16, 1064-1068 (2020)
[3] Frachet et al., npj Quantum Mater. 7, 115 (2022)
[4] Merz et al., Phys. Rev. B 104, 184509 (2021)
[5] Eckberg et al., Nat. Phys. 16, 346-350 (2020)
[6] Yao et al., Nat. Comm. 13, 4535 (2022)