Interplay between Superconductivity and Magnetism in FeSe under pressure and FeSe1-xSx via TDO

Author: Abedin, Rafee

Affiliation: University of Oxford

Type: Poster

Display Dates: 22.07.2026 - 23.07.2026

Board: WT-034

The exotic high-Tc superconductivity of iron chalcogenides is postulated to be mediated by magnetic or nematic fluctuations 1-3. However, signatures of magnetic order are difficult to detect in the bulk FeSe family due to different competing magnetic interactions, and an SDW phase is only stabilized under applied pressure 2-4. The tunnel diode oscillator (TDO) technique is a powerful inductive measurement viable in extreme conditions to detect changes in the electronic, magnetic and superconducting properties via the skin depth and penetration depth. We report a detailed TDO study of FeSe under pressures of up to 5 GPa in magnetic fields up to 16T and at ambient pressure for FeSe1-xSx, up to 80 T 5. We identify clear signatures of magnetic and superconducting orders across the T-B phase diagrams. The nature of magnetic anomalies in TDO changes significantly as a function of applied pressure due to coupling with the nematic phase and coexistence with superconductivity. Additionally, we detect quantum oscillation consistent with Fermi surface reconstruction and clear field-induced anomalies which suggest the stabilization of an incipient SDW inside the nematic phase of FeSe1-xSx. We assess the pressure evolution of the gap structure in FeSe via penetration depth. Our study reveals the sensitivity of the interplay between superconductivity and magnetism of iron chalcogenides.

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[5] I. Paulescu, et al (in preparation)