28 August 2022 to 2 September 2022
Science and Technology Campus, University of Parma
Europe/Rome timezone
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Anomalous behaviour of the mixed phase of superconducting LaFeAsO$_{1-x}$F$_{x}$

P-THU-35
1 Sept 2022, 17:20
1h 40m
Science and Technology Campus, University of Parma

Science and Technology Campus, University of Parma

University of Parma, Italy
Poster Superconductivity Posters

Speaker

Dr Giacomo Prando (Dipartimento di Fisica, Università degli Studi di Pavia, Italia)

Description

The Fe-based superconductors have been extensively investigated in view of the intimate interplay of the magnetic and superconducting phases developing therein. Here, we show an anomalous behaviour of the mixed phase in the family of superconducting compounds LaFeAsO$_{1-x}$F$_{x}$ as detected by transverse-field muon spin rotation. This technique is the best tool to probe both the flux line lattice distribution and any additional source of magnetism through both the muon depolarization rate and the local magnetic field at the muon site $B_{\mu}$. Although the typical shielding behaviour is expected to saturate to a constant value well below the superconducting transition $T_{c}$, our results for LaFeAsO$_{1-x}$F$_{x}$ show that $B_{\mu}$ is enhanced in the low-temperature regime (see figure). We discuss an extensive investigation of this phenomenon as a function of F doping, external magnetic field and temperature alongside different interpretations for the observed phenomenology, including a spontaneous magnetic re-entrance and a possible change of the flux line lattice distribution [1].

Temperature dependence of the internal magnetic field at the muon site for LaFeAsO$_{1-x}$F$_{x}$ ($x = 0.1$) field cooled in a transverse external field $B_{ext} \simeq 600$ G. An anomalous enhancement is observed in the low temperature regime.

[1] Manuscript in preparation (2022).

Primary author

Dr Giacomo Prando (Dipartimento di Fisica, Università degli Studi di Pavia, Italia)

Co-authors

Mr Matteo Casadei (Dipartimento di Fisica e Astronomia "Augusto Righi", Università di Bologna, Italia) Dr Gianrico Lamura (CNR-SPIN, Italia) Prof. Pietro Carretta (Dipartimento di Fisica, Università degli Studi di Pavia, Italia) Prof. Samuele Sanna (Dipartimento di Fisica e Astronomia "Augusto Righi", Università di Bologna, Italia)

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