Speaker
Dr
Alessandro Puri
(High Field Magnet Laboratory, Institute of Molecules and Materials, Radboud University Nijmegen, Toernooiveld 7, 6525 ED Nijmegen, Netherlands)
Description
The discovery of FeSexTe1−x compounds belonging to the (11) family of iron chalcogenides attracted the attention of both theoreticians and experimentalists because of their simple crystal structure and a rich phase diagram where magnetic and superconducting phases may coexist forming two networks at the nanoscale.
Thanks to the high values of the upper critical field and to the critical current density FeSexTe1−x compounds are ideal candidates for many technological applications. However, the lack of understanding regarding the correlation dynamics between the flux lines in the mixed state represents a real bottleneck. The main obstacle for reliable technological applications is the reduction of the dissipative phenomena due to the magnetic vortex motion inside the material. In this contribution we present alternated current (ac) multi-harmonic susceptibility measurements and the irreversibility line analysis on FeSe0.25Te0.75. The ac susceptibility is indeed a powerful technique for this kind of analysis, because it directly probes the dynamic magnetization of the material. In particular the high harmonic coefficients (χn) probe the irreversible flux-pinning response of superconducting phases occurring in the compound.
The extremely high magnetic fields (up to 33 T) available at the HFML laboratory in Nijmegen, gave us the opportunity to map a wide frequency-field-temperature region of the FeSe0.25Te0.75 phase diagram. We have accurately characterized the irreversible region up to 15 T and we have estimated Hc2(0K) ~30 T. Data help to clarify the complex relationship between the magnetic vortex lines and the superconductive phase.
Author
Dr
Alessandro Puri
(High Field Magnet Laboratory, Institute of Molecules and Materials, Radboud University Nijmegen, Toernooiveld 7, 6525 ED Nijmegen, Netherlands)
Co-authors
Dr
Alessandro Ricci
(Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, D-22607 Hamburg, Germany)
Augusto Marcelli
(INFN/LNF)
Dr
Daniele Di Gioacchino
(INFN-Laboratori Nazionali di Frascati, Via E. Fermi 40, 00044 Frascati (RM), Italy)
Dr
Nicola Poccia
(MESA+ Institute for Nanotechnology, University of Twente, P. O. Box 217, 7500AE Enschede, Netherlands)
Uli Zeitler
(High Field Magnet Laboratory, Institute of Molecules and Materials, Radboud University Nijmegen, Toernooiveld 7, 6525 ED Nijmegen, Netherlands)
