Anomalous local magnetic field distribution and strong pinning in CaFe1.94Co0.06As2 single crystals
1 Department of Physics, Indian Institute of Technology - Kanpur-208016, India
2 Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research - Mumbai 400005, India
Received: 11 October 2012
Accepted: 1 November 2012
Magneto-optical imaging of a single crystal of CaFe1.94Co0.06As2, shows anomalous remnant magnetization within Meissner-like regions of the superconductor. The unconventional shape of the local magnetization hysteresis loop suggests admixture of superconducting and magnetic fractions governing the response. Near the superconducting transition temperature the local magnetic field exceeds the applied field resulting in a diamagnetic to positive magnetization transformation. The observed anomalies in the local magnetic field distribution are accompanied with enhanced bulk pinning in the CaFe1.94Co0.06As2 single crystals. We propose that our results suggest a coexistence of superconductivity and magnetic correlations.
PACS: 74.25.Ha – Magnetic properties including vortex structures and related phenomena / 74.70.Xa – Pnictides and chalcogenides / 75.40.-s – Critical-point effects, specific heats, short-range order
© EPLA, 2012