Spin Ordering in LaOFeAs and Its Suppression in Superconductor LaO0.89F0.11FeAs Probed by Mössbauer Spectroscopy - Condensed Matter > Superconductivity

Spin Ordering in LaOFeAs and Its Suppression in Superconductor LaO0.89F0.11FeAs Probed by Mössbauer Spectroscopy - Condensed Matter > Superconductivity - Download this document for free, or read online. Document in PDF available to download.

Abstract: The 57Fe M\-ossbauer spectroscopy was applied to an iron-based layeredsuperconductor LaO0.89F0.11FeAs with a transition temperature of 26 K and itsparent material LaOFeAs. Throughout the temperature range from 4.2 to 298 K, asinglet spectrum with no magnetic splitting was observed as a main component ofeach M\-ossbauer spectrum of the F-doped superconductor. No additional internalmagnetic field was observed for the spectrum measured at 4.2 K under a magneticfield of 7 T. On the other hand, the parent LaOFeAs shows a magnetic transitionat around 140 K, and this temperature is slightly lower than that of astructural phase transition from tetragonal to orthorhombic phase, whichaccompanies the resistivity anomaly at around 150 K. The magnetic moment isestimated to be ~0.35 $\mu$B-Fe at 4.2 K in the orthorhombic phase, and thespin disorder remains in the magnetic ordered state even at 4.2 K. The factthat no magnetic transition in LaO0.89F0.11FeAs was observed even at 4.2 Kunder 7 T implies a strong spin fluctuation above Tc or small magnetic momentin this system. Therefore, the present results show that the F-dopingeffectively suppresses the magnetic and structural transitions in the parentmaterial and the suppression leads to emergence of superconductivity in thissystem.

Author: S. Kitao, Y. Kobayashi, S. Higashitaniguchi, M. Saito, Y. Kamihara, M. Hirano, T. Mitsui, H. Hosono, M. Seto

Source: https://arxiv.org/