Disorder-driven electronic localization and phase separation in superconducting Fe1+yTe0.5Se0.5 single crystals

Roessler, S and Cherian, Dona and Harikrishnan, S and Bhat, HL and Elizabeth, Suja and Mydosh, JA and Tjeng, LH and Steglich, F and Wirth, S (2010) Disorder-driven electronic localization and phase separation in superconducting Fe1+yTe0.5Se0.5 single crystals. In: Physical Review B: Condensed Matter and Materials Physics, 82 (14).

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Abstract

We have investigated the influence of Fe excess on the electrical transport and magnetism of Fe1+yTe0.5Se0.5 (y=0.04 and 0.09) single crystals. Both compositions exhibit resistively determined superconducting transitions (T-c) with an onset temperature of about 15 K. From the width of the superconducting transition and the magnitude of the lower critical field H-c1, it is inferred that excess of Fe suppresses superconductivity. The linear and nonlinear responses of the ac susceptibility show that the superconducting state for these compositions is inhomogeneous. A possible origin of this phase separation is a magnetic coupling between Fe excess occupying interstitial sites in the chalcogen planes and those in the Fe-square lattice. The temperature derivative of the resistivity d(rho)/d(T) in the temperature range T-c < T < T-a with T-a being the temperature of a magnetic anomaly, changes from positive to negative with increasing Fe. A log 1/T divergence of the resistivity above T-c in the sample with higher amount of Fe suggests a disorder-driven electronic localization.

Item Type:	Journal Article
Publication:	Physical Review B: Condensed Matter and Materials Physics
Publisher:	The American Physical Society
Additional Information:	Copyright of this article belongs to The American Physical Society.
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	11 Nov 2010 10:51
Last Modified:	11 Nov 2010 10:51
URI:	http://eprints.iisc.ac.in/id/eprint/33647

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