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arXiv · 1310.4080

Coexistence of cluster spin glass and superconductivity in Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ for $0.060 \leq x \leq 0.071$

A. P. Dioguardi·J. Crocker·A. C. Shockley·C. H. Lin·K. R. Shirer·D. M. Nisson·M. Lawson·N. apRoberts-Warren·P. C. Canfield·S. L. Bud'ko·S. Ran·N. J. Curro
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Abstract

We present 75As nuclear magnetic resonance data from measurements of a series of Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ crystals with $0.00 \leq x \leq 0.075$ that reveals the coexistence of frozen antiferromagnetic domains and superconductivity for $0.060 \leq x \leq 0.071$. Although bulk probes reveal no long range antiferromagnetic order beyond $x = 0.06$, we find that the local spin dynamics reveal no qualitative change across this transition. The characteristic domain sizes vary by more than an order of magnitude, reaching a maximum variation at $x = 0.06$. This inhomogeneous glassy dynamics may be an intrinsic response to the competition between superconductivity and antiferromagnetism in this system.

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A. P. Dioguardi, J. Crocker, A. C. Shockley, C. H. Lin, K. R. Shirer, D. M. Nisson, M. Lawson, N. apRoberts-Warren, P. C. Canfield, S. L. Bud'ko, S. Ran, N. J. Curro. 2013-10-15. Coexistence of cluster spin glass and superconductivity in Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ for $0.060 \leq x \leq 0.071$. https://doi.org/10.1103/physrevlett.111.207201

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