Non-conventional superconducting fluctuations in Ba(Fe1-xRhx)(2)As-2 iron-based superconductors

Abstract

<p>We measured the static uniform spin susceptibility of Ba(Fe1−<em>x</em>Rh<em>x</em>)2As2 iron-based superconductors, over a broad range of doping (0.041 ≤ <em>x</em> ≤ 0.094) and magnetic fields. At small fields (<em>H</em> ≤ 1 kOe) we observed, above the transition temperature <em>T</em>c, the occurrence of precursor diamagnetism, which is not ascribable to the Ginzburg–Landau theory. On the contrary, our data agree with a phase fluctuation model, which has been used to interpret a similar phenomenology occurring in the high-<em>T</em>c cuprate superconductors. Additionally, in the presence of strong fields, the unconventional fluctuating diamagnetism is suppressed, whereas Ginzburg–Landau fluctuations are found, in agreement with literature.</p>