1107.0904 (H. Xiao et al.)

Evidence for filamentary superconductivity nucleated at antiphase domain
walls in antiferromagnetic CaFe$_2$As$_2$    [PDF]

H. Xiao, T. Hu, A. P. Dioguardi, N. apRoberts-Warren, A. C. Shockley, J. Crocker, D. M. Nisson, Z. Viskadourakis, Xianyang Tee, I. Radulov, C. C. Almasan, N. J. Curro, C. Panagopoulos

Resistivity, magnetization and microscopic $^{75}$As nuclear magnetic
resonance (NMR) measurements in the antiferromagnetically ordered state of the
iron-based superconductor parent material CaFe$_2$As$_2$ exhibit anomalous
features that are consistent with the collective freezing of domain walls.
Below $T^*\approx 10$ K, the resistivity exhibits a peak and downturn, the bulk
magnetization exhibits a sharp increase, and $^{75}$As NMR measurements reveal
the presence of slow fluctuations of the hyperfine field. These features in
both the charge and spin response are strongly field dependent, are fully
suppressed by $H^*\approx 15$ T, and suggest the presence of filamentary
superconductivity nucleated at the antiphase domain walls in this material.

View original: http://arxiv.org/abs/1107.0904