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arXiv · 1103.0146

Pseudogap-like phase in Ca(Fe$_{1-x}$Co$_x$)$_2$As$_2$ revealed by $^{75}$As NQR

S. -H. Baek·H. -J. Grafe·L. Harnagea·S. Singh·S. Wurmehl·B. Büchner
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Abstract

We report $^{75}$As NQR measurements on single crystalline Ca(Fe$_{1-x}$Co$_x$)$_2$As$_2$ ($0\leq x \leq 0.09$). The nuclear spin-lattice relaxation rate $T_1^{-1}$ as a function of temperature $T$ and Co dopant concentration $x$ reveals a normal-state pseudogap-like phase below a crossover temperature $T^*$ in the under- and optimally-doped region. The resulting $x$-$T$ phase diagram shows that, after suppression of the spin-density-wave order, $T^*$ intersects $T_c$ falling to zero rapidly near the optimal doping regime. Possible origins of the pseudogap behavior are discussed.

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S. -H. Baek, H. -J. Grafe, L. Harnagea, S. Singh, S. Wurmehl, B. Büchner. 2011-09-14. Pseudogap-like phase in Ca(Fe$_{1-x}$Co$_x$)$_2$As$_2$ revealed by $^{75}$As NQR. https://doi.org/10.1103/physrevb.84.094510

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