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arXiv · 0910.5585

Field-induced magnetism in the high-$T_c$ superconductor Ca$_{2-x}$Na$_x$CuO$_2$Cl$_2$ with flat CuO$_2$ planes

K. Ohishi·I. Yamada·A. Koda·S. R. Saha·R. Kadono·W. Higemoto·K. M. Kojima·M. Azuma·M. Takano
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Abstract

The internal magnetic field distribution in a mixed state of a cuprate superconductor, Ca$_{2-x}$Na$_x$CuO$_2$Cl$_2$ ($T_{\rm c}\simeq28.5$ K, near the optimal doping), was measured by muon spin rotation ($μ$SR) technique up to 60 kOe. The $μ$SR linewidth $Λ(B)$ which exhibits excess broadening at higher fields ($B>5$ kOe) due to field-induced magnetism (FIM), is described by a relation, $Λ(B)\propto\sqrt{B}$. This suggests that the orbital current and associated quasiparticle excitation plays predominant roles in stabilizing the quasistatic correlation. Moreover, a slowing down of the vortex fluctuation sets in well above $T_{\rm c}$, as inferred from the trace of FIM observed up to $\sim80$ K, and develops continuously without a singularity at $T_{\rm c}$ as the temperature decreases.

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K. Ohishi, I. Yamada, A. Koda, S. R. Saha, R. Kadono, W. Higemoto, K. M. Kojima, M. Azuma, M. Takano. 2009-10-29. Field-induced magnetism in the high-$T_c$ superconductor Ca$_{2-x}$Na$_x$CuO$_2$Cl$_2$ with flat CuO$_2$ planes. https://arxiv.org/abs/0910.5585

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