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arXiv 1805.04589cond-mat.supr-concond-mat.str-el
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Wiedemann-Franz定律与铜氧化物超导体赝能隙临界点电导率突变

Wiedemann-Franz law and abrupt change in conductivity across the pseudogap critical point of a cuprate superconductor

B. Michon, A. Ataei, P. Bourgeois-Hope, C. Collignon, S. Y. Li, S. Badoux, A. Gourgout, F. Laliberté, J. -S. Zhou, Nicolas Doiron-Leyraud, Louis Taillefer

备注：
10 pages, including Supplementary Material
发表信息：
Phys. Rev. X 8, 041010 (2018)
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摘要：

在七个掺杂从$p=0.12$到$p=0.24$的晶体中，在超导状态和磁场诱导正常状态下，测量了铜酸盐超导体La $_{1.6-x}$ Nd $_{0.4}$ Sr $_x$ CuO $_4$的热导率$κ$，低至50 mK。我们得到了电子剩余线性项$κ_0/T$作为$T \to 0$通过赝能隙临界点$p^{\star}= 0.23$。在正常状态下，我们观察到$κ_0/T$在低于$p^{\star}$时突然下降，这与载流子密度$n$从$1 + p$下降到$p$一致，这是从霍尔系数推断出的赝能隙相位的特征。在$H=0$观察到类似的$κ_0/T$下降，表明赝能隙临界点及其特征不受磁场影响。在正常状态下，在所有掺杂下都遵守Wiedemann-Franz定律，$κ_0/T=L_0/ρ(0)$，包括在电阻率$ρ(T)$为$T$ -线性下降到$T \to 0$的临界点。我们的结论是，在$T=0$的赝能隙相的非超导基态是一种金属，其费米激发进行常规电子的热量和电荷。

英文摘要：

The thermal conductivity $κ$ of the cuprate superconductor La$_{1.6-x}$Nd$_{0.4}$Sr$_x$CuO$_4$ was measured down to 50 mK in seven crystals with doping from $p=0.12$ to $p=0.24$, both in the superconducting state and in the magnetic field-induced normal state. We obtain the electronic residual linear term $κ_0/T$ as $T \to 0$ across the pseudogap critical point $p^{\star}= 0.23$. In the normal state, we observe an abrupt drop in $κ_0/T$ upon crossing below $p^{\star}$, consistent with a drop in carrier density $n$ from $1 + p$ to $p$, the signature of the pseudogap phase inferred from the Hall coefficient. A similar drop in $κ_0/T$ is observed at $H=0$, showing that the pseudogap critical point and its signatures are unaffected by the magnetic field. In the normal state, the Wiedemann-Franz law, $κ_0/T=L_0/ρ(0)$, is obeyed at all dopings, including at the critical point where the electrical resistivity $ρ(T)$ is $T$-linear down to $T \to 0$. We conclude that the non-superconducting ground state of the pseudogap phase at $T=0$ is a metal whose fermionic excitations carry heat and charge as conventional electrons do.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

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