Low temperature vortex liquid in $\rm La_{2-x}Sr_xCuO_4$

Lu Li; J. G. Checkelsky; Seiki Komiya; Yoichi Ando; N. P. Ong

doi:10.1038/nphys563

paper

Low temperature vortex liquid in $L a_{2 - x} S r_{x} Cu O_{4}$

arXiv:cond-mat/0702121 · doi:10.1038/nphys563

Abstract

In the cuprates, the lightly-doped region is of major interest because superconductivity, antiferromagnetism, and the pseudogap state \cite{Timusk,Lee,Anderson} come together near a critical doping value $x_{c}$ . These states are deeply influenced by phase fluctuations \cite{Emery} which lead to a vortex-liquid state that surrounds the superconducting region \cite{WangPRB01,WangPRB06}. However, many questions \cite{Doniach,Fisher,FisherLee,Tesanovic,Sachdev} related to the nature of the transition and vortex-liquid state at very low tempera- tures $T$ remain open because the diamagnetic signal is difficult to resolve in this region. Here, we report torque magnetometry results on $L a_{2 - x} S r_{x} Cu O_{4}$ (LSCO) which show that superconductivity is lost at $x_{c}$ by quantum phase fluctuations. We find that, in a magnetic field $H$ , the vortex solid-to-liquid transition occurs at field $H_{m}$ much lower than the depairing field $H_{c 2}$ . The vortex liquid exists in the large field interval $H_{m} ≪ H_{c 2}$ , even in the limit $T \to$ 0. The resulting phase diagram reveals the large fraction of the $x$ - $H$ plane occupied by the quantum vortex liquid.

6 pages, 4 figures, submitted to Nature Physics

Low temperature vortex liquid in La2−x​Srx​CuO4​

Abstract

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Low temperature vortex liquid in $L a_{2 - x} S r_{x} Cu O_{4}$