A ferroelectric quantum phase transition inside the superconducting dome of Sr1-xCaxTiO3-δ
A ferroelectric quantum phase transition inside the superconducting dome of Sr1-xCaxTiO3-δ
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DOI：
10.1038/nphys4085
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发表时间：
2017-07-01
期刊：
影响因子：
19.6
通讯作者：
Behnia, Kamran
中科院分区：
文献类型：
--
作者：
Rischau, Carl Willem;Lin, Xiao;Behnia, Kamran
SrTiO 3是量子顺电体（1），在除去极少量的氧原子（2）后成为具有超导不稳定性的金属。它变成一个铁电体后，一小部分的锶原子取代钙（3）。这两个顺序可能是偶然的邻居或密切相关，如量子临界铁电性的图片（4）。在这里，我们表明，在Sr_（1-x）Ca_xTiO_（3-δ）（0.002 < x < 0.009，δ < 0.001）的铁电有序共存稀金属和超导不稳定性在一个有限的窗口的掺杂。在临界载流子密度，这与钙含量的比例，量子相变破坏铁电秩序。我们检测到正常状态的散射和一个显着的修改超导圆顶附近的量子相变的好转。用钙取代的超导转变温度的提高证明了铁电邻近在该系统中超导性的早熟出现中所起的作用，限制了配对的可能的理论方案。
SrTiO3, a quantum paraelectric(1), becomes a metal with a super-conducting instability after removal of an extremely small number of oxygen atoms(2). It turns into a ferroelectric upon substitution of a tiny fraction of strontium atomswith calcium(3). The two orders may be accidental neighbours or intimately connected, as in the picture of quantum critical ferroelectricity(4). Here, we show that in Sr1-xCaxTiO3-delta (0.002 < x < 0.009, delta < 0.001) the ferroelectric order coexists with dilute metallicity and its superconducting instability in a finite window of doping. At a critical carrier density, which scales with the Ca content, a quantum phase transition destroys the ferroelectric order. We detect an upturn in the normal-state scattering and a significant modification of the superconducting dome in the vicinity of this quantum phase transition. The enhancement of the superconducting transition temperature with calcium substitution documents the role played by ferroelectric vicinity in the precocious emergence of superconductivity in this system, restricting possible theoretical scenarios for pairing.