Suppression of superconductivity by anisotropic strain near a nematic quantum critical point
Suppression of superconductivity by anisotropic strain near a nematic quantum critical point
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DOI：
10.1038/s41567-020-0983-9
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发表时间：
2020-08-10
期刊：
影响因子：
19.6
通讯作者：
Chu, Jiun-Haw
中科院分区：
文献类型：
--
作者：
Malinowski, Paul;Jiang, Qianni;Chu, Jiun-Haw
作者使用掺杂的BaFe 2As 2，通过将共轭场应用于向列性（应变的一种特殊形式）来测试向列性是否与铁磷属元素化物中的超导性有关，并观察到临界温度降低。在大多数非常规和高温超导体中，超导性出现在附近的超导性破坏相被化学掺杂或压力抑制时（1-7）。这导致人们相信，与超导破坏相相关的涨落对超导配对是有益的，如果不是负责的话（8，9）。验证这一假设的一个直接测试是观察超导临界温度（Tc）的降低，通过施加抑制竞争秩序的动态波动的破缺共轭场。然而，大多数非常规超导体中的竞争相位打破了平移对称性，需要空间调制的共轭场，这在实验上很难实现。在这里，我们表明，各向异性应变，共轭领域的向列性，减少了T（c）的铁磷属元素化物。对于最佳掺杂的样品，我们显示了五倍的减少ofT（c）小于百分之一的应变。对于欠掺杂样品，T（c）变为零，产生完全金属基态。除了提供直接证据证明超导态形成过程中的涨落所起的作用外，这些结果还证明了高温超导体的可调机械控制，这是超导技术应用的重要一步。
Using doped BaFe2As2, the authors test whether nematicity is linked to superconductivity in the iron pnictides by applying the conjugate field to nematicity-a specific form of strain-and observe that the critical temperature decreases.In most unconventional and high-temperature superconductors, superconductivity emerges as a nearby symmetry-breaking phase is suppressed by chemical doping or pressure(1-7). This has led to the belief that the fluctuations associated with the symmetry-breaking phase are beneficial, if not responsible, for the superconducting pairing(8,9). A direct test to verify this hypothesis is to observe a decrease of the superconducting critical temperature (T-c) by applying the symmetry-breaking conjugate field that suppresses the dynamic fluctuations of the competing order. However, most of the competing phases in unconventional superconductors break translational symmetry, requiring a spatially modulated conjugate field that is difficult to realize experimentally. Here, we show that anisotropic strain, the conjugate field of nematicity, reduces theT(c)of an iron pnictide. For optimally doped samples we show a fivefold reduction ofT(c)with less than one per cent of strain. For underdoped samples,T(c)becomes zero yielding a fully metallic ground state. In addition to providing direct evidence of the role played by the nematic fluctuations in the formation of the superconducting state, these results demonstrate tunable mechanical control of a high-temperature superconductor, an important step forward for technological applications of superconductivity.