Quantum criticality at the superconductor-insulator transition revealed by specific heat measurements.
Quantum criticality at the superconductor-insulator transition revealed by specific heat measurements.
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DOI：
10.1038/ncomms14464
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发表时间：
2017-02-22
影响因子：
16.6
通讯作者：
Bourgeois O
中科院分区：
文献类型：
--
作者：
Poran S;Nguyen-Duc T;Auerbach A;Dupuis N;Frydman A;Bourgeois O
超导体-绝缘体转变（SIT）被认为是由零温度下的量子涨落驱动的量子相变的一个很好的例子。量子临界点的特征在于发散的关联长度和消失的能量标度。量子临界附近的低能量波动可以通过比热测量来实验检测。在这里，我们使用一个独特的高灵敏度的实验来测量CP的二维颗粒状铅膜通过SIT。比热表明通常的跳跃在平均场超导转变温度标志着库珀对形成的开始。随着膜厚向SIT方向调整，膜厚相对不变，而跃变幅度和低温比热显著增加。这种行为被认为是在量子相变附近的量子临界的热力学指纹。检测量子相变的量子涨落的热力学特征是具有挑战性的。在这里，Poran等人报告了当颗粒状Pb膜的厚度接近超导体-绝缘体转变时比热的显著增加。
The superconductor–insulator transition (SIT) is considered an excellent example of a quantum phase transition that is driven by quantum fluctuations at zero temperature. The quantum critical point is characterized by a diverging correlation length and a vanishing energy scale. Low-energy fluctuations near quantum criticality may be experimentally detected by specific heat, cp, measurements. Here we use a unique highly sensitive experiment to measure cp of two-dimensional granular Pb films through the SIT. The specific heat shows the usual jump at the mean field superconducting transition temperature marking the onset of Cooper pairs formation. As the film thickness is tuned towards the SIT, is relatively unchanged, while the magnitude of the jump and low-temperature specific heat increase significantly. This behaviour is taken as the thermodynamic fingerprint of quantum criticality in the vicinity of a quantum phase transition. To detect thermodynamic signatures of quantum fluctuations for quantum phase transitions is challenging. Here, Poran et al. report a significant increase in the specific heat when the thickness of granular Pb films approaches a superconductor-insulator transition.