Jung Soon-Gil, Seo Soonbeom, Lee Sangyun, Bauer Eric D, Lee Han-Oh, Park Tuson
Center for Quantum Materials and Superconductivity (CQMS), Department of Physics, Sungkyunkwan University, Suwon, 16419, South Korea.
Los Alamos National Laboratory, Los Alamos, NM, 87545, USA.
Nat Commun. 2018 Jan 30;9(1):434. doi: 10.1038/s41467-018-02899-5.
Generally, studies of the critical current I are necessary if superconductors are to be of practical use, because I sets the current limit below which there is a zero-resistance state. Here, we report a peak in the pressure dependence of the zero-field I, I(0), at a hidden quantum critical point (QCP), where a continuous antiferromagnetic transition temperature is suppressed by pressure toward 0 K in CeRhIn and 4.4% Sn-doped CeRhIn. The I(0)s of these Ce-based compounds under pressure exhibit a universal temperature dependence, underlining that the peak in zero-field I(P) is determined predominantly by critical fluctuations associated with the hidden QCP. The dc conductivity σ is a minimum at the QCP, showing anti-correlation with I(0). These discoveries demonstrate that a quantum critical point hidden inside the superconducting phase in strongly correlated materials can be exposed by the zero-field I, therefore providing a direct link between a QCP and unconventional superconductivity.
一般来说，如果要使超导体具有实际用途，就必须对临界电流I进行研究，因为I设定了电流限制，低于该限制时会出现零电阻状态。在此，我们报告了在一个隐藏的量子临界点（QCP）处，零场I即I(0)的压力依赖性出现峰值，在该点，CeRhIn和4.4% Sn掺杂的CeRhIn中连续反铁磁转变温度被压力压低至0 K。这些基于铈的化合物在压力下的I(0)呈现出普遍的温度依赖性，这表明零场I(P)中的峰值主要由与隐藏QCP相关的临界涨落决定。直流电导率σ在QCP处最小，与I(0)呈反相关。这些发现表明，强关联材料中超导相内部隐藏的量子临界点可以通过零场I暴露出来，因此在QCP和非常规超导之间建立了直接联系。
