Superconducting Gap Structure of Single Crystals Organic Superconductor lambda-(BETS)2GaCl4 Studied by µSR

The quasi-2-dimensional organic superconductor lambda-(BETS)2GaCl4 is one of the key materials in strongly correlated systems because of the distinct geometrical structure of electron-electron correlation effect in the molecular conducting plane. The TF-muSR measurements have been done in ~130 mg aligned crystals in the perpendicular field configuration in order to determine the temperature dependence of superfluid density. The analyses intriguingly show that superconducting (SC) gap has steeper nodes structure than that of d-wave nodes by factor ~3. A decomposition of SC gap is necessary in order to reveal the SC gap structure in this system which can be described by a mixture of multi-gap symmetries. Thus, we propose to measure systematic TF-muSR measurements in other two magnetic field directions, along with the other two crystal axes, by preparing a different aligned crystals setup.

准二维有机超导体λ-(BETS)₂GaCl₄是强关联系统中的关键材料之一，因其分子导电平面内电子-电子关联效应具有独特的几何结构而受到广泛关注。为了探明超流密度的温度依赖性，研究团队已针对约130毫克的取向晶体开展了横向场μ子自旋弛豫（Transverse Field muon Spin Relaxation, TF-muSR）测量，实验采用垂直场配置。分析结果显示，该体系的超导（SC）能隙节点结构比d波节点更为陡峭，陡峭程度约为d波节点的3倍。由于该体系的超导能隙可由多种能隙对称性混合描述，因此需要对超导能隙进行分解以揭示其内在结构。据此，我们提出通过制备不同的取向晶体装置，针对沿其余两个晶轴的另外两个磁场方向开展系统性的TF-muSR测量。