Magnetism and superconductivity in strongly correlated systems -- Magnétisme et supraconductivité dans des systèmes fortement corrélés

物理性质由粒子间相互作用决定的物质称为强关联物质。这些相互作用在低温下产生新的基态，其中超导性和磁性是最重要的。必须通过实验研究这些状态之间的竞争、共存和相互关系，以了解它们在未来设备中的潜力。在这些材料中，具有低维特性的有机导体特别有吸引力，因为非常规的超导状态与磁性竞争。它们也被认为是理想的系统，因为在实验室中可达到的能量尺度（温度，压力，磁场）。超导薄膜，可以更容易地纳入新的设备和磁性材料同时显示磁性和电极化（多铁性）也将进行研究。我们建议对这些系统进行超声和微波实验，以解决与识别和表征新的超导和/或磁状态相关的重要问题。这样的实验是必不可少的，以维持这些材料的理论模型的建设。这些实验将作为温度（低2-300 K和超低20 mK），磁场（18特斯拉作为方向的函数）和静水压力（12 kbar）的函数进行。这些测量可能构成关键实验，以完成我们对材料的理解。

Materials whose physical properties are dominated by particle-particle interactions are called strongly correlated. These interactions produce novel ground states at low temperatures among which superconductivity and magnetism are the most important. The competition, the coexistence and the interrelation between these states must be investigated experimentally to appreciate their potential in future devices. Among these materials, organic conductors with a low-dimensional character are particularly attractive because an unconventional superconducting state is in competition with magnetism. They are also considered as ideal systems because of energy scales (temperature, pressure, magnetic field) attainable in laboratories. Superconducting thin films which can be more easily incorporated in novel devices and magnetic materials showing simultaneously magnetism and electric polarization (multiferroics) will also be studied. We propose to perform ultrasonic and microwave experiments on these systems to address important issues related to the identification and characterization of the novel superconducting and/or magnetic states. Such experiments are essential to sustain the construction of theoretical models of these materials. These experiments will be performed as a function of temperature (low 2-300 K and ultra-low 20 mK), of magnetic field (18 Tesla as a function of orientation) and hydrostatic pressure (12 kbar). These measurements can potentially constitute key experiments to complete our understanding of the materials.