Materials World Network: Microscopic Study of Inhomogeneous Supeconductivity

这是格勒诺布尔高磁场实验室（GHMFL）和布朗大学之间的合作研究成果。本研究的总体主题是微观研究非均匀超导性，即富尔德-费雷尔-拉金-奥夫奇尼科夫（FFLO）态。这一现象的研究不仅与凝聚态物理有关，而且与基本粒子和原子物理也有关。在低温下，磁场破坏ii型超导体的超导性可以通过两种方式完成。由于自旋自由度与场的耦合（泡利顺磁性）或场对轨道自由度的影响，库柏对可能会破裂。当泡利对破断主导轨道效应时，预计在Hc2附近会出现一个新的FFLO相。在这种新状态下，超导序参量在实空间中振荡。有实验证据表明，这一相可能存在于某些重费米子和有机超导体中。将通过核磁共振技术对这种全新的超导状态进行彻底的微观研究。这种局部技术非常适合所提议的任务。美国团队带来了超导材料高领域研究的专业知识；格勒诺布尔小组带来了低维系统中磁场诱导现象研究方面的专业知识。此外，格勒诺布尔高磁场实验室提供了在极低温度（40 mK）和高达33 t的磁场下进行拟议研究的设施。该合作为开发这些新量子态的核磁共振微观研究提供了独特的机会。此外，它将允许美国学生在最先进的设施中参与国际研究活动，再加上传统的培训，将为他们在学术界或工业界竞争激烈的职业生涯做好准备。该奖项由材料研究部和国际科学与工程办公室共同资助。

This is a collaborative research effort between the Grenoble High Magnetic Field Laboratory (GHMFL) and Brown University. The general theme of this research is the microscopic study of inhomogeneous superconductivity, i.e., the Fulde-Ferrell-Larkin-Ovchinikov (FFLO) state. The study of this phenomenon is relevant not only to condensed matter physics but to elementary-particle and atomic physics as well. At low temperatures, the destruction of superconductivity by a magnetic field in a type-II superconductor can be accomplished in two ways. Cooper pairs may break up either because of the coupling of the spin degrees of freedom to the field (Pauli paramagnetism) or because of the effect of the field on the orbital degree of freedom. A novel FFLO phase is predicted to occur in the vicinity of Hc2 when Pauli pair breaking dominates over the orbital effects. In this new state the superconducting order parameter oscillates in real space. There is experimental evidence that this phase possibly exists in certain heavy-fermion and organic superconductors. A thorough microscopic study of this fundamentally new superconducting state is to be undertaken through the NMR technique. This local technique is ideal for the proposed task. The U.S. group brings expertise in high field studies of superconducting materials; the Grenoble group brings expertise in the study of magnetic field-induced phenomena in low dimensional systems. In addition, the Grenoble High Magnetic Field Laboratory offers facilities for the proposed studies at very low temperatures, 40 mK, in magnetic fields up to 33 T. The collaboration offers a unique opportunity for developing the NMR microscopic studies of these new quantum states. In addition, it will allow US students to participate in international research activities at state-of-the-art facilities that together with traditional training will prepare them for competitive careers in academia or industry. This award is co-funded by the Division of Materials Research and the Office of International Science and Engineering.