Ferromagnetic quantum criticality and superconductivity in Yb-based heavy-fermion systems

镱基重费米子系统中的铁磁量子临界性和超导性

• 批准号: 323240951
• 负责人: Dr. Manuel Brando
• 金额: --
• 依托单位: Max-Planck-Institut für Chemische Physik fester Stoffe (MPI CPfS)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2016
• 资助国家: 德国
• 起止时间: 2015-12-31 至 2019-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/323240951?language=en
• 关键词: Ferromagnetic; quantum; criticality; superconductivity; Yb

Ferromagnetic quantum criticality and the occurrence of unconventional superconductivity are central research topics among strongly correlated electron systems. For heavy-fermion systems with trivalent Yb, this is an experimental challenge, because the number of Yb-based compounds showing these types of phenomena is very limited. This is in stark contrast to the huge number of existing antiferromagnetic Kondo-lattice systems and the established occurrence of superconductivity in Ce-based heavy-fermion materials. One important reason for this imbalance is due to the high-vapor pressure of Yb, which makes the crystal growth of these materials very difficult. The recent discoveries of ferromagnetic quantum criticality in YbNi4P2 and the emergence of superconductivity in YbRh2Si2, under the participation of both proposers, was therefore an essential step forward to experimentally investigate these phenomena in Yb-based heavy-fermion metals.The main objectives of this research proposal are the single crystal growth and the low-temperature characterization of Yb-based heavy-fermion compounds close to a magnetic quantum critical point. We will focus on ferromagnetic quantum criticality as well as the occurrence of superconductivity in the vicinity of the quantum critical point. For this purpose, we will investigate in detail (i) YbNi4P2 and related substitution series, (ii) Yb(RhCo)2Si2 and (iii) YbRh2Si2 single crystals. Several crystal growth techniques will be employed to grow very pure single crystals with low amount of defects and reproducible physical properties, which will be characterized by state-of-the art low-temperature physical measurements.

铁磁量子临界性和非常规超导性的出现是强关联电子系统的研究热点。对于具有三价Yb的重费米子系统，这是一个实验挑战，因为显示这些类型现象的Yb基化合物的数量非常有限。这与大量现有的反铁磁近藤晶格系统和在Ce基重费米子材料中建立的超导性形成鲜明对比。这种不平衡的一个重要原因是由于Yb的高蒸气压，这使得这些材料的晶体生长非常困难。在两位提出者的参与下，最近在YbNi 4P 2中发现了铁磁量子临界性，在YbRh 2Si 2中出现了超导性，本研究的主要目标是Yb基重费米子金属的单晶生长和低温特性研究。接近磁量子临界点的费米子化合物我们将集中在铁磁量子临界性以及在量子临界点附近的超导性的发生。为此，我们将详细研究（i）YbNi_4P_2和相关替代系列，（ii）Yb（RhCo）_2Si_2和（iii）YbRh_2Si_2单晶。将采用多种晶体生长技术来生长非常纯的单晶，具有低缺陷量和可重现的物理性能，其特征将通过最先进的低温物理测量来表征。