题　目：Unusual interplay between magnetism and superconductivity in CeAu2Si2 under pressure
报告人：任之(浙江西湖高等研究院)
时　间：4月5日（周三），下午3:00-4:00
地　点：南校区第一实验楼423会议室

报告摘要：

High pressure provides a powerful means for exploring theunconventional superconductivity which emerges mostly on the border of magnetism. In this talk, I will present the discovery of pressure-induced heavy-fermion superconductivity up to 2.5 K in the antiferromagnet CeAu₂Si₂ (T_N ≈10 K). Remarkably, it is found that the magnetic and superconducting phases overlap across an unprecedentedly wide pressure interval from 11.8 to 22.3 GPa. Moreover, both the bulk T_c and T_M are strongly enhanced when increasing the pressure from 16.7 to 20.2 GPa.  T_c reaches a maximum of 2.5 K at a pressure slightly below p_c ≈ 22.5 GPa, where magnetic order disappears. Around p_c, the depression of T_c with the increase of the residual resistivity can be well understood in terms of pair breaking by nonmagnetic disorder, strongly suggesting an unconventional pairing state. Furthermore, the scaling behavior of the resistivity provides evidence for a continuous delocalization of the Ce-4f electrons associated with a critical end point lying just above p_c. Dynamical mean-field theory calculations suggest that the peculiar behavior in pressurized CeAu₂Si₂ in comparison with CeCu₂Si₂ and CeCu₂Ge₂ might be related to its Ce-4f orbital occupancy.

Reference: Z. Ren et al., PRX 4, 031055(2014); PRB 91, 094515 (2015). 

个人简介:

任之于2009年6月获浙江大学凝聚态物理博士，随后在日本大阪大学和瑞士日内瓦大学从事博士后研究，2017年3月任浙江西湖高等研究院助理教授。研究领域包括拓扑量子材料和非常规超导体。共发表文章45篇，总计被引用超过3400次，Hirsh h-因子为28。部分成果被APS Physics Synopsis和Nature Physics News and Views以亮点进行报道。2011百篇优秀博士论文提名奖，2012年教育部高校自然科学一等奖(排名第五)。