Heavy fermions, quantum criticality, and unconventional superconductivity in filled skutterudites and related materials

Andraka, Bohdan¹ 

[1] Univ. of Florida, Gainesville, FL (United States)

关键词: Heavy fermions;    unconventional superconductivity;    praseodymium;   

DOI  :  10.2172/1179456
RP-ID  :  DOE-UF--ER45748
PID  :  OSTI ID: 1179456

学科分类：凝聚态物理

美国|英语

来源: SciTech Connect

【 摘 要 】

The main goal of this program was to explore the possibility of novel states and behaviors in Pr-based system exhibiting quantum critical behavior, PrOs???Sb??????. Upon small changes of external parameter, such as magnetic field, physical properties of PrOs???Sb?????? are drastically altered from those corresponding to a superconductor, to heavy fermion, to field-induced ordered phase with primary quadrupolar order parameter. All these states are highly unconventional and not understood in terms of current theories thus offer an opportunity to expand our knowledge and understanding of condensed matter. At the same time, these novel states and behaviors are subjects to intense international controversies. In particular, two superconducting phases with different transition temperatures were observed in some samples and not observed in others leading to speculations that sample defects might be partially responsible for these exotic behaviors. This work clearly established that crystal disorder is important consideration, but contrary to current consensus this disorder suppresses exotic behavior. Superconducting properties imply unconventional inhomogeneous state that emerges from unconventional homogeneous normal state. Comprehensive structural investigations demonstrated that upper superconducting transition is intrinsic, bulk, and unconventional. The high quality of in-house synthesized single crystals was indirectly confirmed by de Haas-van Alphen quantum oscillation measurements. These measurements, for the first time ever reported, spanned several different phases, offering unprecedented possibility of studying quantum oscillations across phase boundaries.