Heavy Fermion Superconductivity in Non-magnetic Cage Compound PrV2Al20

TMU International Symposium on "New Quantum Phases Emerging from Novel Crystal Structure"

Matsumoto, Yosuke^1 ; Tsujimoto, Masaki^1 ; Tomita, Takahiro^1 ; Sakai, Akito^1 ; Nakatsuji, Satoru^1

Institute for Solid State Physics, University of Tokyo, Kashiwa

277-8581, Japan^1

关键词: Conduction electrons;    Crystal electric field;    Electronic specific heat coefficient;    Heavy-fermion superconductivity;    Orbital degrees of freedom;    Quantum critical points;    Temperature dependence;    Upper critical fields;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/683/1/012013/pdf
DOI  :  10.1088/1742-6596/683/1/012013

来源: IOP

【 摘 要 】

PrT2Al20(T = Ti, V) are ideal systems to study the quadrupole Kondo effect and quantum criticality arising from orbital degrees of freedom. Both systems have the nonmagnetic cubic Γ3crystal electric field ground doublet with the well separated excited state. In particular, PrV2Al20exhibits anomalous metallic behavior above and below the multipolar ordering temperatures, reflecting the even stronger hybridization between f and conduction electrons possibly due to a proximity to a orbital quantum critical point. Here, we discuss the heavy fermion superconductivity (SC) of PrV2Al20in detail. The SC appears at Tc= 0.05 K with the highly enhanced effective mass (m∗ /m0∼ 140) estimated using the temperature dependence of the upper critical field. In addition, large electronic specific heat coefficient of γ ∼ 0.9 J/mol K2above Tcand the large specific heat jump at Tcof ΔC/Tc∼ 0.3 J/mol K2provide direct evidences of the heavy fermion SC. This observation indicates the first realization of the novel SC arising from the orbital fluctuation of the f electrons at ambient pressure.