PrV2Al20 is the heavy fermion superconductor based on the cubic Gamma3 doublet that exhibits non- magnetic quadrupolar ordering below ~ 0.6 K. Our magnetotransport study on PrV2Al20 reveals field-induced quadrupolar quantum criticality at Hc ~ 11 T a
pplied along the [111] direction. Near the critical field Hc required to suppress the quadrupolar state, we find a marked enhancement of the resistivity rho(H, T), a divergent effective mass of quasiparticles and concomitant non-Fermi liquid (NFL) behavior (i.e. rho(T) ~ T^n with n < 0.5). We also observe the Shubnikov de Haas-effect above ?Hc, indicating the enhanced effective mass m/m0 ~ 10. This reveals the competition between the nonmagnetic Kondo effect and the intersite quadrupolar coupling, leading to the pronounced NFL behavior in an extensive region of T and H emerging from the quantum critical point.
PrV$_2$Al$_{20}$ is a rare example of a heavy fermion system based on strong hybridization between conduction electrons and nonmagnetic quadrupolar moments of the cubic $Gamma_3$ ground doublet. Here, we report that a high-quality single crystal of P
rV$_2$Al$_{20}$ exhibits superconductivity at $T_{rm c}=$ 50 mK in the antiferroquadrupole-ordered state under ambient pressure. The heavy fermion character of the superconductivity is evident from the specific heat jump of $Delta C/T sim 0.3$ J/mol K$^2$ and the effective mass $m^*/m_0 sim 140$ estimated from the temperature dependence of the upper critical field. Furthermore, the high-quality single crystals exhibit double transitions at $T_{rm Q}$ = 0.75 K and $T^{*}$ = 0.65 K associated with quadrupole and octapole degrees of freedom of the $Gamma_3$ doublet. In the ordered state, the specific heat $C/T$ shows a $T^3$ dependence, indicating the gapless mode associated with the quadrupole and/or octapole order. The strong sensitivity to impurity of the superconductivity suggests unconventional character due to significant quadrupolar fluctuations.
