Superconductivity in the Ferroquadrupolar State in the Quadrupolar Kondo Lattice PrTi2Al20

The cubic compound PrTi₂Al₂₀ is a quadrupolar Kondo lattice system that exhibits quadrupolar ordering due to the non-Kramers Γ₃ ground doublet and has strong hybridization between $4f$ and conduction electrons. Our study using high-purity single crystal reveals that PrTi₂Al₂₀ exhibits type-II superconductivity at Tc = 200 mK in the nonmagnetic ferroquadrupolar state. The superconducting critical temperature and field phase diagram suggests moderately enhanced effective mass of m^*/m₀ ~ 16.