PrT2Al20 (T=Ti, V) are ideal systems to study the quadrupole Kondo effect and quantum criticality arising from orbital degrees of freedom. The both systems have the nonmagnetic cubic Γ3 crystal electric field ground doublet with the well separated excited state. In particular, PrV2Al20 exhibits 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 an orbital quantum critical point. Here we report the anomalous metallic behaviors found in a pure single crystal of PrV2Al20. Our detailed analyses revealed that the resistivity indicates power law temperature dependence proportional to T3. Furthermore, we pointed out that the 4f electron contribution to the specific heat also exhibits power law behavior proportional to T4. Both observations are in a sharp contrast to the gapped behavior found in PrTi2Al20 and indicate the strong c-f hybridization and strong orbital fluctuations in PrV2Al20. In addition, the 4f electron contribution to the entropy in PrV2Al20 reaches only 50% of Rln2 at an orbital ordering at T=0.75 K, suggesting another 50% of Rln2 expected for Γ3 doublet is already released at higher temperature possibly due to quadrupole Kondo effect.
Matsumoto, Y., Tsujimoto, M., Tomita, T., Sakai, A., & Nakatsuji, S. (2016). Strong orbital fluctuations in multipolar ordered states of PrV2Al20. Journal of Magnetism and Magnetic Materials, 400, 66–69. https://doi.org/10.1016/j.jmmm.2015.07.113