Strong orbital fluctuations in multipolar ordered states of PrV sub(2)Al sub(20)

• Published in: Journal of magnetism and magnetic materials Vol. 400; pp. 66 - 69
• Main Authors: Matsumoto, Yosuke, Tsujimoto, Masaki, Tomita, Takahiro, Sakai, Akito, Nakatsuji, Satoru
• Format: Journal Article
• Language: English
• Published: 01.02.2016
• Subjects: Entropy; Fluctuation; Kondo effect; Orbitals; Order disorder; Power law; Quadrupoles
• ISSN: 0304-8853
• DOI: 10.1016/j.jmmm.2015.07.113

PrT sub(2)Al sub(20) (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 Gamma sub(3) crystal electric field ground doublet with the well separated excited state. In particular, PrV sub(2)Al sub(20) 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 PrV sub(2)Al sub(20). Our detailed analyses revealed that the resistivity indicates power law temperature dependence proportional to T super(3). Furthermore, we pointed out that the 4f electron contribution to the specific heat also exhibits power law behavior proportional to T super(4). Both observations are in a sharp contrast to the gapped behavior found in PrTi sub(2)Al sub(20) and indicate the strong c-f hybridization and strong orbital fluctuations in PrV sub(2)Al sub(20). In addition, the 4f electron contribution to the entropy in PrV sub(2)Al sub(20) reaches only 50% of View the MathML source Rln2 at an orbital ordering at T=0.75 K, suggesting another 50% of View the MathML source Rln2 expected for Gamma sub(3) doublet is already released at higher temperature possibly due to quadrupole Kondo effect.