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Searching for the Field-Induced Non-Magnetic Phase
Transition and the Quantum Criticality
Yasuyuki SHIMURA
Institute for Solid State Physics (ISSP), The University of Tokyo, Kashiwa, Chiba 277-8581,
Japan,
National High Magnetic Field Laboratory (NHMFL), Florida State University, Tallahassee,
Florida 32310, USA
In the strongly correlated electron systems, quantum phase transition realized at ~ 0
K can be induced by magnetic field, pressure or chemical substitution. In the vicinity of the
transition point between magnetic ordered phases and paramagnetic phase, quantum critical
behavior like non-Fermi liquid behavior and/or heavy fermion superconductivity have been
observed. The quantum phase transition without magnetic instability also exists like valence
transition, orbital (quadrupolar) transition, and so on. However the quantum criticality has not
been clarified well.
Novel phenomena induced by strong hybridization between quadrupolar moments
and conduction electrons have attracted recent intensive attention. One of the promising
compound for the study is the cubic caged compound PrV2Al20, which has a strong
hybridization between conduction electrons and the 4f- non-magnetic ground doublet having
only orbital moments [1]. In fact, anomalous metallic state emerges owing to the putative
“two-channel” Kondo effect using the orbital moments (electric quadrupole moments).
Below the antiferro-quadrupole (AFQ) ordering temperature of T Q = 0.6 K [1,2], PrV2Al20
exhibits the heavy-fermion superconductivity with a strongly enhanced effective mass (m * ~
140 m 0) at T SC = 0.05 K [3].
Recently, we have measured the magnetoresistance in PrV2Al20 down to 0.4 K up to
31 T for H // [111] [4]. The AFQ phase is found to be suppressed by the strong magnetic field
at H c ~ 11 T. In the vicinity of the critical field, the temperature dependence of the resistivity
shows sub-linear T-dependence, clearly deviated from the Fermi-liquid behavior. This is the
first observation of the field-induced quadrupolar quantum criticality. In addition, we found
the heavy-cyclotron effective mass up to m*/m0 ~ 10 from the Shubnikov-de Haas Oscillation.
In this presentation, we will discuss the field-induced quantum criticality due to the
quadrupole moments in PrV2Al20. If we have a time, I will also talk about the recent results of
the intermediate valence compounds a-YbAlB4 isostructural to the Yb-based heavy fermion
superconductor b-YbAlB4 under high magnetic field and pressure [5].
[1] A. Sakai and S. Nakatsuji, J. Phys. Soc. Jpn. 80, 063701 (2011).
[2] Y. Shimura, Y. Ohta, T. Sakakibara, A. Sakai and S. Nakatsuji, J. Phys. Soc. Jpn. 82,
043705 (2013).
[3] M. Tsujimoto, Y, Matsumoto, T. Tomita, A. Sakai, and S. Nakatsuji, Phys. Rev. Lett. 113,
267001 (2014).
[4] Y. Shimura, M. Tsujimoto, B. Zeng, L. Balicas, A. Sakai, and S. Nakatsuji,
arXiv:1412.4120 (2014).
[5] Y. Matsumoto et al., Science 331, 316 (2011).