Unconventional Superconductivity and Heavy Fermion Behavior in PrOs4Sb12

摘要

Research carried out during the last several years on the heavy fermion superconductor PrOs4Sb12 is reviewed. The compound PrOs4Sb12 exhibits unconventional strong coupling superconductivity below a superconducting critical temperature T c = 1.85 K. The superconducting state breaks time reversal symmetry, apparently consists of several distinct superconducting phases, some of which may have point nodes in the energy gap, and may involve triplet spin pairing of electrons. The determination of the Pr3+ energy level scheme in the crystalline electric field, as well as the discovery and characterization of the high field-ordered phase (HFOP), which has been identified with antiferroquadrupolar order, are described. Studies of the substitutional systems Pr(Os1−x Ru x )4Sb12, Pr1−x La x Os4Sb12, and Pr1−x Nd x Os4Sb12 are summarized and compared.