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Hidden low‐temperature instability in PrOs 4 Sb 12
Author(s) -
Grube K.,
Zaum S.,
Bauer E. D.,
Maple M. B.,
Löhneysen H. v.
Publication year - 2010
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.200983070
Subject(s) - instability , condensed matter physics , magnetic field , atmospheric temperature range , phase transition , electron , entropy (arrow of time) , physics , materials science , thermodynamics , quantum mechanics , mechanics
The low‐temperature behavior of many correlated electron systems is characterized by the appearance of macroscopically ordered states that show a dome‐shaped evolution of their transition temperatures as a function of non‐thermal control parameters. In the heavy‐fermion compound PrOs 4 Sb 12 , a field‐induced phase emerges in a magnetic field range between $B \approx 4.5$ and 13.5 T. The phase is characterized by antiferroquadrupolar (AFQ) ordering of the Pr 3+ ions. We measured the specific heat of PrOs 4 Sb 12 single crystals in magnetic fields up to $B = 14$ T parallel to the crystallographic [100] direction to determine the entropy S as a function of T and B . Above the maximum AFQ transition temperature, the entropy $S(T = {\rm const},B)$ reveals a pronounced maximum. We show that this maximum can be related to a low‐temperature instability which is produced by the degeneracy of the lowest crystalline electric field (CEF) energy levels.