title: High magnetic field phase diagram of PrOs4Sb12.
abstract: The magnetic phase diagram of PrOs4Sb12 has been investigated by specific heat measurements between 8 and 32 T. A new Schottky anomaly, due to excitations between two lowest crystalline-electric-field (CEF) singlets, has been found for both H parallel (100) and H parallel (110) above the field where the field-induced ordered phase (FIOP) is suppressed. The constructed H-T phase diagram shows weak magnetic anisotropy and implies a crossing of the two CEF levels at about 8-9 T for both field directions. These results provide an unambiguous evidence for the Gamma(1) singlet being the CEF ground state and suggest the level crossing (involving lowest CEF levels) as the driving mechanism of FIOP.
authors.affiliation: Department of Physics, University of Florida, P.O. Box 118440, Gainesville, Florida 32611-8440, USA.
authors.forename: C R
authors.initials: CR
authors.lastname: Rotundu
authors.forename: H
authors.initials: H
authors.lastname: Tsujii
authors.forename: Y
authors.initials: Y
authors.lastname: Takano
authors.forename: B
authors.initials: B
authors.lastname: Andraka
authors.forename: H
authors.initials: H
authors.lastname: Sugawara
authors.forename: Y
authors.initials: Y
authors.lastname: Aoki
authors.forename: H
authors.initials: H
authors.lastname: Sato