Sumario: | We studied in detail the low temperature/high magnetic field phases of [Formula presented] single crystals with specific heat, magnetocaloric effect, and magnetoresistance in magnetic fields up to 45 T. Data obtained down to 0.5 K, and extrapolated to [Formula presented], show a suppression of the hidden-order phase at [Formula presented] and the appearance of a new phase for magnetic fields in excess of [Formula presented] observed only at temperatures lower than 6 K. In turn, complete suppression of this high field state is attained at a critical magnetic field [Formula presented]. No phase transitions are observed above 40 T. We discuss our results in the context of itinerant versus localized [Formula presented] electrons. © 2002 The American Physical Society.
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