J. Phys. Soc. Jpn. 72 (2003) pp. 1516-1522 |Next Article| |Table of Contents|
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Magnetic Phase Diagram of the Heavy Fermion Superconductor PrOs4Sb12
1Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581
2Department of Physics, Tokyo Metropolitan University, Minami-Ohsawa 1-1, Hachioji, Tokyo 192-0397
(Received February 3, 2003)
We investigated the magnetic phase diagram of the first Pr-based heavy fermion superconductor PrOs4Sb12 by means of high-resolution dc magnetization measurements in low temperatures down to 0.06 K. The temperature dependence of the magnetization M(T) at 0.1 kOe exhibits two distinct anomalies at Tc1=1.83 K and Tc2=1.65 K, in agreement with the specific heat measurements at zero field. Increasing magnetic field H, both Tc1(H) and Tc2(H) move toward lower temperatures without showing a tendency of intersecting to each other. Above 10 kOe, the transition at Tc2(H) appears to merge into a line of the peak effect which is observed near the upper critical field Hc2 in the isothermal M(H) curves, suggesting a common origin for these two phenomena. The presence of the field-induced ordered phase (called phase A here) is confirmed for three principal directions above 40 kOe, with the anisotropic A-phase transition temperature TA: TA > TA >TA. The present results are discussed on the basis of crystalline-electrical-field level schemes with a non-magnetic ground state, with emphasis on a Γ1 singlet as the possible ground state of Pr3+ in PrOs4Sb12.
©2003 The Physical Society of Japan
KEYWORDS:PrOs4Sb12, heavy-fermion superconductor, mixed state, magnetization, phase diagram, crystalline electric field effect
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