High magnetic-field-induced phase transitions and refined magnetic phase diagram of Gd5Ge4.

We have performed magnetization measurements of Gd5Ge4 with little or no ferromagnetic (FM) impurities under a pulsed magnetic field up to 40 T. The results reveal previously undetected transitions between 85 and 105 K, that is, a distinct second-order antiferromagnetic (AFM)-paramagnetic (PM) transition, followed by a first-order PM-ferromagnetic (FM) transition. The distinct variation of the slope of the M(H) curves is observed around the AFM-PM transition. Combining our high-field data and those reported earlier, a new magnetic field-temperature phase diagram, in which the AFM, PM, and FM states are well separated, is constructed. [ABSTRACT FROM AUTHOR]