METAMAGNETISM OF ITINERANT D-ELECTRONS IN LAVES PHASE-COMPOUNDS LU(CO1-XALX)2

Representative first-order metamagnetic transitions with a large hysteresis have been observed for x less-than-or-equal-to 0.06. The transition field H(c) for x = 0.06 is 220 kOe at 4.2 K. Simple but strong ferromagnetism is found for x > 0.12. A mixing state of ferromagnetic and paramagnetic states of Co is assured for 0.06 less-than-or-equal-to chi less-than-or-equal-to 0.12. The paramagnetic component in the state also exhibits the metamagnetic transition. By surveying the temperature dependence of metamagnetism, a boundary temperature of the first- and second-order metamagnetic transitions, and a first-order magnetic transition in thermomagnetic curves are found for the first time. In relation to the magnetic phase transitions the critical parameters T1 and H1 are introduced and discussed. Finally a magnetic phase diagram is presented.