The P-T magnetic phase diagram of SmMn(2)Ge(2).

SmMn(2)Ge(2) shows reentrant ferromagnetism. Using flux grown single crystals we find that on cooling through the Curie temperature (T(t1) = 350K) the material becomes ferromagnetic (FM). Upon further cooling, at T(t2) = 150K an antiferromagnetic (AFM) phase is reached which is stable until T(t3) = 100K when there is a transition to FM. The transitions at T(t1) and T(t2) are first order with a temperature hysteresis of about 4K. Using ac susceptibility to determine the various transition temperatures as a function of pressure (P) we find that T(t3) rapidly decreases with increasing P and at relatively low pressures falls below our measuring range (90K). T(t2) increases nearly linearly with P and reaches 330K and 11 kbar. T(t1), drops slowly with increasing P and at 11 kbar the high temperature FM region ends. An X-ray determination of the lattice parameters (at atm pressure) show that in the AFM region the a(o) lattice parameter is decreased, discontinuously changing at T(t2) and T(t3).