Unusual magnetic and transport properties of layered compound Gd0.925La0.075Mn2Ge2

In the layered compound Gd(0.925)Lao(0.075)Mn(2)Ge(2), a reentrant ferrimag netism having a para-(T-C)-ferri-(T-t1)-anti-ferro-(T-t2)-ferri transition with decreasing temperature was observed. Between T-t1 and T-t2, a field-in duced matamagnerism from collinear antiferromagnetism to ferrimagnetism app ears, accompanied with a multi-step transition, the so-called "devil's stai r-case". In addition, a giant magnetoresistance effect (Delta rho/rho simil ar to 15%) was also observed at the metamagnetic transition. These unusual features will be characteristic in layered antiferromagnetism. (C) 2000 Els evier Science B.V. All rights reserved.