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

Abstract In the layered compound Gd 0.925 La 0.075 Mn 2 Ge 2 , a reentrant ferrimagnetism having a para-( T C )-ferri-( T t1 )-antiferro-( T t2 )-ferri transition with decreasing temperature was observed. Between T t1 and T t2 , a field-induced matamagnetism from collinear antiferromagnetism to ferrimagnetism appears, accompanied with a multi-step transition, the so-called “devil's stair-case”. In addition, a giant magnetoresistance effect (Δ ρ / ρ ∼15%) was also observed at the metamagnetic transition. These unusual features will be characteristic in layered antiferromagnetism.