Magnetic transitions in Tb0.7Nd0.3Mn2Ge2 compound

Abstract

In this article we report a new compound, Tb0.7Nd0.3Mn2Ge2, which behaves like SmMn2Ge2, a compound with reentrant ferromagnetic order. Magnetization and thermal expansion measurements have been performed to study polycrystalline Tb0.7Nd0.3Mn2Ge2. Temperature dependent magnetization data shows that from 800 to 426 K the sample behaves like a paramagnet. A Néel transition is observed at 426 K (T4) and the antiferromagnetic phase persists until 334 K (T3). From 334 K (T3) to 277 K (T2) the sample exists in a ferromagnetic state. At 277 K (T2) the sample transforms into an antiferromagnetic phase. Interestingly, at 117 K (T1) the sample enters into a ferromagnetic-like phase. Thermal expansion study shows a sharp change in the sample dimension around T1 (125 K). This change in the dimension most likely triggers the reentrant magnetic transition (T1) observed in the magnetization measurement. The sharp change in thermal expansion suggests this transition at T1 to be of first order. The relatively small and shallow dimensional change around T2 (275 K) implies a weak first order transition. The dimensional changes found at the two transitions strongly suggest that Mn–Mn intralayer distance plays an important role in the multiple magnetic phases in Tb0.7Nd0.3Mn2Ge2.