Magnetic behavior of cubic laves phase RMn 2 ( rmR = Gd, DyandHo) compounds

Abstract

Magnetization studies have been carried out on the cubic Laves phase (C15) type) intermetallic compounds GdMn 2, DyMn 2 and HoMn 2 at various applied fields in the temperature range 4.2 to 300 K. All compounds show evidence of magnetic ordering at low temperatures. A peak in the magnetization versus temperature curve is observed in zero field cooled samples of GdMn 2 and DyMn 2 but not in HoMn 2. This is taken to imply ferrimagnetic ordering between the rare earth and Mn moments. The Mn moment is estimated to be approximately 2μ B in GdMn 2. It appears that Mn carried no localized moment in HoMn 2. An anomaly in magnetization of GdMn 2 is observed around 95 K. The Mn moment appears to decrease in RMn 2 compounds while crossing the rare earth series from Gd to Ho. No Mn moment is known in hexagonal Laves phases (C14 type) compounds ErMn 2 and TmMn 2. A virtual bound state picture of Mn-3d electrons is suggested to explain the structure change and the Mn moment collapse in the RMn 2 compounds.