Magnetic properties of Er<inf>1-x</inf> Dy<inf>x</inf>Al<inf>2</inf> (0x1) compounds in low applied fields

Low field magnetic properties of the Laves phase RAl2 compounds (where R is a mixture of Er and Dy, i.e., Er1-x Dyx and x=0, 0.1, 0.14, 0.18, 0.25, 0.33, 0.5, and 1) have been studied. These compounds order ferromagnetically, and the middle members show both metastability in a narrow temperature window within the ferromagnetically ordered state and signatures of first order transitions in low applied fields. Results of first principles electronic structure calculations on Er0.75 Dy0.25 Al2 indicate a significant difference in the spin polarization in the 5d states of Er3+ and Dy3+ moments. In addition, anisotropic exchange and crystalline electric field effects arise from the random distribution of rare earth ions in the lattice. These and quadrupolar effects triggered by aspherical charge distributions of Er3+ and Dy3+ ions may compete and lead to the low temperature anomalies observed in low field magnetization data. © 2010 American Institute of Physics.