Magnetic dilution in the frustrated ferromagnetic pyrochlore system, (Dy1-xLux)(2)Mn2O7

摘要

To gain insights into the magnetic interactions in ferromagnetic R2Mn2O7 pyrochlores (R = rare earth element), we systematically investigated the effects of magnetic dilution in the (Dy1-xLux)(2)Mn2O7 system by gradually increasing the concentration of nonmagnetic Lu3+ ions at the R-cation site. Single-phase samples were successfully obtained for the entire substitution range of 0.0 <= x <= 1.0 through ultra-high-pressure synthesis. All the samples display sharp increases in both dc and ac magnetic susceptibilities below similar to 40 K, followed by an appearance of FC-ZFC irreversibilities and broad frequency-dependent maxima at lower temperatures, indicative of a re-entrant spin-glass like behavior. With increasing x, both the ferromagnetic transition temperature and the cusp temperature in the ZFC susceptibility curve were found to get monotonically lowered. It was concluded that Dy3+-Dy3+ and/or Dy3+-Mn4+ magnetic interactions affect the magnetic properties of (Dy, Lu)(2)Mn2O7. (c) 2007 Elsevier Ltd. All rights reserved.