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

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)2Mn2O7 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 ∼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)2Mn2O7.