High - pressure high - temperature ( HPHT ) synthesis and magnetism of MSr 2 Y 1 . 5 Ce 0 . 5 Cu 2 O 10 compounds with M = Ru , Mn , and Cr

We report synthesis and magnetization of MSr2Y1.5Ce0.5Cu2O10 (M/Y-1222) compounds with M = Ru, Mn and Cr by HPHT. They are synthesized at high-pressure of 6 GPa in optimized temperatures of up to 1450 °C, for Ru, Mn and 1550 °C in the case of Cr based Y/1222, for a time duration of three hours for all the samples. All the samples crystallized with tetragonal structure in I4/mmm space group. Few minor impurities are also seen in the case of Mn,Cr/Y-1222 samples. DC magnetic susceptibility measurements exhibited ferromagnetic like transition for all the three compounds at low temperatures. At 5 K, the magnetization M(H) experiments showed clear ferromagnetic like hysteresis loops for Ru and Mn samples with sizeable returning moment (Mr) and coercive field (Hc). In the case of Cr/Y-1222 system though, ferromagnetism is visible below around 45 K in susceptibility measurements, the characteristic Mr and Hc are not seen. To the best of our knowledge the Mn,Cr/Y1222 phases are synthesized for the first time and the quality of our earlier reported Ru/Y-1222 is improved. © 2006 Elsevier B.V. All rights reserved. PACS: 74.72. Jt; 74.25. Ha; 74.25. Bt; 75.80. +q