Crystal and magnetic structures of the high pressure RMnMnReO6 (R = La, Pr) double double perovskites

We have recently discovered a new RMnMnReO6 series of double double perovskites; they are of particular interest for magnetic properties as they contain magnetic cations at all four of the AA’BB’O6 sites (when R3+ is magnetic). The R = Nd material was discovered first and has recently been studied at WISH (RB2220431). We have synthesised two new RMnMnReO6 (R = La, Pr) materials that are proposed for study here. The magnetic susceptibilities of RMnMnReO6 (R = La, Pr) show ferrimagnetic transitions at ~135 K for R = La and at ~225 K for R = Pr, and further investigation on R = Pr using AC susceptibility clearly indicates successive magnetic transitions at 60, 160, and 225 K. Neutron diffraction is necessary to investigate the crystal and magnetic structures of these double double perovskites. With time for temperature changes and sample equilibration, as well as considering the small amounts of sample available (100 mg each, combining several batches from high-pressure synthesis), 3 days of beamtime are requested at WISH.