Magnetic, electrical, and small-angle neutron-scattering studies of possible long-range order in the pyrochlores Tl2Mn2O7 and In2Mn2O7

Tl2Mn2O7 and In2Mn2O7 show spontaneous magnetization around 121 K indicating magnetic phase transitions. The related pyrochlores Y2Mn2O7 and Lu2Mn2O7 also exhibit spontaneous magnetization at their respective magnetic transition temperatures around 17 K. However, neutron-scattering studies do not provide any evidence for long-range order but suggest reentrant spin-glass behavior. In view of this we have performed small-angle neutron-scattering …