Multiferroic single crystals with layered structure in Pb-Mn-Ni-Ti-O system – growth and investigation of their properties

Single crystals in the prospective multiferroic mixed valence ((Mn3+/Mn4+) novel system Pb-Mn-Ni-Ti-O have been grown from high temperature solution. The new material is having a pronounced layered structure, which gives rise to strong anisotropy on its properties. The temperature and frequency dependences of dielectric properties have been investigated. The loss tangent’ abnormal behavior between 180 and 220K along with the measured complex impedance indicate relaxation process, attributed to small polaron hopping. Temperature dependent transport measurements have been performed and the thermal activation energy has been estimated. The multiferroic system Pb3(Mn7-x-yNix,Tiy)O15 have a sophisticated magnetic nature, which has been investigated by means of DC magnetization and linear and non-linear (harmonic) AC magnetic susceptibility. There is a strong anisotropy effect on the magnetic properties and complex evolution from paramagnetic, short-range antiferromagnetic state, followed by global AF ordering at 48K and some indications for spin canted effects and spin reorientation transitions at lower temperatures. The high magnetic field experiments reveal a metamagnetic behavior.