Crystal structure, Magnetic Structure and Magnetic Properties of (Nd, Na)-Mn-O and (Nd, K)-Mn-O based Manganites

Colossal magnetoresistive oxides, one of the amazing classes of materials have been the subject of interest for more than a decade due to their fascinating electrical and magnetic properties and, their potential applications in spintronics devices and magnetic storage. In the present work, the crystal structure, magnetic structure and magnetic properties of monovalent (K and Na) doped Nd-based manganites were studied extensively by using neutron powder diffraction, x-ray diffraction techniques and magnetizations measurements. 
The Na-doped samples exhibit paramagnetic (PM) to ferromagnetic (FM) transition followed by spin-glass (SG) like transitions, spin canting, charge-ordering (CO), and field induced metamagnetic transitions. The magnetic ordering is found to undergo a transition from A-type antiferromagnetic (AFM) structure for x = 0 to pseudo CE-type AFM phase for x = 0.20 through the spin canted ferromagnetic (FM) phase for x = 0.15. The CO state in Nd0.8Na0.2MnO3 could be suppressed by tuning the particle size down to nano-metric scale and independently by applying magnetic field up to 10 T. 
In K-doped series, important properties like PM to FM transition, and spin-glass like behavior were observed. They were studied by measuring magnetization, thermoremanent magnetization, linear and non linear non-linear ac susceptibility. The critical exponent behavior was studied by measuring isothermal magnetization in the vicinity of transition temperature. The magnetic structure of the materials was studied by recording neutron powder diffraction patterns. The above results would be presented in seminar.