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The ABO 3 type manganites ͑LaR͒ 0.45 ͑CaSr͒ 0.55 MnO 3 ͑R=Eu 3+ -a nonmagnetic ion and Tb 3+ -a magnetic ion͒ which possess large A-site size-disorder, exhibit metamagnetic transitions as a function of magnetic field. Below a certain crossover temperature and depending on the magnetic field sweep rate, the metamagnetic transition transforms from a broad to sharp step-like transitions. This crossover temperature increases on increasing the field sweep rate. The effect of field sweep rate on the critical field of metamagnetic steps decreases with decreasing temperature. This along with the magnetic relaxation and specific heat data provide clear evidence on the contribution of spin-lattice coupling in determining the transformation from smooth to sharp magnetic transitions. These studies also suggest that the A-site magnetism has no important role in transformation from reversible to irreversible magnetization.

We investigate the resistive switching behavior of Ba-doped BiFeO3 (BBFO) films grown on single crystalline SrTi0.99Nb0.01O3 substrates. Observation of diode like I-V behavior and reduction in VC with Ba-content in BBFO films have been understood in the context of modifications in its energy band diagram. Also, I-V curves exhibit hysteresis which has been explained on the basis of migration and recombination of oxygen vacancies under field conditions. Furthermore, increment in Ba-content improves the retention property and ON/OFF switching ratio in BFO films which makes them suitable for applications in switching devices.

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The structural and superconducting properties of ( samples have been studied by x-ray diffraction, resistivity, a.c. susceptibility and oxygen content measurements. The effect of increasing La concentration in is in lowering the carrier concentration and decreasing , which is attributed to hole filling by La. This suppression of has been compensated by appropriate hole doping with Ca in (, which shows that for a fixed La content increases dramatically as the Ca content increases. For instance, in the oxide (, the increases from 35 K (x = 0.0) to 82 K (x = 0.4, compensated oxide) as the hole filling by La is completely balanced by hole doping form Ca.