The effect of stress on the magnetic properties of low bandwidth manganites

The low bandwidth Pr0.9Ca0.1MnO3 (PCMO) thin films prepared by sol-gel method were suffered tensile and compressive stress grown on SrTiO3 and LaAlO3 substrates. The hysteresis loops at different temperatures show that the coercivity field with tensile stress is larger due to the much stronger pinning potential of ferromagnetism motion. The temperature dependence of the ZFC and FC magnetizations indicates that the stress significantly affects the ferromagnetic (FM) and antiferromagnetic (AFM) transition temperature of PCMO, and the Curie temperature (TC) decreases with tensile stress. The films show strong anisotropy properties that the magnetization increases much faster with the magnetic field when H⊥c, but the coercive field and saturation magnetization do not change significantly. In addition, the persistent photoinduced magnetization is investigated, and significant improvement of the ferromagnetic ordering was observed in low temperature.

Current-induced reordering phase transitions of vortex matter in 3D-layered superconductors

Nonequilibrium phase transitions of vortex matter with a strong random pinning potential in layered superconductors are investigated by the three-dimensional frustrated anisotropic XY model and resistively-shunted junction dynamics at low, middle and high-temperatures, respectively. It is found that a disorder to order phase transition driven by an external current can be obtained at a low-temperature, however, a reordering configuration does not occur at a high-temperature. With the competition between thermal noise, disorder pins and current, the vortex matter can even show the reordering process twice at an intermediate temperature, giving a clear evidence of dc driven vortex lattice reorganization.

Pinning Effect on Current-Induced Domain Wall Motion in Nanostrip

Pinning effect on current-induced magnetic transverse domain wall dynamics in nanostrip is studied for its potential application to new magnetic memory devices. In this study, we carry out a series of calculations by solving generalized Landau-Lifshitz equation involving a current spin transfer torque in one and two dimensional models. The critical current for the transverse wall depinning in nanostrip depends on the size of artificial rectangular defects on the edges of nanostrip. We show that there is intrinsic pinning potential for a defect such that the transverse wall oscillates damply around the pinning site with an intrinsic frequency if the applied current is below critical value. The amplification of the transverse wall oscillation for both displacement and maximum value of m3 is significant by applying AC current and current pulses with appropriate frequency. We show that for given pinning potential, the oscillation amplitude as a function of the frequency of the AC current behaves like a Gaussian distribution in our numerical study, which is helpful to reduce strength of current to drive the transverse wall motion.

SUPERCONDUCTING CABLES – ANALYSIS OF THEIR OPERATION AND APPLICATIONS IN ELECTRIC GRIDS

In this paper the use of high temperature superconducting cables for transporting electrical energy is analysed. The construction of a short model of a superconducting cable is explained, global progress in this field is examined and related electromagnetic phenomena are discussed, particularly those concerning pinning potential barrier formation. The paper analyses the results of investigations into the current-voltage characteristics of superconducting cable model working in the temperature of liquid nitrogen, allowing to reach the value of critical current equal to 45 A.