Search

Results of fundamental and third order ac susceptibility measurements in a Ni49Mn29Ga22 single crystal demonstrate that higher harmonics of ac-susceptibility measurement is an excellent tool to identify transitions/anomalies originating from different magnetic substructures that remain undetected by usual dc susceptibility measurements. Anomaly observed at low temperature (∼150 K) has also been explored by differential scanning calorimetry, temperature dependent x-ray diffraction, and transmission electron microscopy measurements. The results demonstrate that the magnetic subsystem in Ni-Mn-Ga is unstable at low temperatures not only for metastable modulated crystal structure but also for very stable nonmodulated tetragonal structure. [ABSTRACT FROM AUTHOR]

We have studied the magnetic behavior of YMn 1− x Fe x O 3 ( x =0 and 0.2) nanoparticles synthesized by conventional solid state reaction method. The as-synthesized nanoparticles were found to have hexagonal phase with P6 3 cm space group confirmed by X-Ray diffraction. The particle size was found to be ~70 nm as confirmed by both X-Ray diffraction and Transmission Electron Microscopy. DC magnetization and memory effect measurements imply that the h-YMnO 3 nanoparticles bear a resemblance to super spin-glass state following de Almeida–Thouless like behavior which is being suppressed by Fe-doping. The Fe-doping in YMnO 3 enhances the antiferromagnetic (AFM) transition temperature T N to ~79 K and induces a new magnetic state due to the surface spins which is realized as diluted antiferromagnet in a field (DAFF) as explored by the thermoremanent and isothermoremanent magnetization measured with different applied magnetic field. [ABSTRACT FROM AUTHOR]

Epitaxial thin films of double perovskite Nd 2 NiMnO 6 (NNMO) have been successfully grown on (001) oriented substrates of (LaAlO 3 ) 0.3 -(Sr 2 AlTaO 6 ) 0.7 (LSAT), SrTiO 3 (STO) and LaAlO 3 (LAO) by pulsed laser deposition under optimum growth conditions. X-Ray diffraction and reciprocal space maps of the asymmetric (103) peak reveal that the films deposited on LSAT and STO substrates are fully relaxed, while a large in- plane compressive strain has been observed in film grown on LAO. This results into the coexistence of anti-site disorder and orthorhombic phase in the film deposited on LAO, which is further confirmed from observed shift and broadening in the antisymmetric vibrations in the Raman spectra. The temperature dependent magnetization shows a ferromagnetic transition close to 200 K in all the three samples. However, film grown on LAO substrate shows an additional upturn transition at ~ 96 K ( T ′), which could be ascribed to the formation of antisite disorders further responsible for reduction of saturation magnetization (~ 1.8 × 10 5 A/m) in hysteresis curve of the sample. The ordered structure obtained on LSAT and STO exhibit in-plane easy axis with a large coercivity of ~ 0.2 T, while, the film deposited on LAO does not show any preferred anisotropic direction. [ABSTRACT FROM AUTHOR]