The magnetic ground states in highly ordered double perovskites LaSr_1−xCa_xNiReO₆ (x = 0.0, 0.5, 1.0) are studied in view of the Goodenough-Kanamori rules of superexchange interactions in this paper. In LaSrNiReO₆, Ni and Re sublattices are found to exhibit curious magnetic states separately, but no long range magnetic ordering is achieved. The magnetic transition at ~255 K is identified with the independent Re sublattice magnetic ordering. Interestingly, the sublattice interactions are tuned by modifying the Ni-O-Re bond angles through Ca doping. Upon Ca doping, the Ni and Re sublattices start to display a ferrimagnetically ordered state at low temperature. The neutron powder diffraction data reveals long range ferrimagnetic ordering of the Ni and Re magnetic sublattices along the crystallographic b-axis. The transition temperature of the ferrimagnetic phase increases monotonically with increasing Ca concentration.

The structural, magnetic and dielectric properties of the hexagonal four-layered form of SrMnO ₃ along with its fluorinated counterpart have been investigated.

Perovskites containing barium metal at the $A$ site often take up unusual hexagonal structures having more than one type of possible sites for the $B$ cation to occupy. This opens up various different $B\text{−}B$- or $B$-O-$B$-type connectivities and consequent physical properties which are naturally missing in cubic perovskites. ${\mathrm{BaRuO}}_3$ is one such system where doping of Ru $\left(4d^4\right)$ by other transition metals $\left(M^{n+}\right)$ creates similar conditions, giving rise to various $M$-Ru interactions. Interestingly, the $6H$ hexagonal structure of doped barium ruthenate triple perovskite $\left({\mathrm{Ba}}_{3}M{\mathrm{Ru}}_2{\mathrm{O}}_9\right)$ seems to possess some internal checks because within the structure $M$ ion always occupies the $2a$ site and Ru goes to the $4f$ site, allowing only $M$-O-Ru ${180}^{\circ }$ and Ru-O-Ru ${90}^{\circ }$ interactions to occur. The only exception is observed in the case of the Fe dopant, which allows us to study almost the full ${\mathrm{Ba}}_3{\mathrm{Fe}}_{1-x}{\mathrm{Ru}}_{2+x}{\mathrm{O}}_9$ series of compounds with wide ranges of $x$ because here Fe ions have the ability to freely go to the $4f$ sites and Ru readily takes up the $2a$ positions. Therefore, here one has the opportunity to probe the evolution of electronic and magnetic properties as a function of doping by going from ${\mathrm{BaRuO}}_3$ (paramagnetic metal) to ${\mathrm{BaFeO}}_3$ (ferromagnetic insulator). Our detailed experimental and theoretical results show that the series does exhibit a percolative metal-insulator transition with an accompanying but not coincidental magnetic transition as a function of $x$.

The present review places emphasis on a comprehensive survey of experimental techniques to probe the structural and morphological features at the nanoscale range in thin magnetic films, incorporating those available at in-house laboratories as well as those at state-of-the-art synchrotron radiation facilities. This elucidating the range of available techniques, and the information they can yield represents a step for advancing the understanding of and for unlocking new possibilities in the design and optimization of thin magnetic films across a wide range of applications.