Limiting long-range-ordered solids to finite sizes in condensed-matter physics

We have examined some of the consequences of finite size effects in solids which exhibit cooperative behaviour. These are materials with long-range interactions based on ferromagnetism, ferroelectricity, and superconductivity. Limiting the range of interaction is achieved by creating nanocrystals, nanodomains, disorder, high-concentration solid solutions and submicron microstructure in sintered compacts. The attempt is to elucidate underlying principles essential at a microscopic level for each of the three phenomena. Not much work has been reported in this area earlier and most of the results are from our own studies. Some of the work is reported for the first time. The experimental techniques used are Mössbauer, Raman and infrared spectroscopies, high-temperature x-ray diffraction, electron energy loss spectroscopy, dielectric and piezoelectric response, ferromagnetic resonance and spinwave dispersion, 4-probe resistivity, DC & AC magnetic susceptibilities and differential scanning calorimetry.