Materials whose physical properties considerably differ as a consequence of a mild change of ambient conditions represent promising candidates for applications in recording media, sensors, and even medicine. This work focuses on the FeRh alloy which features the magnetic phase transition from the antiferromagnetic (AF) to ferromagnetic (FM) order accompanied by changes in electrical resistance and crystalline structure. Attention is paid to spatial confinement effects in submicron FeRh structures where the phase transition becomes asymmetric. FeRh micro- and nanostructures were prepared by nanolithography techniques from epitaxial FeRh films
grown by magnetron sputtering. The magnetic phase transition is probed using vibration magnetometry, X-ray diffraction for epitaxial films, as well as electrical transport measurements and magnetic imaging using magnetic force microscopy. The last two techniques demonstrate an increasing asymmetry of the phase transition that becomes typical for FeRh structures of micron and submicron dimensions. Magnetoresistance
measurements provide insight into specific AF ordering appearing in the low-temperature phase of FeRh stripes. The study proved an ability to control the AF ordering of FeRh by external magnetic fields through an exchange interaction occurring between the AF and residual FM layers. Two metamagnetic hybrid FeRh-MnRh systems are further presented
- FeRh/MnRh superlattices and Fe50-xMnxRh50 ternary alloys, in which both the transition temperature and width of temperature hysteresis can be tuned by thickness of layers and Mn concentration, respectively. This way of tuning enables specific on-demand thermal hysteresis, which can be implemented into on/off switchable spin valves and tunneling magnetoresistance devices.