Iron nitride thin films have potential applications in the biomedicine andenergy. The magnetic properties of these films can be tuned by incorporatingcopper nitride. In this study, iron copper nitride thin films have beenfabricated by magnetron sputtering technique either by co-sputtering ironnitride and copper nitride or by layer stacking of the materials. The structure,morphology and magnetic properties of the films have been studied by scanningelectron microscopy, x-ray diffraction, x-ray reflectivity and vibrating samplemagnetometry.

The performance of a novel type of NdFeB micromagnets fabricated by agglomerationof magnetic powder by atomic layer deposition is investigated. The ALD-bondedmicromagnets can withstand standard BEOL (back-end of line) processing and heattreatments at temperatures of up to 400 °C in air and vacuum withoutany significant impact on the demagnetization curves. By optimized packingdensity a remanence of 660 mT is realized for the micromagnets. The coercivityµ0Hc = 890 mT remains constant forall samples and corresponds to the powder value.

A comparison of the demagnetizing behavior of micromagnets with theory of solidbody magnets prove that the influence of particle shape and hollow spaces ondemagnetizing field is low. Hence, a similar impact of shape on stray field andforces as for solid body magnets can be assumed when integrating NdFeBALD-bonded micromagnets in applications.

Nanoparticle system with the compositionxEu2O3-(1-x)α-Fe2O3 (x= 0.1 and 0.5) was successfully synthesized by mechanochemicalactivation of Eu2O3 andα-Fe2O3 mixtures for 0-12 hours of ball millingtime. The study is of relevance to catalysis, biomedical, sensing andenergy-related applications. 57Fe and 151EuMössbauer spectroscopy were used to investigate the phase evolution,solid solution formation and hyperfine parameters ofxEu2O3-(1-x)α-Fe2O3nanoparticle system under the mechanochemical activation process. The57Fe Mössbauer studies showed that the spectrum of the ballmilled samples evolved from a sextet for hematite to sextets and a doublet uponduration of the milling process with europium oxide. This indicated theformation of the EuFeO3 perovskite for large x values and longmilling times. The 151Eu Mössbauer investigations showedthat the isomer shift decreased with increasing milling time for all molarconcentrations employed.

Graphite-doped hematite and magnetite nanoparticles systems (∼50 nm)were prepared by mechanochemical activation for milling times ranging from 2 to12 hours. Their structural and magnetic properties were studied by57Fe Mössbauer spectroscopy. The spectra corresponding tothe hematite milled samples were analyzed by considering two sextets,corresponding to the incorporation of carbon atoms into the iron oxidestructure. For ball milling time of 12 hours a quadrupole split doublet has beenadded, representing the contribution of ultrafine particles. TheMössbauer spectra of graphite-doped magnetite were resolved consideringa sextet and a magnetic hyperfine field distribution, corresponding to thetetrahedral and octahedral sublattices of magnetite, respectively. A quadrupolesplit doublet was incorporated in the fitting of the 12-hour milled sample. Therecoilless fraction for all samples was determined using our previouslydeveloped dual absorber method. It was found that the recoilless fraction of thegraphite-doped hematite nanoparticles decreases as function of ball millingtime. The f factor of graphite-containing magnetitenanoparticles for the tetrahedral sites stays constant, while that of theoctahedral sublattice decreases as function of ball milling time. These findingsreinforce the idea that carbon atoms exhibit preference for the octahedral sitesof magnetite.

Mn-Ga alloys have shown promising hard magnetic properties, even though thesealloys contain no rare-earth metals. However, much work is needed before Mn-Gaalloys become viable permanent magnets for applications. One of the challengesis to enhance the remanence. One technique to improve this property is applyinga magnetic field during the heat treatment process. Magnetic annealing canpromote phase transformation of the phases with high magnetic moment. Thisresults in an increased remanence. Bulk samples of Mn-Ga alloys were made bymechanically alloying in order to create a nanostructured composite, followed byheat treatments in the presence of a 31 T magnetic field. The heat treatmenttemperatures were kept low in order to keep the refined microstructure. All thealloys exhibit hard magnetic properties at room temperature with largecoercivity. This work reports findings of magnetic field annealed Mn-Ga bulkthat exhibit high coercivities up to 19.4 kOe and increased remanence of 50%over the binary system, achieving values up to 6.9 emu/g. This is the highestcoercivity reported in bulk Mn-Ga samples.

The crystal structure and phase transformations of iron sulfide nanomaterialshave interesting properties that can be utilized in solar cells, biological andother applications. Iron (III) complexes piperidine (1) andtetrahydroquinoline (2) dithiocarbamate have been synthesized andsubsequently utilized as single source precursors for the preparation of ironsulfide nanoparticles by solvothermal and pyrolysis methods. The powder X-raydiffraction (p-XRD) studies gave crystalline information of the iron sulfidenanoparticles which were dependent on the reaction conditions. Only the greigitephase (Fe3S4) was obtained when the solvothermal methodwas used during the synthesis. The pyrolysis method gave a mixture of pyrite(FeS2) and pyrrhotite phases when complex (1) wasused while complex (2) gave pure pyrrhotite. Well interconnectedmicrostructures and nanoflakes-like structures were obtained by scanningelectron microscopy imaging. Furthermore, magnetic properties of theas-synthesized nanoparticles displayed ferromagnetic and antiferromagneticbehaviour, typical of greigite and pyrrhotite nanoparticles respectively. Adirect band gap of 2.70 eV was obtained according to optical absorptionstudies.

We conducted the in-situ observations of the magnetic domain structure change inNd-Fe-B magnets at high temperature by transmission electron microscopy (TEM) /Lorentz microscopy with applying an external magnetic field. Prior toobservation, a thin foil was magnetized by an external magnetic field of 2.0 Tto almost saturation, then the magnetic domain structures were observed by theFresnel mode with in-situ heating. At 225°C, reverse magnetic domainswere found to generate in the thin foil sample without applying an externalmagnetic field. When we applied a magnetic field on the same direction to thepre-magnetization direction at 225°C, one magnetic domain wall waspinned by a grain boundary and the other magnetic domain wall moved. As theresults, the reverse magnetic domain shrank then annihilated. When we cut theapplied magnetic field, the reverse magnetic domain generated at almost the samelocation. On the other hand, when we applied a magnetic field to the foils inthe opposite direction, the reverse domain started to grow, i.e., magneticdomain walls started to move. The observation results of the shrink or growth ofthe reverse domain showed that the pinning effect of grain boundary againstdomain wall motion would be different depending on the applied magnetic fielddirection. Moreover, domain walls was observed to be pinned by grain boundariesat elevated temperature, so that the coercivity of Nd-Fe-B magnet would occur bypinning mechanism.

Magnetic hyperthermia is a non-invasive cancer treatment method which is usedsynergistically with the current cancer treatments. Improved biocompatibilityand enhanced heating characteristics are the pressing challenges to be addressedin magnetic hyperthermia. Through a novel combinatorial approach, we haveattempted to address both the challenges. Ferrimagneticmagnetite nanoparticles(FMNPs)of size 50 nm were synthesized by thermal decomposition method and wereconverted to hydrophilic phase by 3-Aminopropyltrimethoxysilane (APTMS). SerumAlbumin (SA) from rat was conjugated over the APTMS-FMNPs to convert tobiocompatible phase. The preliminary haemolysis experiments show that SA-FMNPsare non-haemolytic (1.2 % haemolysis). It is observed from the magnetic heatingexperiments that due to better colloidal stability, the Specific Absorption Ratevalue of the SA-FMNPs are higher (2100 W/g) than the FMNPs without SA (1400W/g). Thus we report here that SA conjugation over FMNPs (with a high saturationmagnetization of 75 emu/g) provides a novel combinatorial approach to enhanceboth the biocompatibility and the SAR value for magnetic hyperthermia.