Nikolina Novosel

Institute of Physics, Zagreb

Among transition metal oxides, manganites have attracted significant attention because of colossal magnetoresistance (CMR)—a magnetic field-induced metal–insulator transition close to the Curie temperature. CMR is closely related to the ferromagnetic (FM) metallic phase which strongly competes with the antiferromagnetic (AFM) charge ordered (CO) ph...

Carbon distribution and grain boundary diffusion processes are studied in a variety of FeCr alloys and steels with different chromium content and microstructure, based on magnetic after‐effect measurements performed in a broad temperature range, from 100 K to 1000 K. The existence of three metastable carbon positions in the lattice is revealed in t...

In this work, we present frequency-dependent magnetic susceptibility and dc electric transport properties of three different compositions of hexaferrite Ba1−xPbxFe12−yAlyO19 single crystals. We found a correlation between the activation energies of the dc electric transport and the ac magnetic susceptibility which persists over the whole studied ra...

Magnetic dynamics of iron oxyhydroxide akaganéite nanoparticles, functional building blocks of the newest generation iron deficiency drug Ferinject, has been studied. While magnetism of the involved nanoparticles relies in general on bulk properties of akaganéite, the low temperature magnetic dynamics of Ferinject differs a lot from large number of...

In this work we present frequency-dependent magnetic susceptibility and dc electric transport properties of three different compositions of hexaferrite Ba$_{1-x}$Pb$_{x}$Fe$_{12-y}$Al$_{y}$O$_{19}$. We find a correlation between activation energies of dc electric transport and ac magnetic susceptibility which persists in the whole researched range...

TeVO 4 is a frustrated spin-1/2 zigzag chain system, where spin-density-wave (SDW), vector-chiral (VC) and an exotic dynamic spin-stripe phase compete at low temperatures. Here we use torque magnetometry to study the anisotropy of these phases in magnetic fields of up to 5 T. Our results show that the magnetic-field-induced spin reorientation occur...

\beta$-TeVO$_4$ is a frustrated spin 1/2 zig-zag chain system,where spin-density-wave (SDW), vector chiral (VC)and an exotic dynamic spin-stripe phase compete at low temperatures. Here we use torque magnetometry to study the anisotropy of these phases in magnetic fields of up to 5 T. Our results show that the magnetic-field-induced spin reorientati...

In frustrated spin-1/2 chains competition between the nearest-neighbor ferromagnetic (FM) and the next-nearest-neighbor antiferromagnetic (AFM) interactions leads to a number of complex ground states. One of the key ingredients that add to the complexity of the phase diagrams of these systems is the magnetic anisotropy which defines the details of...

We report on the electrodynamic properties of the single crystalline lead-substituted M-type barium hexaferrite, Ba _0.3 Pb _0.7 Fe _12 O _19 , performed in the broad frequency range including radio-frequency, terahertz and sub-terahertz bands, which are particularly important for the development of microelectronic devices. We demonstrate how chang...

The search for and understanding of low-dimensional magnetic materials is essential for both fundamental and technological purposes. Here we propose a combined experimental and theoretical investigation of such a system, namely the monoclinic phase of SeCuO 3. This low-dimensional spin-1 2 antiferromagnet appears to be based on two decoupled magnet...

We report on the magnetocrystalline anisotropy energy (MAE) and spin reorientation in antiferromagnetic state of spin S = 1/2 tetramer system SeCuO 3 observed in torque magnetometry measurements in magnetic fields H < 5 T and simulated using density functional calculations. We employ simple phenomenological model of spin reorientation in finite mag...

We report on the magnetocrystalline anisotropy energy (MAE) and spin reorientation in antiferromagnetic state of spin S = 1/2 tetramer system SeCuO3 observed in torque magnetometry measurements in magnetic fields H < 5 T and simulated using density functional calculations. We employ simple phenomenological model of spin reorientation in finite magn...

We report on the magnetocrystalline anisotropy energy (MAE) and spin reorientation in antiferromagnetic state of spin $S=1/2$ tetramer system SeCuO$_3$ observed in torque magnetometry measurements in magnetic fields $H<5$~T and simulated using density functional calculations. We employ simple phenomenological model of spin reorientation in finite m...

Magnesium diboride (MgB2) is a superconductor characterized by interesting properties like rather high superconducting transition temperature Tc = 39 K, long coherence length and low anisotropy. In addition, it has a very simple crystal structure and low density. Those properties make the MgB2 an ideal candidate for a wide range of applications. To...

The influence of magnetic nanoadditives (MN) on electromagnetic properties of MgB2 wires is compared with the effects of nonmagnetic nanoadditives (NN) in bulk MgB2 and with irradiation effects in HTc tapes. Both coated (carbon, silica, or dextrin shell) and uncoated MN were used in order to assess the effects of co-doping and interparticle interac...

In this study, magnetic nanoparticles (MNPs) of maghemite (gamma-Fe2O3) were synthesized and characterized. The method of multifactor experimental design and evolutionary operation (EVOP) was used to optimize immobilization of the alcohol dehydrogenase (ADH) enzyme on MNPs. Optimal operating conditions for the immobilization process were determined...

The results indicating magnetic flux pinning in MgB2 wires doped with three types of magnetic nanoparticles (MNP) are reported. The magnetic state of MNPs, both as-prepared and inside the MgB2 core, was determined with magnetization and ac susceptibility measurements. The competition between detrimental influence of doping (reduced connectivity, pa...

Multilayer thin films consisting of 10 bilayers of (Al2O3+Ni)/Al2O3 were deposited by magnetron sputtering onto Si(100) substrate. Nickel nanoparticles are formed inside amorphous alumina matrix by self-assembly growth process. It was determined by GISAXS measurements that nickel particles are spheroidal with diameter < 3 nm and that they form para...

Two samples of amorphous nanoparticles FeNiB, one of them with SiO2 sheath around the core and one without, were investigated by transmission electron microscopy and magnetic measurements. The coating gives mean particle diameters of 4.3 nm compared to 7.2 nm for the uncoated particles. Magnetic measurements prove superparamagnetic behaviour above...

NiCoB nanoparticles, as-prepared and coated by SiO2, were synthesized by chemical reduction of metallic salts. The as-prepared samples were additionally annealed at 650 for 1 hour in argon atmosphere. All samples (the as-prepared and annealed ones) were investigated by X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-...

Main results of ongoing comprehensive study of the influence of magnetic nanoparticles (MNP) on superconducting properties (transition temperature T c, critical fields and critical current density, J c, etc.) of high-quality Fe-sheathed MgB2 wires are briefly reviewed. We prepared over 60 Fe-sheathed MgB2 wires doped with 12 different types and qua...

Recently we begun systematic study of the influence of magnetic nanoparticles (MNPs) on the superconducting properties (transition temperature Tc, critical fields and critical current density, Jc) of MgB2 wires. We prepared over 60 Fe-sheathed MgB2 wires doped with different types and quantities of MNPs, such as pure metals (Fe, Co, Ni), magnetic b...

The electromagnetic properties of well-characterized iron-sheathed MgB2 wires, undoped and doped with dextrin-coated magnetite nanospheres and nanorods, have been studied in the temperature range 5–300 K and a magnetic field up to 16 T. Doping hardly affected the superconducting transition temperature and the active cross-sectional area of the wire...

A systematic study of the influence of doping MgB2 with single domain magnetic nanoparticles of NiCoB alloy, uncoated and coated with SiO2, has been performed. Electrical resistivity, transport critical current density, Jc(B,T), and magnetization of well characterized undoped and doped with 1.38 and 2.67 wt% of NiCoB particles (both uncoated and co...

The influence of CuFe2O4 nanoparticle doping on superconducting properties of Fe-sheated MgB2 wires has been studied. The wires containing 0, 3 and 7.5 wt.% of monodisperse superparamagnetic nanoparticles (similar to 7 nm) were sintered at 650 degrees C or 750 degrees C for 1 hour in the pure argon atmosphere. X-ray diffraction patterns of doped sa...

The anion radicals with nonaromatic π-systems, such as semiquinones, are interesting in the design of functional materials. Magnetic properties of solvates of alkali salts of tetrachlorosemiquinone (chloranil) radical anion are tuned by crystal engineering using different solvents (2-butanone and acetonitrile) and/or cations (potassium and ammonium...

Iron-sheathed MgB2 wires doped with 0, 1.3 and 2.52 wt% carbon protected nickel superparamagnetic nanoparticles (the average diameter of the particles is 20 nm) and sintered at 650 °C were prepared. X-ray diffraction patterns and magnetization measurements showed that neither substitution of C for B nor substitution of Ni for Mg occurred during the...

It is known that the Mn 2+ fluorescence spectrum consists of an emission band that might be found in the green or in the red of the electromagnetic spectrum according to the nearest environment. In order to control this emission in one or the other wavelength the Mn 2+ ion was introduced as a doping element in sodium halides mixtures, containing di...

The effect of processing temperature on structural and superconducting properties of 10 wt.% sugar- and 10 wt.% PCS-doped MgB2 wires is systematically investigated. It is demonstrated that these dopants significantly enhance the electromagnetic performance of Fe-clad MgB2 superconductor and increase its potential for practical application. The enha...

The effects of magnetic nanoparticle doping on superconductivity of MgB2/Fe wires have been investigated. Fe2B and SiO2-coated Fe2B particles with average diameters 80 and 150 nm, respectively, were used as dopands. MgB2 wires with different nanoparticle contents (0, 3, 7.5, 12 wt.%) were sintered at temperature 750°C. The magnetoresistivity and cr...

Nanocrystalline particles of the Fe2−xAlxCoO4 (0 ≤ x ≤ 1) ferrites with cubic spinel structure have been synthesized by the sol-gel method. Size of the particles decreases from 39 nm to 6 nm as the Al content x increases. In the present work magnetic hysteresis curves and ZFC-FC curves have been studied. The magnetization of the Fe2CoO4 nanoparticl...

Nanocrystalline particles of the Fe2-xAlxCoO4 (0

Magnetic properties of single crystals of the heterometallic complex [Cu(bpy)3]2[Cr(C2O4)3]NO3·9H2O (bpy = 2,2′-bipyridine) have been investigated. From the recorded EPR spectra, the spin-Hamiltonian parameters have been determined. The magnetization measurements have shown magnetic anisotropy at low temperatures, which has been analysed as a resul...