Keywords:

intermetallic compounds, amorphous materials, nanocrystalline alloys, magnetism, magnetocaloric effect, thermoelectric power, Kondo lattices

The Laboratory is engaged in the complex studies of new magnetic materials such as:

• rare earth intermetallic compounds
• strongly correlated electron systems
• nanocrystalline magnetic alloys
• amorphous magnetic ribbons
• thin films of rare earth and transition metals
• metallic multilayers
• rare earth manganite
• magnetic nanostructures

Research aims

Experimental studies supported by the theoretical interpretation in the area of the strongly correlated electron systems with main emphasis on the Kondo lattices, systems with the impurity Kondo effect, fluctuating valence systems, spin glasses. Characterization of the glass forming ability of the amorphous alloys and the studies of the crystallization processes in the structurally metastable alloys. Search for new magnetocaloric and thermoelectric materials with parameters expected in applications.

Research profile

Preparation of the rare earth-based intermetallic compounds and alloys in a crystalline, nanocrystalline and amorphous form. Structural characterization (X-ray diffraction) and determination of the magnetic (magnetometry, dc and ac magnetic susceptibility), electrical (electrical resistivity, magnetoresistance, Hall effect), and thermal (specific heat, thermal conductivity, thermoelectric power) properties in a wide temperature range.

Scientific achievements

• A jump of material density was observed when changing the stoichiometry for Hf₁Cr₁Co₁₁B and Hf_0.5Cr_1.5Co₁₁B, which was correlated with a change of structure from amorphous to crystalline. Measurements have been carried out with a novel method, employing a confocal microscope, enabling measurements for samples with small volume [Śniadecki et al. Materials Characterization 132, 46 (2017)]
• Based on the measurements of the DC and AC magnetic susceptibility the magnetic phase diagram was determined for the series Ce(Cu_1-xNi_x)₄Mn. It shows a complex character, e.g. it indicates presence of regions with coexisting ferromagnetic and spin glass phases [K. Synoradzki, T. Toliński, Materials Chemistry and Physics, 177, 242-249 (2016)]
• Coexistence of two phases of Hf₂Co₁₁ was confirmed based on the XRD and thermomagnetic measurements of the alloy Hf₂Co₁₁B [A. Musiał et al. J. Alloys Compd. 665, 93 (2016)]
• The influence of the chemical and topological disorder on the magnetic properties of compounds based on the Pauli paramagnet YCo₂ has been observed and described [Z. Śniadecki et al., J. Appl. Phys. 115, 17E129 (2014), Z. Śniadecki et al., Appl. Phys. A 118, 1273 (2015), A. Wiśniewski et al., J. Alloys Compd. 618, 258 (2015)]
• Using semi-empirical models the glass forming ability of the transition metal based ternary systems has been determined. The ranges of stoichiometry promoting the alloys amorphization have been calculated [Z. Śniadecki, J. Alloys Compd. 615, S40 (2014)]
• Magnetic properties and parameters characterizing the magnetocaloric effect have been determined for ferrimagnets composed of two sublattices based on cobalt and rare earth element [Z. Śniadecki et al., J. Alloys Compd. 584, 477 (2014)]
• The mechanism of the amorphization of the alloys Y(Ce)-Cu-Al has been explained and the influence of the 4f electrons on the magnetic, transport, and thermal properties of these alloys has been described [B. Idzikowski et al., J. Non-Cryst. Solids 357, 3717 (2011), B. Idzikowski et al., J. Non-Cryst. Solids 383, 2 (2014)]
• For many cerium based compounds the influence of the crystal electric field on their physical properties has been determined. The research includes mainly the magnetic susceptibility, specific heat, and inelastic neutron scattering measurements [ Toliński et al., J. Magn. Magn. Mater. 345, 243 (2013)]
• For the first time the adiabatic temperature change and the influence of the grains size on the efficiency of the magnetocaloric effect in the Mn₅Ge₃ compound have been determined. For selected compounds of the series RNi₄M (R- rare earth, M - metalloid) the parameters characterizing the magnetocaloric effect have been extracted. [T. Toliński et al., Intermetallics 47, 1 (2014), Toliński et al., J. Alloys Compd. 523, 43 (2012)]
• Complementary studies of the isostructural series of compounds Ce(Cu_1-xNi_x)₄Mn_yAl_1-y enabled a construction of magnetic phase diagrams for four transformations between different ground states (ferromagnetic state, spin glass, fluctuating valence, heavy fermions) [K. Synoradzki et al., Phys.: Condens. Matter 24, 136003 (2012)]
• Magnetic susceptibility measurements in a wide temperature range (2-1000 K) supported by the interconfiguration fluctuation model (ICF) have shown a presence of the valence fluctuations between Yb³⁺ and Yb²⁺ for the compound YbNiAl This compound is not a heavy fermion system, which results from the determined small value of the electronic specific heat coefficient. [A. Kowalczyk et al., J. Appl. Phys. 107, 123917 (2010)]
• The temperature dependences of the thermopower have been determined and explained for the Kondo lattices CeCu₄M and for compounds exhibiting fluctuating valence CeNi₄M (M = In, Ga) [T. Toliński et al., J. Alloys Compd. 490, 15 (2010)]
• Apart from the experimental methods employed directly in the Magnetic Alloys Department, the carried out researches involve many complementary methods accessible in frames of the international cooperation (neutron diffraction, inelastic neutron scattering, synchrotron radiation)