Magnetic, Electrical and Structural Research

magelestr
Our group and collaborators:
M.Ziarek, J.Niewolski, A.Żywczak, Ł.Gondek
K.Koźlak, N.B.Selvaraj, M.Ornat
A.Paja, Prof. W.Sikora (Dept. Cond. Matt. Phys), H.Figiel

    Staff scientists

  • Dr hab. Antoni Paja,
    - prof. of the AGH-UST
    - Head of the group
  • Prof. dr hab. Henryk Figiel
  • Dr. Łukasz Gondek
  • Dr. Eng. Janusz Niewolski

    PhD Students

  • MSc. Nivas Babu Selvaraj
  • MSc. Eng. Kamil Koźlak
  • MSc. Eng.  Maurycy Ornat
  • MSc. Eng. Marcin Ziarek
  • MSc. Eng. Antoni Żywczak

International collaboration

Grants

Recent publications

Our group is involved in two main research subjects:

  • Magnetic and structural properties of intermetallic compounds and their hydrides

    The research in this field has been developed for many years by prof. H. Figiel with his coworkers. Practically all staff members are involved in this activity. Very fruitful research on REMn2Hx hydrides performed in our group in recent years gave new valuable information on their structure, specific heat, magnetic properties and phase transformations (see our list of publications and chapter V “Magnetism of Hydrides” by G. Wiesinger and G. Hilscher in: Handbook of Magnetic Materials, Vol 17, Ed. Elsevier B. V. 2008). Recently in collaboration with prof. W Sikora from the Department of Condensed Matter Physics we were able to predict the types of new structures following phase transformations induced by hydrogen using the symmetry theory of crystal structures. Further research of this type of hydrides is continued also in cooperation with dr. A. Budziak from the Institute of Nuclear Physics in Kraków. In frames of CMA EU research network we investigated whether the complex intermetallic alloys (Co4Al13, MnAl4, Al91Mn38Pd5) could absorb hydrogen and we have found that in spite of much interstitial space the investigated CMA alloys do not absorb hydrogen due to their specific electronic structure. This year we started research of the family of ternary alloys RENi5Sn (RE - Rare Earth) which absorb hydrogen. In collaboration with the group of prof. A. Takasaki from Shibaura Institute of Technology in Japan we started investigations of nano-intermetallic compounds of Ti45Zr38Ni17-xMx (M = Fe, Co, Mn) type, where we substitute Ni by Fe, Co, Cu and Mn. In parallel, involved in the EU training project HYTRAIN, we started research of medium size hydrogen storage tanks filled with metallic hydrides. The project is in progress in collaboration with University of Besancon (France). The aim of this work is to optimize construction and investigate tank thermodynamic behavior during hydrogen absorption and desorption in the tank.
    Simultaneously, we focused our interest on new intermetallic compounds. Namely, R3T4X4 and R5T2X3 ternary intermetallic compounds are being studied to get understanding of their magnetic properties. These research including structural, specific heat and electrical transport studies as well as neutron diffraction (elastic and inelastic) measurements are coordinated by dr. Gondek (see list of our publications). The above mentioned compounds exhibit unusual and complex magnetic properties as the magnetic rare earth atoms are placed at different crystal position. Thus, competition between different magnetic sublattices leads to complicated phase transitions sequences. From applicative point of view, these materials may be considered as cooling materials (at low temperatures) thanks to magnetocaloric effect. Apart from the above mentioned compounds, some families of RTX and RT2X2 are of our interest as well. RTX hexagonal compounds are particularly interesting as they exhibit spin frustration within a kagome-like rare earth ions lattice. The possible magnetic orderings were studied by means of Monte-Carlo studies.

  • Electron transport in disordered materials

    The research in this subject is carried out by prof. A. Paja accompanied by M. Ornat, PhD student and in collaboration with dr. B. J Spisak and dr. M. Wołoszyn from the Department of Applied Informatics and Computational Physics. We are doing the theoretical research of the electron transport properties (mainly resistivity and magnetoresistivity) of amorphous alloys, liquid metals and metallic nanosystems. In our calculations of electron transport properties we use the Faber-Ziman (FZ) model and the Morgan-Howson-Saub (MHS) model which is more advanced one. We calculated the resistivity of amorphous alloys within the MHS model as a function of temperature, magnetic field and the strength of the spin-orbit scattering. We also obtained the resistivity of some liquid alloys within this model in good agreement with experiment. We also calculated the resistivity of some nanostructures (ultra-thin films and nanowires) which contained magnetic impurities located at random. We obtained the dependence of the resistivity of such systems on the orientation of impurities.

Equipment

  • X-ray diffractometer type Siemens D-5000 equipped with low temperature (down to 4.2 K) cryostat.
  • System for hydriding ( Sievert type), pressures up to 500 bar, temperatures up to 300 oC
  • Research team members are trained and have access to neutron sources - BENSC Berlin, ILL Grenoble, PSI Villingen.