Dr Zbigniew Stadnik discusses research from the Department of Physics: condensed-matter research group at the University of Ottawa
Our condensed-matter research group focuses on designing, discovering, and characterizing novel compounds (quasicrystals and their approximants, superconductors, spin glasses, and others). Their electronic, magnetic, hyperfine-interaction, and transport properties are studied with various experimental techniques. Among these techniques, Mössbauer spectroscopy plays the most prominent role. First-principles calculations supplement these experimental studies.
![155Gd Mössbauer spectra of the icosahedral quasicrystal Al50In36Gd14 at selected temperatures [Z.M. Stadnik, K. Al-Qadi, and P. Wang, J. Phys.: Condens. Matter 19, 326208 (2007)].](https://www.openaccessgovernment.org/wp-content/uploads/2022/06/Picture1.png)
In addition to two well-known forms of compounds, crystalline and amorphous, the third form was discovered in 1984. These new compounds are characterized by a novel long-range translational order called quasiperiodicity. Correspondingly, they are called quasicrystals. We attempt to determine whether quasiperiodicity leads to novel physical properties found neither in crystalline nor amorphous compounds. We also search for quasicrystals with yet to be discovered long-range magnetic order.
Approximants to quasicrystals are complex crystalline compounds closely related to quasicrystals. Studies of approximants can lead to the discovery of new quasicrystals and the elucidation of the structure and physical properties of the corresponding quasicrystals.
Superconductors are compounds that conduct electricity with zero electrical resistance below their critical temperature. We are interested in studying whether the two antagonistic phenomena, superconductivity and magnetism, can coexist in recently discovered Fe-based superconductors.
A spin glass is a magnetic state of the compound with inherent randomness, besides cooperative behaviour in freezing spins at a temperature called freezing temperature. The individual atomic bonds in a spin glass lead to so-called frustrated interactions. We are interested in the time dependence of various physical quantities of a spin glass. The time dependence of specific physical quantities seems to indicate, for example, that the nature of a spin-glass state in quasicrystals is different from that of a canonical spin glass.
