Speaker
Description
Geometrically frustrated lattices play an important role in emergent quantum mechanical
phases, which have been rather well investigated in electronic insulators. A system that
exhibits both lattice frustration and metallic behaviour are the rare-earth (RE) tetraborides
REB 4 . They have a tetragonal structure with magnetic RE ions embedded in boron network
and forming a lattice topologically equivalent to the frustrated Shastry-Sutherland lattice with
the strong Ising single-ion anisotropy.
In our contribution we compare the behaviour of TmB 4 and ErB 4 by investigating the angular
dependencies of their thermal and magnetic properties in a wide range of temperatures (T) and
magnetic fields (H) as well as transport properties under pressure up to 3 GPa. Compared are
also the rotating magneto-caloric effects (R-MCE) of both compounds. Spin-electron model
was suggested to explain the complex behaviour of R-MCE, which is based on the idea of two
interacting systems: the localized spins of RE ions and the itinerant electrons in conduction
band. The received results from Monte Carlo approach successfully reproduce the observed
heating and cooling regions in H - T phase diagrams of TmB 4 . Thus, our study shows that
measurements of R-MCE can be an effective tool for investigating the microscopic properties
of magnetization processes.
