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Seminarium ISQI - Dr Ľubomíra Regeciová

Study of spin-electron models on the Shastry-Sutherland lattice

Speaker: Dr. Ľubomíra Regeciová (Institute of Experimental Physics Slovak Academy of Sciences, Košice, Slovakia)
Date, Time: 25.04, 15:00 - 16:00

In recent research, we have introduced new models, namely the complex spin-electron model and the effective Coupled double-Ising model, to characterize the magnetization properties and thermodynamics of rare earth tetraborides (RB4). These models, unlike their predecessors, consider the different spin sizes within the spin and electron subsystems, the Hubbard interaction, and the interactions between these subsystems. Our numerical simulations showed that the integration of these factors plays a significant role in explaining the absence of a 1/3 magnetization plateau (observed in the Ising model and several of its extensions) and the stabilization of a single 1/2 plateau as observed in the TmB4 and ErB4 magnetization curves. Furthermore, there was excellent agreement between our theoretical predictions and experimental measurements of the temperature dependence of the heat capacity. Specifically, a low-temperature maximum corresponding to the electron subsystem was identified, followed by a subsequent maximum associated with the spin subsystem. In addition, our models successfully captured the cooling and heating regions in the case of the magnetocaloric effect. Another advantage of these models is their versatility, as they can be adapted by parameter optimization to describe various other metal magnets.