Conveners
Section S1: Theoretical challenges in magnetically ordered and disordered systems
- Jan Rusz (Department of Physics and Astronomy, Uppsala University)
Since the 1930s, magnetism has been classified into two main branches: ferromagnetism and antiferromagnetism. Recently, we have identified a third fundamental branch: altermagnetism (see Figure). Altermagnetism exhibits a compensated d-, g-, or i-wave alternating spin order and is found in a wide range of materials, from metals to insulators [1]. This discovery emerged from our systematic...
A new differential isotropic model of ferromagnetic hysteresis (DIMFH) [1] has been developed, which has removed the contradictions and ambiguities in the original Jiles-Atherton (J-A) model. This model is simpler, uses only 4 parameters ($M_s$, $a$, $h$, $β$) with clear physical meaning and is based on a new assumption: the existence of so-called magnetic clusters - a coherent regions of...
The spin-$1/2$ Ising-Heisenberg model on the extended Lieb lattice in a magnetic field is solved using a combination of analytical and numerical methods. The decoration-iteration transformation [1] maps this model onto a spin-$1/2$ Ising model on the square lattice in an effective field, which can be solved exactly provided that the effective field becomes zero. Classical Monte Carlo...
We investigate a paradigmatic model of a frustrated spin system - the sawtooth chain with magnetoelectric coupling - realized through the Katsura-Nagaosa-Balatsky (KNB) mechanism. While an applied magnetic field influences the spin system via the conventional Zeeman term, the electric field couples to the spins through the KNB mechanism, effectively manifesting as a Dzyaloshinskii-Moriya...
The emerging field of altermagnetism combines the merits of both ferromagnets and antiferromagnets, which, until recently, were thought to be incompatible. Consequently, altermagnets exhibit phenomena unmatched by either of these two traditional magnetic phases [1]. Despite the tremendous interest in this novel magnetic phase, the possible relation of altermagnetism to topology has been...
The Mermin-Wagner theorem states that in a two-dimensional $XY$ (or planar rotator) model with nearest-neighbor interactions the continuous symmetry cannot be broken and thus no standard phase transition can occur. Nevertheless, the model is well known to show a so-called Berezinskii-Kosterlitz-Thouless (BKT) phase transition due to the presence of topological excitations, called vortices and...
