Monopole field textures in interacting spin systems

Abstract

Magnetic monopoles can appear as emergent structures in a wide range of physical settings, ranging from spin ice to Weyl points in semimetals. Here, a distribution of synthetic (Berry) monopoles in parameter space of a slowly changing external magnetic field is demonstrated in a system of interacting spin-$\frac{1}{2}$ particles with broken spherical symmetry. These monopoles can be found at points where the external field is nonzero. The spin-spin interaction provides a mechanism for splitting the synthetic local magnetic charges until their magnitude reach the smallest allowed value $\frac{1}{2}$. For certain states, a nonzero net charge can be created in an arbitrarily large finite region of parameter space. The monopole field textures contain non-monopolar contributions in the presence of spin-spin interaction.