  We show a topological spin texture called "bimeronium" in magnets with
in-plane magnetization. It is a topological counterpart of skyrmionium in
perpendicularly magnetized magnets and can be seen as a combination of two
bimerons with opposite topological charges. We report the static structure and
spin-orbit-torque-induced dynamics of an isolated bimeronium in a magnetic
monolayer with frustrated exchange interactions. We study the anisotropy and
magnetic field dependences of a static bimeronium. We also explore the
bimeronium dynamics driven by the damping-like spin-orbit torque. We find that
the bimeronium shows steady rotation when the spin polarization direction is
parallel to the easy axis. Moreover, we demonstrate the annihilation of the
bimeronium when the spin polarization direction is perpendicular to the easy
axis. Our results are useful for understanding fundamental properties of
bimeronium structures and may offer an approach to build bimeronium-based
spintronic devices.
