Ospinon

Ospinon is a hypothetical quasiparticle in condensed matter physics, proposed as an emergent excitation in certain strongly correlated electron systems with notable spin-orbit coupling. The term merges "orbital" and "spin" to describe a neutral, itinerant excitation that carries orbital angular momentum but no net charge.

In theoretical models, ospinons arise when spin and orbital degrees of freedom are entangled, producing collective modes that can behave as independent excitations separate from conventional spinons (spin-1/2) and orbitons (orbital excitations). Ospinons are predicted to occur in insulating or Mott-like phases on lattices with strong spin-orbit interactions, such as Kitaev-like magnets or certain perovskite-derived systems. Their dispersion, symmetry, and statistics depend on lattice geometry and interaction strengths, and they may couple to phonons or magnetic textures, producing distinctive spectroscopic signatures.

Experimentally, there is no definitive observation of ospinons. Researchers seek indirect signatures in spectroscopic probes such as inelastic neutron scattering, resonant inelastic X-ray scattering, and Raman spectroscopy, aiming to separate ospinon features from those of spinons and orbitons. The unambiguous identification of ospinons remains an active area of theoretical and experimental work, with interpretations often contending with overlapping signals from other collective excitations.

Relation to other quasiparticles: ospinons differ from spinons, which carry spin without charge, and orbitons, which carry orbital excitations; ospinons couple both spin and orbital sectors and represent an additional degree of freedom in strongly correlated, spin-orbit coupled materials. Potential implications include contributions to unconventional magnetic dynamics, transport anomalies, and, if stabilized and controllable, considerations for quantum information processing and materials design in spin-orbit–rich systems.