Exotic Spin Excitations in a Polar Magnet VOSe_{2}O_{5}

Area of Science:

• Condensed Matter Physics
• Materials Science
• Magnetism

Background:

• Polar magnets exhibit complex magnetic phases, including skyrmion lattices (SkL), which are of significant interest for fundamental research and potential applications.
• Understanding the dynamics of spin excitations in these materials is crucial for characterizing their magnetic properties and exploring novel phenomena.

Purpose of the Study:

• To investigate the magnetic resonance dynamics of the polar magnet VOSe_{2}O_{5}.
• To identify and characterize spin excitation modes in different magnetic phases, including the Néel-type skyrmion lattice (SkL).
• To elucidate the spin oscillation mechanisms through comparison with micromagnetic simulations.

Main Methods:

• Experimental study of magnetic resonance dynamics in VOSe_{2}O_{5} using oscillating magnetic fields applied parallel (B_{ν}∥c) and perpendicular (B_{ν}⊥c) to the crystallographic c-axis.
• Micromagnetic simulations to reproduce observed excitation modes, selection rules, and relative resonance frequencies.
• Analysis of spin excitation modes in various magnetic phases, including cycloidal, SkL, IC-2, and a novel B' phase.

Main Results:

• Two excitation modes active to B_{ν}⊥c and one mode active to B_{ν}∥c were identified in both cycloidal and SkL spin states.
• Micromagnetic simulations successfully reproduced the experimental selection rules and frequencies, enabling unambiguous assignment of spin oscillation manners.
• The IC-2 phase exhibited excitation modes similar to the SkL state, and a novel B' phase with four modes active to B_{ν}⊥c was discovered.

Conclusions:

• The study provides a fundamental understanding of resonant spin dynamics in polar magnets.
• VOSe_{2}O_{5} is established as a unique material platform for hosting a rich variety of nontrivial spin excitations.
• The findings contribute to the comprehensive characterization of complex magnetic phenomena in polar materials.