Spin Dynamics of Two-Dimensional Triangular-Lattice Antiferromagnet 3R-AgFeO2

Abstract

Spin dynamics of quasi two-dimensional triangular-lattice antiferromagnet delafossite 3R-AgFeO₂ have been investigated by electron spin resonance. The divergence of the temperature-dependent linewidth has been analyzed in the frame of two possible scenarios: (1) critical broadening due to slowing down of spins on approaching the Néel temperature T_N from above and (2) in terms of a Berezinski–Kosterlitz–Thouless formalism on triangular lattice due to magnetic Z₂-vortex–antivortex pairing. It has been found that the latter model gives better description of the experimental data indicating traces of Z₂-vortices formation.