Development of high-frequency high-field ESR system and its application to spin frustration system

Abstract

Recent advances in the high-frequency high-field ESR studies of spin frustration systems are presented. The results of S=1/2 diamond chain system Cu₃OH₂(CO₃)₂ (azurite) and S=1/2 honeycomb lattice antiferromagnet lnCu_2/3V_1/3O₃ are discussed. Observation of the direct transition of azurite at 1.9K give directly the energy-field diagram of spin system. Multi-frequency ESR measurements of lnCu2/3V1/3O3 revealed that S=1/2 honeycomb lattice antiferromagnet shows anomalous spin dynamics at around Néel temperature. It suggests the possible strongly fluctuated state of spin in Néel order.