High field ESR measurements of quantum triple chain system Cu3(OH)4SO4

Abstract

Magnetic properties of Cu3(OH)4SO4, which is a model substance of an S = 1/2 triple chain system, have been investigated by the magnetization and the high field ESR measurements. The magnetization measurements of powder sample have been performed up to 7 T at 2 K. The derivative magnetization curve shows a jump at 1.2 T due to a magnetic phase transition. The high field ESR measurements have been performed using the pulsed magnetic field up to 16 T in the temperature range from 1.8 K to 300 K. The resonance shifts due to low dimensionality are observed below 40 K far from TN = 5.3 K. The frequency-field diagram at 1.8 K below 5 T shows AFMR modes, which can be described by conventional AFMR theory of two sublattice with an uniaxial anisotropy, and the spin flop transition field is estimated to be 1.2 T. The ESR modes above 5 T deviate from the conventional AFMR modes.