Spin anisotropy in Cu en H2O 2SO4 A quasi two dimensional S 1 2 spatially anisotropic triangular lattice antiferromagnet

We have studied in detail the effect of the spin anisotropy on the electron paramagnetic resonance spectra and magnetic properties of Cu en H2O 2SO4, an S 1 2 spatially anisotropic triangular lattice antiferromagnet. The angular and temperature dependence of the resonance fields as well as the magnetization and magnetic susceptibility reflect the exchange and g factor anisotropy with Jz Jx,y lt; 1 and gz gx,y gt; 1, respectively. The exchange anisotropy and Dzyaloshinskii Moriya interaction are responsible for the main broadening mechanism at higher temperatures while spin diffusion effects prevail at helium temperatures. The ratio of the uniform susceptibilities calculated along the three crystal directions suggests an easy axis anisotropy with the a axis as the magnetic easy axis. Its impact on the physical properties of the title compound is discusse