Tarasenko, R.; Orendacova, A.; Cizmar, E.; Matas, S.; Orendac, M.; Potocnak, I.; Siemensmeyer, K.; Zvyagin, S.; Wosnitza, J.; Feher, A.: Spin anisotropy in Cu(en)(H2O)2SO4: A quasi-two-dimensional S = 1/2 spatially anisotropic triangular-lattice antiferromagnet. Physical Review B 87 (2013), p. 174401/1-8
10.1103/PhysrevB.87.174401

Abstract:
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 < 1 and gz/gx,y > 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 discussed.