Symmetric and antisymmetric exchange anisotropies in quasi-one-dimensional CuSe${}_2$O${}_5$ as revealed by ESR

We present an electron spin resonance (ESR) study of single-crystalline spin chain-system CuSe${}_2$O${}_5$ in the frequency range between 9 GHz and 450 GHz. In a wide temperature range above the N'{e}el temperature $T_N=17$ K we observe strong and anisotropic frequency dependence of a resonance linewidth. Although sizeable interchain interaction $J_{IC}\approx 0.1J$ ($J$ is the intrachain interaction) is present in this system, the ESR results agree well with the Oshikawa-Affleck theory for one-dimensional $S=1\mathrm{/}2$ Heisenberg antiferromagnet. This theory is used to extract the anisotropies present in CuSe${}_2$O${}_5$. We find that the symmetric anisotropic exchange $J_c=(0.04\pm 0.01)J$ and the antisymmetric Dzyaloshinskii-Moriya (DM) interaction $D=(0.05\pm 0.01)J$ are very similar in size in this system. Staggered-field susceptibility induced by the presence of the DM interaction is witnessed in the macroscopic susceptibility anisotropy.