Magnetic fluctuations above the Néel temperature in κ-(BEDT-TTF)2Cu[N(CN)2]Cl, a quasi-2D Heisenberg antiferromagnet with Dzyaloshinskii-Moriya interaction

We report on magnetic fluctuations studied by electron spin resonance (ESR) spectroscopy in the layered organic crystal ?-(BEDT-TTF)2Cu[N(CN)2]Cl. A line broadening above the antiferromagnetic ordering temperature, TN?=?23?K is attributed to two-dimensional magnetic fluctuations of a staggered magnetization induced by the interplay of the magnetic field and the DzyaloshinskiiMoriya (DM) interaction.