Long-range magnetic ordering in magnetic ionic liquid: Emim[FeCl4]

Up to now most of the magnetic ionic liquids containing tetrachloroferrate ion FeCl4 have evidenced a paramagnetic temperature dependence of the magnetic susceptibility, with only small deviations from the Curie law at low temperatures. However, we report on the physical properties of 1-ethyl-3-methylimidazolium tetrachloroferrate Emim[FeCl4], that clearly shows a long-range antiferromagnetic ordering below the Neel temperature T-N approximate to 3.8 K. In addition, the field dependence of the magnetization measured at 2 K is characterized by a linear behaviour up to around 40 kOe, while above this field the magnetization becomes saturated with a value of 4.3 mu(B)/Fe, which is near the expected fully saturated value of 5 mu(B)/Fe for an Fe3+ ion.status: publishe