title: Pressure effects on Emim[FeCl4], a magnetic ionic liquid with three-dimensional magnetic ordering.
abstract: We report a combined study using magnetization and Raman spectroscopy on the magnetic ionic liquid 1-ethyl-3-methylimidazolium tetrachloroferrate, Emim[FeCl4]. This material shows a long-range antiferromagnetic ordering below the Néel temperature T(N) ≈ 3.8 K. The effects of pressure on the magnetic properties have been studied using a miniature piston-cylinder CuBe pressure cell. This three-dimensional ordering is strongly influenced when hydrostatic pressure is applied. It is observed that low applied pressure is enough to modify the magnetic interactions, inducing a transition from antiferromagnetic to ferrimagnetic ordering. Raman spectroscopy measurements reveal important information about the existence of isolated [FeCl4](-) anions and the absence of dimeric [Fe2Cl7](-) units in the liquid and solid states. These features seem to suggest that the superexchange pathways responsible for the appearance of magnetic ordering are mediated through Fe-Cl-Cl-Fe. Furthermore, the liquid-solid phase transition exhibits a magnetic hysteresis near room temperature, which can be tuned by weak pressures.
authors: CITIMAC & MAGMA, Unidad Asociada-CSIC, Facultad de Ciencias, Universidad de Cantabria, 39005 Santander, Spain.
authors: Abel
authors: A
authors: García-Saiz
authors: Imanol
authors: I
authors: de Pedro
authors: Jesús A
authors: JA
authors: Blanco
authors: Jesús
authors: J
authors: González
authors: Jesús
authors: J
authors: Rodríguez Fernández