Electronic and magnetic properties of π-d interaction system (EDTDM)₂FeBr₄

The crystal structure and electronic and magnetic properties of magnetic molecular conductor (EDTDM)₂FeBr₄ are investigated. The material undergoes a SDW transition at T_MI ∼ 11 K and an antiferromagnetic transition of Fe³⁺ d-spins at T_N = 3 K. In addition to the appearance of an anomaly in the resistivity around T _N, a large magnetoresistance is observed below T_N, which diverges at the critical pressure (P_c ∼ 9.2 kbar) of the MI transition. The perturbation potential from the antiferromagnetic Fe ³⁺ spin arrangement stabilizes the SDW state, leading to the anomaly in the resistivity. The application of magnetic field reduces the potential of the Fe³⁺ spins, which leads to the large negative magnetoresistance. This indicates that the π-d interaction plays an important role in the interplay between the magnetism and the electron transport.