Bilayer Mott System with Cation···Anion Supramolecular Interactions Based on a Nickel Dithiolene Anion Radical: Coexistence of Ferro- and Antiferromagnetic Anion Layers and Large Negative Magnetoresistance

Abstract

A novel bilayer Mott system, (Et-4BrT)[Ni(dmit)2]2 (Et-4BrT = ethyl-4-bromothiazolium; dmit = 1,3-dithiole-2-thione-4,5-dithiolate), contains two nonequivalent Ni(dmit)2 anion layers, where both layers form Mott insulating states. Supramolecular Br(cation)···S(anion) and S(cation)···S(anion) interactions play a crucial role in constructing the bilayer structure. The ferro- and antiferromagnetic short-range-ordering layers coexist in the crystal, which achieves large negative magnetoresistance (Δρ/ρ0 ≈ -75% at 70 kOe) at 5 K under 1 GPa.