Bipolar Magnetic Materials Based on 2D Ni[TCNE] Metal-Organic Coordination Networks

Bipolar magnetic materials can produce alternative spin currents with 100% spin-polarization by flexible electrical control, showing great potentials in spintronics. Using first-principles calculations, it is demonstrated that the 2D metal-organic coordination networks, consisting of tetracyanoethylene (TCNE) molecules and Ni atoms, labeled Ni[TCNE], are bipolar magnetic materials showing rich properties: one isomer named a-Ni[TCNE] is a bipolar magnetic semiconductor (BMS), and another isomer, p-Ni[TCNE], behaves like a bipolar magnetic metal (BMM). The proper charge transfer leads to the localized spins at the Ni atoms and delocalized spin magnetic moments on the whole structure and the coupling between the localized spins and the itinerant spins is ferromagnetic. These traits of BMS and BMM in Ni[TCNE] networks add additional features to the family of 2D bipolar magnetic materials. This study paves the way for the design of organic based 2D bipolar magnetic spintronics materials.