2D ferromagnetism in porphyrin-based semiconductors

We study an environmentally stable 2D ferromagnetic semiconductor with applications in biomedicine, solar cells, spintronics, and energy and hydrogen storage. We describe the electronic, transport, optical, and magnetic properties of a π-conjugated micropore polymer with three iron atoms placed in the middle of an isolated pore. We study how these properties change when bonded with CO, CO₂, and O₂. This material exhibits strong Fe-localized d_z² bands with a direct bandgap of 0.28 eV. The material is a ferromagnet of an Ising type with long-range exchange interactions with a very high magnetic moment per unit cell, m = 6 μ_B. The estimated exchange integral is calculated to be about J_nn = 25 meV. The binding of CO, CO₂, and O₂ modifies the d_z² bands of the Fe ions with varying indirect bandgaps with values between 0.269 - 0.626 eV, 0.039 - 0.434 eV, and 0.291 - 0.347 eV for CO, CO₂, and O₂, respectively. Both the absorption coefficient and conductivity have large modifications to the xy-components. The material remains ferromagnetic with the magnetic moment per unit cell decreasing to 4, 2, and 0 μ_B for gases attached to one, two, and three Fe ions per unit cell, respectively.