Calculation of magnetic exchange couplings in the S=3/2 honeycomb system (Bi3Mn4O12)NO3 from first principles

Absence of magnetic ordering in Bi3Mn4O12(NO3) (BMNO) which has a magnetic subsystem that consists of honeycomb bilayers of Mn4+ ions with spin S = 3/2 has raised the expectation that its ground state is strongly frustrated due to longer range antiferromagnetic interactions. We calculate the magnetic exchange coupling constants of the BMNO complex within a density functional approach and find that the dominating interactions between Mn spins are the antiferromagnetic nearest-neighbor J(1) and the effective interlayer interaction J(c). The largest interaction is J(c), which substantially exceeds J(1). Longer range interactions are antiferromagnetic but not strongly frustrating.