Linear magnetoelectric effect in göthite, α-FeOOH.

By means of symmetry analysis, density functional theory calculations, and Monte Carlo simulations we show that goethite, α-FeOOH, is a linear magnetoelectric below its Neel temperature T N = 400 K. The experimentally observed magnetic field induced spin-flop phase transition results in either change of direction of electric polarization or its suppression. Estimated value of magnetoelectric coefficient is 0.57 μC · m−2 · T−1. The abundance of goethite in nature makes it arguably the most widespread magnetoelectric material.