The ground state structural, electronic, and magnetic properties of multiferroic ${\mathrm{TbMn}}_2{\mathrm{O}}_5$ are investigated via first-principles calculations. We show that the ferroelectricity in ${\mathrm{TbMn}}_2{\mathrm{O}}_5$ is driven by the noncentrosymmetric magnetic ordering, without invoking the spin-orbit coupling and noncollinear spins. The intrinsic electric polarization in this compound is calculated to be $1187\mathrm{nC}{\mathrm{cm}}^{-2}$, an order of magnitude larger than previously thought.

• Received 18 April 2007

DOI:https://doi.org/10.1103/PhysRevLett.99.177202