Magnetocapacitance Effect and Magnetoelectric Coupling in Type-II Multiferroic HoFeWO₆

We have studied the magnetocapacitance (MC) effect and magnetoelectric (ME) coupling in HoFeWO₆, a type-II multiferroic with an onset of electric polarization and an antiferromagnetic (AFM) ordering at the Neel temperature (T_N) of 17.8 K. With a polar structure at room temperature, our X-ray diffraction measurements did not show any structural phase transition across T_N, consistent with our density functional theory calculations. Our X-ray absorption spectroscopy and X-ray magnetic circular dichroism revealed the valence state of 3+ for Fe and Ho cations and AFM ordering of Fe³⁺ spins in a non-collinear fashion with spins arranged 90 degrees with respect to each other. The compound exhibits MC effect with double-hysteresis loop behavior that is in direct correspondence with the magnetization. The observed MC effect and the change in polarization by the magnetic field, as well as their direct correspondence with magnetization, further support the strong ME coupling in this compound.