Motivated by the discovery of multiferroicity in the geometrically frustrated triangular antiferromagnet CuCrO2 below its Néel temperature TN , we investigate its magnetic and ferroelectric properties using ab initio calculations and Monte Carlo simulations. Exchange interactions up to the third nearest neighbors in the ab plane, inter-layer interaction and single ion anisotropy constants in CuCrO2 are estimated by series of density functional theory calculations. In particular, our results evidence a hard axis along the [110] direction due to the lattice distortion that takes place along this direction below TN . Our Monte Carlo simulations indicate that the system possesses a Néel temperature TN ≈ 27 K very close to the ones reported experimentally (TN = 24 − 26 K). Also we show that the ground state is a proper-screw magnetic configuration with an incommensurate propagation vector pointing along the [110] direction. Moreover, our work reports the emergence of spin helicity below TN which leads to ferroelectricity in the extended inverse Dzyaloshinskii-Moriya model. We confirm the electric control of spin helicity by simulating P -E hysteresis loops at various temperatures.

The effects of nonmagnetic impurity doping on magnetic and ferroelectric properties of multiferroic delafossite CuCrO 2 are investigated by means of density functional theory calculations and Monte Carlo simulations. Density functional theory calculations show that replacing up to 30% of Cr 3+ ions by Ga 3+ ones does not significantly affect the remaining Cr-Cr superexchange interactions. Monte Carlo simulations show that CuCr 1−x Ga x O 2 preserves its magnetoelectric properties up to x 0.15 with a spiral ordering, while it becomes disordered at higher fractions. Antiferromagnetic transition shifts towards lower temperatures with increasing x and eventually disappears at x 0.2. Our simulations show that Ga 3+ doping increases the Curie-Weiss temperature of CuCr 1−x Ga x O 2 , which agrees well with experimental observations. Moreover, our results show that the incommensurate ground-state configuration is destabilized by Ga 3+ doping under zero applied field associated with an increase of frustration. Finally, coupling between noncollinear magnetic ordering and electric field is reported for x 0.15 through simulating P-E hysteresis loops, which leads to ferroelectricity in the extended inverse Dzyaloshinskii-Moriya model.