Effect of Nonmagnetic Substituents Mg and Zn on the Phase Competition in the Multiferroic Antiferromagnet MnWO₄

Abstract

The effects of substituting nonmagnetic Mg 2+ and Zn 2+ ions for the Mn 2+ (S = 5/2) ions on the structural, magnetic and dielectric properties of the multiferroic frustrated antiferromagnet MnWO 4 were investigated. Polycrystalline samples of Mn 1-x Mg x WO 4 and Mn 1-x Zn x WO 4 (0 ≤ x ≤ 0.3) solid solutions were prepared by a solid-state route and characterized via X-ray and neutron diffraction, magnetization, and dielectric permittivity measurements. Mg and Zn substitutions give rise to very similar effects. The Néel temperature T N , the AF3-to-AF2 magnetic phase transition temperature T 2 , and the critical ferroelectric temperature T c = T 2 of MnWO 4 are reduced upon the nonmagnetic doping.At the lowest temperature (T = 1.5 K), the incommensurate magnetic structure for x(Mg) = 0.15 and x(Zn) = 0.15 corresponds to either a sinusoidal spin arrangement or an elliptical spin-spiral phase similar to the polar AF2 structure observed in MnWO 4 . These findings were discussed by considering the effects of the Mg and Zn substitutions on the crystal lattice and on the spin exchange network of MnWO 4 .

Crystal structure, incommensurate magnetic order, and ferroelectricity inMn1−xCuxWO4 (0 ≤xKumar1, Xiao2, Lunkenheimer3 et al. 2015Phys. Rev. B238240View full textAdd to dashboardCite

“…Evidence for the increase of K with Fe substitution was also derived from neutron scattering experiments [20]. It was observed that in Mn 1−x M x WO 4 (M=Mg, Zn and x ≤ 0.3), the substitution of the nonmagnetic Mg 2+ ions and Zn 2+ for the magnetic Mn 2+ ions result in very similar effects on the magnetic and dielectric properties of MnWO 4 [21]. These substitutions destabilized the nonpolar magnetic structure AF1 of MnWO 4 but the AF3-to-AF2 magnetoelectric phase transition was not affected.…”

Control of the multiferroic transition in Ni3V2OKumarasiri1, Lawes2 2011Phys. Rev. B271170View full textAdd to dashboardCite

“…Similar studies have been done on MnWO 4 , where magnetic Mn 2+ ions were substituted by nonmagnetic Zn and Mg. In these investigations, it was observed that the phase transition temperatures were also suppressed linearly with doping fraction [17]. Another recent study finds that the multiferroic phase of MnWO 4 is also remarkably stable against such doping by non magnetic ion, which persists up to a 50 at% Zn fraction [18].…”

Neutron diffraction, magnetic, and magnetoelectric studies of phase transitions in multiferroic Mn0.90Co0.10WOUrcelay-Olabarría1, Ressouche2, Mukhin3 et al. 2012Phys. Rev. B237390View full textAdd to dashboardCite

“…In order to enlarge the temperature range where the multiferroic phase is stable, MnWO 4 has been doped with isovalent metal and nonmetal ions. [13][14][15][16][17][18][19][20] It turned out that doping with Co 2+ is particularly interesting since it strongly stabilizes the multiferroic phase at low temperatures. According to preliminary data on powder samples, 16 the incommensurate multiferroic AF2 phase is expected to substitute the commensurate AF1 ordering at low temperature for cobalt doping above 3%.…”