Tolédano P, Ayala A P, Furtado Filho A F G, do Nascimento J P C, Silva M A S, Sombra A S B
Laboratoire de Physique des Systèmes Complexes, Université de Picardie, 80000 Amiens, France.
J Phys Condens Matter. 2017 Jan 25;29(3):035701. doi: 10.1088/1361-648X/29/3/035701. Epub 2016 Nov 21.
The nature and symmetry of transition mechanisms in the spin-spiral copper halides CuCl and CuBr are analyzed theoretically. The magnetoelectric effects observed in the two multiferroic compounds are described and their phase diagram at zero and applied magnetic fields are worked out. The emergence of the electric polarization at zero field below the paramagnetic phase is shown to result from the coupling of two distinct spin-density waves and to be only partly related to the Dzialoshinskii-Moriya interactions. Applying a magnetic field along the two-fold monoclinic axis of CuCl yields a decoupling of the spin-density waves modifying the symmetry of the phase and the spin-spiral orientation. The remarkable periodic dependences of the magnetic susceptibility and polarization, on rotating the field in the monoclinic plane, are described theoretically.
从理论上分析了自旋螺旋卤化铜CuCl和CuBr中跃迁机制的性质和对称性。描述了在这两种多铁性化合物中观察到的磁电效应，并绘制了它们在零磁场和外加磁场下的相图。结果表明，顺磁相以下零场处出现的极化是由两种不同的自旋密度波耦合引起的，且仅部分与Dzialoshinskii-Moriya相互作用有关。沿CuCl的二重单斜轴施加磁场会导致自旋密度波解耦，从而改变相的对称性和自旋螺旋取向。理论上描述了在单斜平面内旋转磁场时，磁化率和极化的显著周期性依赖关系。
