Laboratory of Physics of Complex Systems, University of Picardie, 33 rue Saint-Leu, 80000 Amiens, France.
Phys Rev Lett. 2011 Jun 24;106(25):257601. doi: 10.1103/PhysRevLett.106.257601. Epub 2011 Jun 20.
The incommensurate-commensurate phases reported in cupric oxide below 230 K are shown theoretically to realize an inverted sequence of symmetry-breaking mechanisms with respect to the usual sequence occurring in low-temperature multiferroic compounds. The sequence inversion results from a strong triggering-coupling mechanism between two antiferromagnetic order parameters inducing a first-order transition to the multiferroic phase. Such mechanism is favored by the large antiferromagnetic superexchange interactions, responsible of the high-T(N) temperature, and implies a preeminence of these interactions on the magnetocrystalline anisotropy. The magnetic structures of the equilibrium phases and the microscopic interactions giving rise to the polarization are determined.
在 230K 以下的氧化铜中，报道了不调和-调和相，理论上表明它们实现了相对于低温多铁化合物中常见的对称破缺机制的逆序。这种顺序的反转是由两个反铁磁有序参数之间的强触发耦合机制引起的，该机制导致了多铁相的一级相变。这种机制受到高 T（N）温度下的大反铁磁超交换相互作用的青睐，并且意味着这些相互作用对磁晶各向异性的优势。确定了平衡相的磁结构和产生极化的微观相互作用。
