Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands.
Nat Mater. 2012 Jun 24;11(8):694-9. doi: 10.1038/nmat3358.
The random fluctuations of spins give rise to many interesting physical phenomena, such as the 'order-from-disorder' arising in frustrated magnets and unconventional Cooper pairing in magnetic superconductors. Here we show that the exchange of spin waves between extended topological defects, such as domain walls, can result in novel magnetic states. We report the discovery of an unusual incommensurate phase in the orthoferrite TbFeO(3) using neutron diffraction under an applied magnetic field. The magnetic modulation has a very long period of 340 Å at 3 K and exhibits an anomalously large number of higher-order harmonics. These domain walls are formed by Ising-like Tb spins. They interact by exchanging magnons propagating through the Fe magnetic sublattice. The resulting force between the domain walls has a rather long range that determines the period of the incommensurate state and is analogous to the pion-mediated Yukawa interaction between protons and neutrons in nuclei.
自旋的随机涨落导致了许多有趣的物理现象，如在受挫磁体中出现的“无序有序”以及在磁性超导体中出现的非常规库珀配对。在这里，我们表明，扩展拓扑缺陷（如畴壁）之间的自旋波交换可以导致新的磁态。我们报告了在施加磁场下使用中子衍射在正交铁氧体 TbFeO(3) 中发现的异常非调幅相。在 3 K 时，磁调制具有非常长的 340 Å 周期，并表现出异常多的高次谐波。这些畴壁是由类 Ising 的 Tb 自旋形成的。它们通过在 Fe 磁子晶格中传播的交换磁子相互作用。畴壁之间的相互作用力具有相当长的范围，这决定了非调幅状态的周期，类似于原子核中质子和中子之间介子介导的 Yukawa 相互作用。
