Helmholtz-Zentrum Berlin für Materialien und Energie, Wilhelm-Conrad-Röntgen-Campus BESSY II, Albert-Einstein-Str. 15, D-12489 Berlin, Germany.
Phys Rev Lett. 2010 Oct 15;105(16):167207. doi: 10.1103/PhysRevLett.105.167207.
Using soft x-ray diffraction at the Dy-M₅ resonance, pronounced circular dichroism in the ferroelectric phase of DyMnO₃ is observed in connection with sizable b and c components of the Dy-4f magnetic moments. This provides strong evidence for cycloidal order of the 4f moments, corroborating that inversion-symmetry breaking in this material is not accomplished by the Mn spins alone. The 4f circular dichroism allows us to image multiferroic domains that are imprinted on the surface of DyMnO₃ using the local charging by the x-ray beam via the photoelectric effect.
利用软 X 射线在 Dy-M₅共振处的衍射，我们观察到 DyMnO₃铁电相中的显著圆二色性与 Dy-4f 磁矩的 b 和 c 分量有关。这为 4f 磁矩的回旋有序提供了强有力的证据，证实了这种材料中反演对称性的破坏不是由 Mn 自旋单独完成的。4f 圆二色性使我们能够通过光电效应，利用 X 射线束对表面的局部充电，对 DyMnO₃ 表面上的多铁畴进行成像。
