Pan B Y, Xu H C, Liu Y, Sutarto R, He F, Shen Y, Hao Y Q, Zhao J, Harriger Leland, Feng D L
State Key Laboratory of Surface Physics, Department of Physics, and Advanced Materials Laboratory, Fudan University, Shanghai 200433, China.
School of Physics and Optoelectronic Engineering, Ludong University, Yantai, Shandong 264025, China.
Phys Rev B. 2020 Sep;102(10). doi: 10.1103/physrevb.102.104432.
CrAs is a well-known helimagnet with the double-helix structure originating from the competition between the Dzyaloshinskii-Moriya interaction (DMI) and antiferromagnetic exchange interaction . By resonant soft-x-ray scattering, we observe the magnetic peak (0 0 ) that emerges at the helical transition with ≈ 267.5 K. Intriguingly, the helimagnetic domains significantly shrink on cooling below ~255 K, opposite to the conventional thermal effect. The weakening of DMI on cooling is found to play a critical role here. It causes the helical wave vector to vary, ordered spins to rotate, and extra helimagnetic domain boundaries to form at local defects, thus leading to the anomalous shrinkage of helimagnetic domains. Our results indicate that the size of magnetic helical domains can be controlled by tuning DMI in certain helimagnets.
CrAs是一种著名的螺旋磁体，具有双螺旋结构，源于Dzyaloshinskii-Moriya相互作用（DMI）和反铁磁交换相互作用之间的竞争。通过共振软X射线散射，我们观察到在螺旋转变温度约为267.5 K时出现的磁峰（0 0）。有趣的是，在冷却至约255 K以下时，螺旋磁畴显著收缩，这与传统的热效应相反。研究发现，冷却时DMI的减弱在此起着关键作用。它导致螺旋波矢发生变化，有序自旋发生旋转，并在局部缺陷处形成额外的螺旋磁畴边界，从而导致螺旋磁畴异常收缩。我们的结果表明，在某些螺旋磁体中，可以通过调节DMI来控制磁性螺旋畴的大小。
