Competing anisotropies in the chiral cubic magnet Co$_8$Zn$_8$Mn$_4$ unveiled by resonant x-ray magnetic scattering
Victor Ukleev, Oleg I. Utesov, Chen Luo, Florin Radu, Sebastian Wintz, Markus Weigand, Simone Finizio, Moritz Winter, Alexander Tahn, Bernd Rellinghaus, Kosuke … 展开作者
Victor Ukleev, Oleg I. Utesov, Chen Luo, Florin Radu, Sebastian Wintz, Markus Weigand, Simone Finizio, Moritz Winter, Alexander Tahn, Bernd Rellinghaus, Kosuke Karube, Yoshinori Tokura, Yasujiro Taguchi, Jonathan S. White
The cubic $β$-Mn-type alloy Co$_8$Zn$_8$Mn$_4$ is a chiral helimagnet that exhibits a peculiar temperature-dependent behavior in the spiral pitch, which decreases from 130 nm at room temperature to 70 nm below 20 K. Notably, this shortening is also accompanied by a structural transition of the metastable skyrmion texture, transforming from a hexagonal lattice to a square lattice of elongated skyrmions. The underlying mechanism of these transformations remain unknown, with interactions potentially involved including temperature-dependent Dzyaloshinskii-Moriya interaction, magnetocrystalline anisotropy, and exchange anisotropy. Here, x-ray resonant magnetic small-angle scattering in vectorial magnetic fields was employed to investigate the temperature dependence of the anisotropic properties of the helical phase in Co$_8$Zn$_8$Mn$_4$. Our results reveal quantitatively that the magnitude of the anisotropic exchange interaction increases by a factor of 4 on cooling from room temperature to 20 K, leading to a 5% variation in the helical pitch within the (001) plane at 20 K. While anisotropic exchange interaction contributes to the shortening of the spiral pitch, its magnitude is insufficient to explain the variation in the spiral periodicity from room to low temperatures. Finally, we demonstrate that magnetocrystalline and exchange anisotropies compete, favoring different orientations of the helical vector in the ground state.
Anisotropies and magnetic phase transitions in insulating antiferromagnets determined by a Spin-Hall magnetoresistance probe
我们证明，我们可以确定的反铁磁各向异性和体Dzyaloshinskiii-Moriya领域的绝缘氧化铁赤铁矿，α-Fe 2 O 3，使用表面敏感的自旋霍尔磁阻（SMR）技术。我们开发了一个分析模型，结合SMR测量，允许在很宽的温度和磁场值范围内的这种原型反铁磁体的材料参数的识别。使用具有不同取向的器件，我们证明了SMR响应强烈依赖于相对于磁晶各向异性轴的充电电流的方向。我们表明，我们可以提取的各向异性在很宽的温度范围内，包括整个桑色素相变。我们观察到，电响应是由反铁磁Néel序参量的取向，而不是由新兴的弱磁矩。我们的研究结果强调，表面灵敏度的SMR允许访问的反铁磁晶体的磁各向异性，特别是薄膜，在其他方法来确定各向异性，如体积敏感的磁化率测量不提供足够的灵敏度。
Substrate induced magnetic anisotropies and magneto-optical response in YIG nanosized epitaxial films on NdGG(111)
用激光分子束外延方法在Nd 3Ga 5 O 12衬底上生长了Y3 Fe 5 O 12纳米外延薄膜。磁光极性克尔效应、铁磁共振和自旋波传播测量表明，与YIG/GGG系统相比，与应力相关的各向异性场具有相反的符号。这导致了有效磁化强度的显著降低，这为获得具有垂直磁化强度的YIG薄膜以利用前向体自旋波开辟了前景。纵向磁光克尔效应磁强计揭示了一个大的贡献二次磁化条款到介电常数张量在光学频率。这种效果强烈增加，随着温度的降低，并解释了交换耦合到Fe 3+离子的界面Nd 3+离子的磁化。
Room temperature control of axial and basal antiferromagnetic anisotropies using strain
University of Oxford（牛津大学）；University of Electronic Science and Technology of China（电子科技大学）；National University of Singapore（新加坡国立大学）；Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy（马克斯·玻恩非线性光学和短脉冲光谱研究所）；Paul Scherrer Institut（保罗谢尔研究所）
