Modification of spin-ice physics in Ho2Ti2O7 thin films
Modification of spin-ice physics in Ho2Ti2O7 thin films
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Ho2Ti2O7 薄膜中自旋冰物理的修改
DOI：
10.1103/physrevmaterials.3.084412
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发表时间：
2019
影响因子：
3.4
通讯作者：
Qiu, Y.
中科院分区：
文献类型：
--
作者：
Barry, Kevin;Zhang, Biwen;Anand, Naween;Xin, Yan;Vailionis, Arturas;Neu, Jennifer;Heikes, Colin;Cochran, Charis;Zhou, Haidong;Qiu, Y.
我们提出了一项关于衬底取向、应变、化学计量比和缺陷对生长在氧化钇稳定的氧化锆衬底上的薄膜的自旋-冰物理影响的广泛研究。我们发现不同取向的生长在薄膜中产生不同的应变态。所有薄膜的松弛部分都表现出相似的轴晶格参数，其值始终大于体积值10.1？透射电子显微镜显示薄膜中存在反位无序和生长缺陷，但没有观察到填充的证据。无序度的大小取决于生长方向，其中(110)面显示的最少。在1.8K下的磁化测量显示了与自旋冰有关的所有方向的预期磁各向异性和饱和磁化值；当比较面内和面外方向时，形状各向异性是明显的。值得注意的是，只有(110)取向的薄膜在磁化强度上显示出标志性的自旋-冰平台状态，尽管与在单晶中观察到的平台相比没有那么清晰。更无序的(111)取向薄膜上的中子散射图显示了以前在块状材料中观察到的相，但提供平台状态的相仍然难以捉摸。我们的结论是，薄膜中的自旋-冰物理受到缺陷和应变的修正，导致关联驱动系统进入自旋-冰态的温度降低。
We present an extensive study on the effect of substrate orientation, strain, stoichiometry, and defects on spin-ice physics inthin films grown onto yttria-stabilized-zirconia substrates. We find that growth in different orientations produces different strain states in the films. All films exhibit similar-axis lattice parameters for their relaxed portions, which are consistently larger than the bulk value of 10.1 Å. Transmission electron microscopy reveals antisite disorder and growth defects to be present in the films, but evidence of stuffing is not observed. The amount of disorder depends on the growth orientation, with the (110) film showing the least. Magnetization measurements at 1.8 K show the expected magnetic anisotropy and saturation magnetization values associated with a spin ice for all orientations; shape anisotropy is apparent when comparing in- and out-of-plane directions. Significantly, only the (110)-oriented films display the hallmark spin-ice plateau state in magnetization, albeit less well defined compared to the plateau observed in a single crystal. Neutron-scattering maps on the more disordered (111)-oriented films show thephase previously observed in bulk materials, but thephase giving the plateau state remains elusive. We conclude that the spin-ice physics in thin films is modified by defects and strain, leading to a reduction in the temperature at which correlations drive the system into the spin-ice state.