发表机构
Ames National Laboratory, U.S. Department of Energy, Iowa State University（艾姆斯国家实验室，美国能源部，爱荷华州立大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过脉冲激光沉积在Si衬底上生长HoCo$_2$薄膜，表征其结构、电子和磁性质，发现薄膜保持亚铁磁转变但变为二级转变，且矫顽力显著增大。
AI 中文摘要
我们报道了通过脉冲激光沉积在Si衬底上生长的HoCo$_2$薄膜的生长及其物理性质。X射线反射率数据中清晰的Kiessig条纹给出了$35 \pm 1$~nm的薄膜厚度，并展示了光滑的薄膜表面和界面轮廓。原子力显微镜证实了薄膜的高形态质量，揭示了约170~pm的亚纳米表面粗糙度。两个独立制备的薄膜在$T_{\mathrm{C}}=77\pm3$~K处表现出可重复的亚铁磁转变，证明了块体HoCo$_2$的特征磁有序得以保留。然而，无可分辨的热滞回表明薄膜中主要为连续的、类似二级的转变，这与块体HoCo$_2$的一级转变形成对比。在5~K时，薄膜表现出明显的磁滞回线，矫顽场约为600~Oe，远大于块体HoCo$_2$的可忽略的矫顽力。X射线光电子能谱显示，块体和薄膜的Ho $4d$和Co $2p$芯能级线形相似，价带谱也大致相同，表明基本的局域电子环境和占据电子结构得以保留。
英文摘要
We report the growth and physical properties of HoCo$_2$ thin films on Si substrate by pulsed laser deposition. Well-defined Kiessig fringes in the x-ray reflectivity data yield a film thickness of $35 \pm 1$~nm and demonstrate smooth film surface and interface profiles. Atomic force microscopy confirms the high morphological quality of the films, revealing subnanometer surface roughness of $\sim$170~pm. Two independently prepared films exhibit a reproducible ferrimagnetic transition at $T_{\mathrm{C}}=77\pm3$~K, demonstrating retention of the characteristic magnetic ordering of bulk HoCo$_2$. However, the absence of resolvable thermal hysteresis indicates a predominantly continuous, second-order like transition in the films, in contrast to the first-order transition of bulk HoCo$_2$. At 5~K, the films exhibit clear magnetic hysteresis with a coercive field of $\sim$600~Oe, substantially larger than the negligible coercivity of bulk HoCo$_2$. X-ray photoelectron spectroscopy reveals comparable Ho $4d$ and Co $2p$ core-level line shapes and broadly similar valence-band spectra for the bulk and film, indicating preservation of the essential local electronic environment and occupied electronic structure.
