论文标题
原始和GE掺杂的COCR $ _2 $ o $ _4 $中的磁场依赖性环形轮换
Magnetic field dependent cycloidal rotation in pristine and Ge doped CoCr$_2$O$_4$
论文作者
论文摘要
我们报告了一项柔软的X射线谐振磁散射研究，对Co $ $ _ {0.975} $ ge $ _ {0.025} $ CR $ cr $ _2 $ _2 $ _4 $ _4 $（ge-cco）和cocr $ _2 $ $ _4 $ _4 $（CCO）的多用量薄膜中的旋转构型研究。在低磁场上进行GE-CCO的结果，并将结果与纯CCO进行比较。 Ferrimagnetic相变温度$ T_C \约95 $ K，而多铁质过渡温度$ T_S \大约27 $ k在GE-CCO中与CCO中观察到的相当。在GE-CCO中，与CCO相比，在$ t_s $下观察到的订购波矢量$ \ textit {（qq0）} $略大，并且与CCO不同，衍射强度由两种贡献组成，这些贡献显示出不同的X射线极化依赖性。在GE-CCO中，在低温下观察到的强制场大于CCO报道的强制场。在这两种化合物中，螺旋螺旋性的意外逆转，因此在简单的磁场冷却下观察到电偏振。此外，我们发现在GE-CCO的磁衍射峰中，螺旋度随动量转移的函数发生了变化，这表明存在多个磁性螺旋。
We report a soft x-ray resonant magnetic scattering study of the spin configuration in multiferroic thin films of Co$_{0.975}$Ge$_{0.025}$Cr$_2$O$_4$ (Ge-CCO) and CoCr$_2$O$_4$ (CCO), under low- and high-magnetic fields, from 0.2 T up to 6.5 T. A characterization of Ge-CCO at a low magnetic field is performed and the results are compared to those of pure CCO. The ferrimagnetic phase transition temperature $T_C \approx 95$ K and the multiferroic transition temperature $T_S \approx 27$ K in Ge-CCO are comparable to those observed in CCO. In Ge-CCO, the ordering wave vector $\textit{(qq0)}$ observed below $T_S$ is slightly larger compared to that of CCO, and, unlike CCO, the diffraction intensity consists of two contributions that show a dissimilar x-ray polarization dependence. In Ge-CCO, the coercive field observed at low temperatures was larger than the one reported for CCO. In both compounds, an unexpected reversal of the spiral helicity and therefore the electric polarization was observed on simply magnetic field cooling. In addition, we find a change in the helicity as a function of momentum transfer in the magnetic diffraction peak of Ge-CCO, indicative of the presence of multiple magnetic spirals.
