论文标题
cofe $ _2 $ o $ $ _4 $和la $ _ $ _ {0.5} $ sr $ _ {0.5} $ COO $ _3 $氧化物由差分X射线吸收光谱确定的氧化物的原子级机制
Atomic-scale mechanisms for magnetostriction in CoFe$_2$O$_4$ and La$_{0.5}$Sr$_{0.5}$CoO$_3$ oxides determined by differential x-ray absorption spectroscopy
论文作者
论文摘要
COFE $ _2 $ o $ $ _4 $和LA $ _ {0.5} $ sr $ _ {0.5} $ COO $ _3 $ polycrystalline样品已通过不同的扩展扩展X射线吸收良好结构（DiffeXafs）识别。我们证明了八面体部位的钴原子是其磁曲折的原因。 DIFFEXAFS数据的分析表明，在这两个氧化物中，CO原子的局部位点磁静脉菌株与宏观磁截图一致。 For the CoFe$_2$O$_4$ spinel, a large negative strain along the (100) direction has been determined for the CoO$_6$ octahedron causing a tetragonal contraction in contrast with the La$_{0.5}$Sr$_{0.5}$CoO$_3$ perovskite, where a positive moderate strain along the (100) direction was found resulting in a tetragonal 扩张。从两种氧化物的CO原子的不同价和自旋态来理解不同的局部磁曲折。然后，将通过相对变化的体积变化来解释宏观Magnetostriction，Cofe $ _2 $ o $ _4 $中的收缩或La $ _ {0.5} $ _ {0.5} $ sr $ _ {0.5} $ _ {0.5} $ coo $ _3 $，当Co $ _3 $，当Co Etter oft extermentife extermentife externeptional externement externally externeptional externement externeptional externeptional externecties farnity。
The atomic environments involved in the magnetostriction effect in CoFe$_2$O$_4$ and La$_{0.5}$Sr$_{0.5}$CoO$_3$ polycrystalline samples have been identified by differential extended x-ray absorption fine structure (DiffEXAFS) spectroscopy. We demonstrate that cobalt atoms at octahedral sites are responsible for their magnetostriction. The analysis of DiffEXAFS data indicates that the local-site magnetostrictive strains of Co atoms are reversed in these two oxides, in agreement with the macroscopic magnetostriction. For the CoFe$_2$O$_4$ spinel, a large negative strain along the (100) direction has been determined for the CoO$_6$ octahedron causing a tetragonal contraction in contrast with the La$_{0.5}$Sr$_{0.5}$CoO$_3$ perovskite, where a positive moderate strain along the (100) direction was found resulting in a tetragonal expansion. The different local-site magnetostriction is understood in terms of the different valence and spin state of the Co atoms for the two oxides. The macroscopicmagnetostriction would be explained then by the relative change in volume, either contraction in CoFe$_2$O$_4$ or expansion in La$_{0.5}$Sr$_{0.5}$CoO$_3$, when the tetragonal axis of the Co site is reoriented under an externally applied magnetic field.
