用康普顿散射研究氧电子在La $_{2-2x}$ Sr $_{1+2x}$ Mn $_2$ O $_7$中的金属-绝缘体转变中的作用
Role of Oxygen Electrons in the Metal-Insulator Transition in the Magnetoresistive Oxide La$_{2-2x}$Sr$_{1+2x}$Mn$_2$O$_7$ Probed by Compton Scattering
摘要：
本文研究了双层锰氧化物中康普顿剖面的[100]-[110]各向异性。定量的协议之间的理论和实验发现，相对于在两个金属相（即低温铁磁和庞磁阻相下的磁场为7 T）的各向异性。在居里温度以上的顺磁相的动量密度中确定了金属-绝缘体转变的鲁棒签名。我们解释我们的结果提供了直接的证据，从金属类的过渡到混合离子共价键伴随着磁性转变。参与此相变的电子的数量估计由康普顿轮廓各向异性差异所包围的区域。我们的研究证明了康普顿散射技术的灵敏度，用于识别参与金属-绝缘体转变的电子的数量和类型。
英文摘要：
We have studied the [100]-[110] anisotropy of the Compton profile in the bilayer manganite. Quantitative agreement is found between theory and experiment with respect to the anisotropy in the two metallic phases (i.e. the low temperature ferromagnetic and the colossal magnetoresistant phase under a magnetic field of 7 T). Robust signatures of the metal-insulator transition are identified in the momentum density for the paramagnetic phase above the Curie temperature. We interpret our results as providing direct evidence for the transition from the metallic-like to the admixed ionic-covalent bonding accompanying the magnetic transition. The number of electrons involved in this phase transition is estimated from the area enclosed by the Compton profile anisotropy differences. Our study demonstrates the sensitivity of the Compton scattering technique for identifying the number and type of electrons involved in the metal-insulator transition.
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