CoFe2O4/PMN-PT纳米复合材料中自旋-声子耦合与磁电效应的相关性：拉曼光谱和XMCD研究
Correlation between spin-phonon coupling and magneto-electric effects in CoFe2O4/PMN-PT nanocomposite: Raman Spectroscopy and XMCD study
摘要：
研究了CoFe_2O_4/PMN-PT复合体系中晶格与自旋通过应变相互作用的耦合。X射线衍射和拉曼光谱研究表明，PMN-PT在居里温度（450 K）前后，CoFe 2 O 4晶格发生了显著的变化。随后，CoFe 2 O 4/PMN-PT复合材料揭示了跨PMN-PT的Tc（450 K）的磁矩的突然下降。而CoFe_2O_4在此温度范围内表现出典型的铁磁行为。这些发现建立了复合材料中CoFe_2O_4和PMN-PT之间由于界面应变传递而产生的自旋-晶格耦合。通过测量极化和未极化的电场对CoFe_2 O_4/PMN-PT复合材料的磁化强度和磁电系数的影响，证明了应变的引入导致了磁电耦合。X射线磁性圆二色性（XMCD）分析表明，极化后的CoFe 2 O 4/PMN-PT复合材料中，阳离子（Fe 3 +/Co 2+）在四面体和八面体位置发生了重新分布，证实了复合材料中磁有序和电有序之间的耦合。磁电耦合系数α随直流磁场的变化曲线表明，极化后样品的磁电耦合系数α值增大，表现出滞后行为，这是由于极化后样品中复合材料的磁畴结构发生了应变诱导的变化。这些结果表明，CoFe_2O_4/PMN-PT复合材料中自旋晶格耦合的存在可能是通过应变相互作用产生强磁电效应的机制。
英文摘要：
We have investigated the coupling of lattice with spin via strain interactions in the CoFe2O4/PMN-PT composite system. X-ray diffraction and Raman spectroscopic studies illustrate a remarkable modification in CoFe2O4lattice across Curie temperature (450 K) of PMN-PT. Subsequently, CoFe2O4/PMN-PT composite reveals a sudden drop in magnetic moment across Tc of PMN-PT (450 K). However,theindependent CoFe2O4phasedisplaystypical ferromagnetic behaviour across this temperature. These findings establish spin-lattice coupling owing to th interfacial strain transfer between CoFe2O4 and PMN-PT in composite. The strain intractions leads to magneto-electric coupling, evidenced by measuring magentization and magneto-electric coefficient for the electric field poled and unploed CoFe2O4/PMN-PT composite samples. X-ray magnetic circular dichroism (XMCD) analysis establishes that the cation (Fe3+/Co2+) redistribution occurs on tetrahedral and octahedral site in the electrically poled CoFe2O4/PMN-PT composite, confirming the coupling between magnetic and electric ordering in the composite. The magneto-electric coupling coefficient alpha vs dc magnetic field curves revealed hysteretic behavior and enhanced α values after electric poling, which originates from the strain induced modifications in the magnetic domains configuration of composite in the poled samples. These findings suggest that the existence of spin lattice coupling may leads to the mechanism of strong magneto-electric effects via strain interactions in CoFe2O4/PMN-PT composite.
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