State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China.
Department of Physics, Southeast University, Nanjing 211189, China.
Nat Commun. 2015 Feb 4;6:6179. doi: 10.1038/ncomms7179.
Recently, broken symmetry effect induced edge states in two-dimensional electronic systems have attracted great attention. However, whether edge states may exist in strongly correlated oxides is not yet known. In this work, using perovskite manganites as prototype systems, we demonstrate that edge states do exist in strongly correlated oxides. Distinct appearance of ferromagnetic metallic phase is observed along the edge of manganite strips by magnetic force microscopy. The edge states have strong influence on the transport properties of the strips, leading to higher metal-insulator transition temperatures and lower resistivity in narrower strips. Model calculations show that the edge states are associated with the broken symmetry effect of the antiferromagnetic charge-ordered states in manganites. Besides providing a new understanding of the broken symmetry effect in complex oxides, our discoveries indicate that novel edge state physics may exist in strongly correlated oxides beyond the current two-dimensional electronic systems.
最近，二维电子系统中的破对称效应诱导的边缘态引起了极大的关注。然而，强关联氧化物中是否可能存在边缘态尚不清楚。在这项工作中，我们以钙钛矿锰氧化物为原型系统，证明了强关联氧化物中确实存在边缘态。通过磁力显微镜观察到锰氧化物条带边缘出现了明显的铁磁金属相。边缘态对条带的输运性质有很强的影响，导致更窄条带的金属-绝缘转变温度更高，电阻率更低。模型计算表明，边缘态与锰氧化物中反铁磁电荷有序态的破对称效应有关。除了为复杂氧化物中的破对称效应提供新的理解之外，我们的发现表明，在当前二维电子系统之外的强关联氧化物中可能存在新的边缘态物理。
