Topological insulators （TIs） are a new state of quantum matter with a band gap in bulk and conducting surface states. In this work, the Raman spectra of topological insulator Bi2Te3 films prepared by molecular beam ...Topological insulators （TIs） are a new state of quantum matter with a band gap in bulk and conducting surface states. In this work, the Raman spectra of topological insulator Bi2Te3 films prepared by molecular beam epitaxy （MBE） have been measured by an in situ ultrahigh vacuum （UHV）-MBE-Raman spectroscopy system. When the thickness of Bi2Te3 films decreases from 40 quintuple-layers （QL） to 1 QL, the spectral characteristics of some Raman modes appearing in bulk Bi2Te3 vary and a new vibrational mode appears, which has not been reported in previous studies and might be related to quantum size effects and symmetry breaking. In addition, an obvious change was observed at 3 QL when a Dirac cone formed. These results offer some new information about the novel quantum states of TIs.展开更多
In this article we review recent transport property studies on topological insulator thin films grown by molecular beam epitaxy.In pure Bi2Se3 ultrathin films we find an insulating ground state in the presence of weak...In this article we review recent transport property studies on topological insulator thin films grown by molecular beam epitaxy.In pure Bi2Se3 ultrathin films we find an insulating ground state in the presence of weak antilocalization,which indicates the relevance of electron interaction effect.In magnetically doped Bi2Se3 film we observe a systematic crossover between weak localization and weak antilocalization with varied magnetic doping,temperature,and magnetic field.These results demonstrate the intricate interplay between topological delocalization,electron interaction,and broken time reversal symmetry in topological insulator thin films.展开更多
文摘Topological insulators （TIs） are a new state of quantum matter with a band gap in bulk and conducting surface states. In this work, the Raman spectra of topological insulator Bi2Te3 films prepared by molecular beam epitaxy （MBE） have been measured by an in situ ultrahigh vacuum （UHV）-MBE-Raman spectroscopy system. When the thickness of Bi2Te3 films decreases from 40 quintuple-layers （QL） to 1 QL, the spectral characteristics of some Raman modes appearing in bulk Bi2Te3 vary and a new vibrational mode appears, which has not been reported in previous studies and might be related to quantum size effects and symmetry breaking. In addition, an obvious change was observed at 3 QL when a Dirac cone formed. These results offer some new information about the novel quantum states of TIs.
基金supported by the National Natural Science Foundation of China(Grant Nos.10834003,10911130233)the Ministry of Science and Technology of China(Grant No.2009CB929400)the Chinese Academy of Sciences
文摘In this article we review recent transport property studies on topological insulator thin films grown by molecular beam epitaxy.In pure Bi2Se3 ultrathin films we find an insulating ground state in the presence of weak antilocalization,which indicates the relevance of electron interaction effect.In magnetically doped Bi2Se3 film we observe a systematic crossover between weak localization and weak antilocalization with varied magnetic doping,temperature,and magnetic field.These results demonstrate the intricate interplay between topological delocalization,electron interaction,and broken time reversal symmetry in topological insulator thin films.
