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Scientists Find Broken Mirror Symmetry Tuned Topological Transport in PbTe/SnTe Heterostructures

Jan 09, 2019     Email"> PrintText Size

Topological crystalline insulator (TCI) is a new type of topological materials whose metallic topological surface states (TSSs) are protected by the crystalline mirror symmetry, not by the time reversal symmetry as in topological insulators.

Recently, Prof. ZHANG Zhidong and Prof. MA Song from Institute of Metal Research of Chinese Academy of Sciences, collaborating with Prof. Xuan P. A. Gao from Case Western Reserve University, fabricated a new PbTe/SnTe heterostructure by constructing the band insulator PbTe and TCI SnTe on SrTiO3(111) substrate.

If the linear magneto-resistance (LMR), a novel magneto-resistance behavior, could be realized in TCI films and its topological surface states could be modulated by crystalline lattice symmetry, it will be of great significance not for the application of topological crystal insulators in spintronics devices, as well as the theoretical study of transport mechanism of topological crystalline insulators.

In the study, the giant linear magneto-resistance with value 2150% was observed at 2K and 14T, andthe strong metallic conduction likely induced by Dirac fermions with high mobility was discovered.

By diffusion of Pb atoms into SnTe layer on the interface of PbTe/SnTe heterostructure, the cubic-rhombohedral structural phase transition in SnTe is induced and its crystalline symmetry is subsequently broken, which transforms LMR to the typical weak antilocalization.

Furthermore, the LMR in PbTe/SnTe heterostructure was measured by Van de Pauw geometry and confirmed by Corbino geometry. The multiple-carrier transport in PbTe/SnTe heterostructure was detected in which the surface state Dirac electrons dominated the strong metallic conduction at low temperature and the bulk holes dominated the weak metallic conduction at room temperature.

The study showed that the present LMR in PbTe/SnTe heterosturcture cannot be well described by the classical Drude model, which highlights an unusual magneto-transport character of topological materials that challenges the standard Drude picture of electron transport.

These findings have been published on Physical Review B (Rapid Communications) and Nano LettersNano Letters.

(Editor: LIU Jia)


HUANG Chengyu

Institute of Metal Research

E-mail: cyhuang@imr.ac.cn

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