科研之友
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摘要
We discuss dynamic spin susceptibility (DSS) in two-dimensional (2D) Dirac electrons with spin-orbit interactions to characterize topological insulators. The imaginary part of the DSS appears as an absorption rate in response to a transverse ac magnetic field, just as in an electron spin resonance experiment for localized spin systems. We found that when the system is in a static magnetic field, the topological state can be identified by an anomalous resonant peak of the imaginary part of the DSS as a function of the frequency of the transverse magnetic field omega. In the absence of a static magnetic field, the imaginary part of the DSS becomes a continuous function of omega with a threshold frequency omega(c). In this case, the topological and the trivial phases can also be distinguished by the values of omega(c) and by the line shapes. Thus the DSS is an experimentally observable physical quantity to characterize a topological insulator directly from bulk properties, without observing a topological transition.
- 出版日期2016-8-26
