2008/08/31 by Ryuichi Shindou, Shuichi Murakami · 91 citations
Mathematics · Physics and Astronomy · #Charge (physics) #Condensed matter physics #Critical point (mathematics) #Geometry #Massless particle #Mathematical physics #Mathematics #Parity (physics) #Phase transition #Physics #Quantum and electron transport phenomena #Quantum critical point #Quantum many-body systems #Quantum mechanics #Quantum phase transition #Topological Materials and Phenomena #Zero-point energy #cond-mat.dis-nn #cond-mat.mes-hall
paper · pdf · doi:10.1103/physrevb.79.045321
published in Physical Review B 79(4) (American Physical Society) · 30 pages submitted to PRB. The standard WL calculation based on the Kubo formula is newly included, while the previous mode-mode coupling calculations are transferred to the appendices. The physical meaning of the "two-modes" is also made explicit
arxiv created 2009/01/02 · openalex publication_date 2009/01/30 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
In this paper, we address ourselves to the nonmagnetic disorder effects onto the quantum critical point, which intervenes the three-dimensional Z2 quantum spin Hall insulator (topological insulator) and an ordinary insulator. The minimal model describing this type of the quantum critical point is the single copy of the 3+1 Dirac fermion, whose topological mass m induces the phase transition between the topological insulator and an ordinary one. We first derive the phase diagram spanned by the mass term m, chemical potential \ensuremathμ, and strength of the disorder within the self-consistent Born approximation. By way of this, we find a finite density of state appears even at zero energy and at the phase-transition point, i.e., m=\ensuremathμ=0, if the strength of the disorder potential exceeds some critical value. To infer the structure of the low-energy effective theory around these zero-energy states, we further calculated the weak-localization correction to the conductivity. To be more specific, we have found that the diffuson is dominated by the charge diffusion mode and parity diffusion mode. While the charge diffusion mode always carries the diffusion pole, the parity diffusion mode becomes massless only at m=0, but suffers from the infrared cutoff for nonzero m. Corresponding to this feature of the diffuson, the Cooperon is also composed of two quasidegenerate contributions. We found that these two give rise to the same magnitude of the anti-weak-localization (AWL) correction with each other at m=0. As a result, when the topological mass m is fine tuned to be zero (but for generic \ensuremathμ), the AWL correction becomes doubled (quantum correction doubling). Based on this observation, we will discuss the possible microscopic picture of the ``levitation and pair-annihilation'' phenomena, recently discovered by Onoda et al. [Phys. Rev. Lett. 98, 076802 (2007)].