2015/04/30 by Héctor Ochoa, Hector Ochoa
Physics and Astronomy · #Advanced Condensed Matter Physics #Condensed matter physics #Electron #Magnetic moment #Physics #Quantum many-body systems #Quantum mechanics #Spin magnetic moment #Spin polarization #Topological Materials and Phenomena #Topological insulator #cond-mat.mes-hall #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.92.081410
published as Phys. Rev. B 92, 081410 (2015) · 5 pages, 3 figures; final version to appear in Physical Review B as a rapid communication
arxiv created 2015/08/14 · openalex publication_date 2015/08/25 · arxiv updated 2015/09/02 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We study the exchange interaction and the subsequent collective behavior of magnetic impurities embedded in a disordered two-dimensional helical metal. The exchange coupling follows a statistical distribution whose moments are calculated to the lowest order in (pF\ensuremathℓ)^\ensuremath-1, where pF is the Fermi momentum of itinerant electrons and \ensuremathℓ is the mean free path. We find that (i) the first moment of the distribution decays exponentially, and (ii) the variance of the interaction is long range, however, it becomes independent of the orientation of the localized magnetic moments due to the locking between spin and momentum of the electrons that mediate the interaction. As a consequence, long-range magnetic order tends to be suppressed, and a spin glass phase emerges. The formalism is applied to the surface states of a three-dimensional topological insulator. The lack of a net magnetic moment in the glassy phase and the full randomization of spin polarization at distances larger than \ensuremathℓ excludes a spectral gap for surface states. Hence, nonmagnetic disorder may explain the dispersion in results for photoemission experiments in magnetically doped topological insulators.