Anomalous Spin Response and Virtual-Carrier-Mediated Magnetism in a Topological Insulator

Abstract

We present a comprehensive theoretical study of the static spin response in HgTe quantum wells, revealing distinctive behavior for the topologically nontrivial inverted structure. Most strikingly, the q=0 (long-wave-length) spin susceptibility of the undoped topological-insulator system is constant and equal to the value found for the gapless Dirac-like structure, whereas the same quantity shows the typical decrease with increasing band gap in the normal-insulator regime. We discuss ramifications for the ordering of localized magnetic moments present in the quantum well, both in the insulating and electron-doped situations. The spin response of edge states is also considered, and we extract effective Lande g-factors for the bulk and edge electrons. The variety of counter-intuitive spin-response properties revealed in our study arises from the system's versatility in accessing situations where the charge-carrier dynamics can be governed by ordinary Schrodinger-type physics, mimics the behavior of chiral Dirac fermions, or reflects the material's symmetry-protected topological order.

15 pages, 8 figures, RevTex4.1; v2: extended and expanded results and presentation

References in corpus (14)

• Quantum Spin Hall Effect and Topological Phase Transition in HgTe Quantum Wells
• Quantum Spin Hall Insulator State in HgTe Quantum Wells
• Quantized Anomalous Hall Effect in Magnetic Topological Insulators
• Nonlocal edge state transport in the quantum spin Hall state
• The Quantum Spin Hall Effect: Theory and Experiment
• Quantum Spin Hall Effect in Inverted Type II Semiconductors
• Quantum Anomalous Hall Effect in Hg${}_{1-y}$Mn${}_y$Te Quantum Wells
• Finite size effects of helical edge states in HgTe/CdTe quantum wells
• Edge-mode Superconductivity in a Two Dimensional Topological Insulator
• Pauli spin susceptibility of a strongly correlated two-dimensional electron liquid
• Spin Orientation of Holes in Quantum Wells
• Magnetic Ordering of Nuclear Spins in an Interacting 2D Electron Gas
• Screening properties and plasmons of Hg(Cd)Te quantum wells
• Carrier-density-controlled anisotropic spin susceptibility of two-dimensional hole systems

Cited by in corpus (6)

• Realistic picture of helical edge states in HgTe quantum wells
• Indirect exchange interaction between magnetic impurities near the helical edge
• Indirect exchange interaction between magnetic impurities in the two-dimensional topological insulator based on CdTe/HgTe/CdTe quantum wells
• Quantum capacitance of an HgTe quantum well as an indicator of the topological phase
• Spin Stiffness and Domain Walls in Dirac-Electron Mediated Magnets
• Semiclassical scattering by edge imperfections in topological insulators under magnetic field