130 research outputs found
Gate-electric-field and magnetic-field control of versatile topological phases in a semi-magnetic topological insulator
Surface states of a topological insulator demonstrate interesting quantum
phenomena, such as the quantum anomalous Hall (QAH) effect and the quantum
magnetoelectric effect. Fermi energy tuning plays a role in inducing phase
transitions and developing future device functions. Here, we report on
controlling the topological phases in a dual-gate field-effect transistor of a
semi-magnetic topological insulator heterostructure. The heterostructure
consists of magnetized one-surface and non-magnetic other-surface. By tuning
the Fermi energy to the energy gap of the magnetized surface, the Hall
conductivity becomes close to the half-integer quantized Hall
conductivity , exemplifying parity anomaly. The dual-gate control
enables the band structure alignment to the two quantum Hall states with
and 0 under a strong magnetic field. These states are
topologically equivalent to the QAH and axion insulator states, respectively.
Precise and independent control of the band alignment of the top and bottom
surfaces successively induces various topological phase transitions among the
QAH, axion insulator, and parity anomaly states in magnetic topological
insulators.Comment: 20 pages, 4 figure
Update of : Newly added functions and methods in versions 2 and 3
[-] is an open-source software package of
numerically exact and stochastic calculations for a wide range of quantum
many-body systems. In this paper, we present the newly added functions and the
implemented methods in vers. 2 and 3. In ver. 2, we implement spectrum
calculations by the shifted Krylov method, and low-energy excited state
calculations by the locally optimal blocking preconditioned conjugate gradient
(LOBPCG) method. In ver. 3, we implement the full diagonalization method using
ScaLAPACK and GPGPU computing via MAGMA. We also implement a real-time
evolution method and the canonical thermal pure quantum (cTPQ) state method for
finite-temperature calculations. The Wannier90 format for specifying the
Hamiltonians is also implemented. Using the Wannier90 format, it is possible to
perform the calculations for the low-energy effective
Hamiltonians of solids obtained by the open-source software RESPACK. We also
update Standard mode \unicode{x2014}simplified input format in
\unicode{x2014} to use these functions and methods. We
explain the basics of the implemented methods and how to use them.Comment: 21 pages, 10 figures, 2 table
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