Quantum Transport and Non-Hermiticity on Flat-Band Lattices

We investigate quantum transport in a flat-band lattice induced in a twisted cross-stitch lattice with Hermitian or non-Hermitian potentials, with a combination of parity and time-reversal symmetry invariant. In the given system, the transmission probability demonstrates a resonant behavior on the r...

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Bibliographic Details
Published inJournal of low temperature physics Vol. 191; no. 1-2; pp. 49 - 60
Main Authors Park, Hee Chul, Ryu, Jung-Wan, Myoung, Nojoon
Format Journal Article
LanguageEnglish
Published New York Springer US 01.04.2018
Springer Nature B.V
Subjects
Breaking
Characterization and Evaluation of Materials
Condensed Matter Physics
CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
Energy bands
FUNCTIONS
Lattices
Lifts
Low temperature physics
Magnetic Materials
Magnetism
PARITY
Physics
Physics and Astronomy
POTENTIALS
PROBABILITY
Quantum transport
SPACE
SYMMETRY
Flat bands
Non-Hermiticity
Quantum transport
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Summary:We investigate quantum transport in a flat-band lattice induced in a twisted cross-stitch lattice with Hermitian or non-Hermitian potentials, with a combination of parity and time-reversal symmetry invariant. In the given system, the transmission probability demonstrates a resonant behavior on the real part of the energy bands. Both of the potentials break the parity symmetry, which lifts the degeneracy of the flat and dispersive bands. In addition, non-Hermiticity conserving PT-symmetry induces a transition between the unbroken and broken PT-symmetric phases through exceptional points in momentum space. Characteristics of non-Hermitian and Hermitian bandgaps are distinguishable: The non-Hermitian bandgap is induced by separation toward complex energy, while the Hermitian bandgap is caused by the expelling of available states into real energy. Deviation of the two bandgaps follows as a function of the quartic power of the induced potential. It is notable that non-Hermiticity plays an important role in the mechanism of generating a bandgap distinguishable from a Hermitian bandgap.
ISSN:0022-2291
1573-7357
DOI:10.1007/s10909-017-1848-1