Abstract
We report terahertz measurements on bulk HgCdTe crystals at the semiconductor- to-semimetal topological transition and InAs/GaSb inverted band structure quantum well. We show that physical parameters of these narrow gap systems driven in specific topological phases can be efficiently extracted by means of terahertz photoconductivity studies.
Highlights
In the past years, the discovery of novel topological states of matter has attracted significant attention [1]
As the Cd composition increases, the energy gap increases from a negative value for pure HgTe to a positive one with CdTe
In contrast to measurements at T = 77K consecutive illuminations decreased the conductivity – the sample exhibited the NPPC effect. Those results are consistent with those obtained in [12], except that the change between PPPC and NPPC occurred at different temperature
Summary
The discovery of novel topological states of matter has attracted significant attention [1]. In InAs/GaSb BGQW, the energy of the valence band edge of GaSb is higher tens of meV) than the conduction band edge of InAs – the structure exhibits semimetallic behaviour.
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