Experimental Observation of Temperature-Driven Topological Phase Transition in HgTe/CdHgTe Quantum Wells

We report on the comparison between temperature-dependent magneto-absorption and magnetotransport spectroscopy of HgTe/CdHgTe quantum wells in terms of the detection of the phase transition between the topological insulator and band insulator states. Our results demonstrate that temperature-dependent magnetospectroscopy is a powerful tool to discriminate trivial and topological insulator phases, yet the magnetotransport method is shown to have advantages for the clear manifestation of the phase transition with accurate quantitative values of the transition parameter (i.e., critical magnetic field Bc).

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Experimental Observation of Temperature-Driven Topological Phase Transition in HgTe/CdHgTe Quantum Wells

10.20944/preprints201901.0295.v1 ◽

2019 ◽

Author(s):

Maksim Zholudev ◽

Aleksandr Kadykov ◽

Mikhail Fadeev ◽

Michal Marcinkiewicz ◽

Sandra Ruffenach ◽

...

Keyword(s):

Magnetic Field ◽

Phase Transition ◽

Quantum Wells ◽

Topological Insulator ◽

Critical Magnetic Field ◽

Topological Phase ◽

Temperature Dependent ◽

Transition Parameter ◽

Topological Phase Transition ◽

Band Insulator

We report on comparison between temperature-dependent magneto¬absorption and magnetotransport spectroscopy of HgTe/CdHgTe quantum wells in terms of detection of phase transition between topological insulator and band insulator states. Our results demonstrate that temperature-dependent magnetospectroscopy is a powerful tool to discriminate trivial and topological insulator phases, yet magnetotransport method is shown to have advantages for clear manifestation of the phase transition with accurate quantitative values of transition parameter (i.e. critical magnetic field Bc).

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Transformation of the Topological Phase and the Edge Modes of Double-Bilayer Bismuthene with Inter-Bilayer Spacing

Crystals ◽

10.3390/cryst9050266 ◽

2019 ◽

Vol 9 (5) ◽

pp. 266 ◽

Cited By ~ 1

Author(s):

Huanzhi Hu ◽

Zhibin Shi ◽

Peng Wang ◽

Weiping Zhou ◽

Tai-Chang Chiang ◽

...

Keyword(s):

Phase Transition ◽

Valence Band ◽

Conduction Band ◽

Topological Insulator ◽

First Principles ◽

Topological Phase ◽

First Principles Calculations ◽

Topological Phase Transition ◽

Band Inversion ◽

Band Insulator

The transformations of the topological phase and the edge modes of a double-bilayer bismuthene were investigated with first-principles calculations and Green’s function as the inter-bilayer spacing increased from 0 Å to 10 Å. At a critical spacing of 2 Å, a topological phase transition from a topological insulator to a band insulator resulting from a band inversion between the highest valence band and the second lowest conduction band, was observed, and this was understood based on the particular orbital characters of the band inversion involved states. The edge modes of double-bilayer bismuthene survived the phase transition. When d was 2 Å < d < 4 Å, the interaction between the edge modes of two separated bismuthene bilayers induced an anti-crossing gap and resulted in a trivial band connection. At and beyond 4 Å, the two bilayers behavior decoupled entirely. The results demonstrate the transformability of the topological phase and the edge modes with the inter-bilayer spacing in double-bilayer bismuthene, which may be useful for spintronic applications.

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