Thermoelectric transport in temperature-driven two-dimensional topological insulators.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Phenomena

Background:

• Topological insulators (TIs) possess unique electronic properties with potential applications in advanced electronics.
• Thermoelectric (TE) materials can convert heat energy into electrical energy, crucial for energy harvesting and cooling.
• Understanding the interplay of different electronic states in TIs is key to optimizing their TE performance.

Purpose of the Study:

• To theoretically investigate the thermoelectric transport properties of edge and bulk states in a temperature-driven 2D topological insulator.
• To explore how temperature and chemical potential influence the TE transport characteristics in CdTe/HgTe/CdTe quantum wells.
• To analyze the impact of ribbon width on the thermoelectric figure of merit (ZT) and identify potential bulk-to-edge transitions.

Main Methods:

• Theoretical investigation of thermoelectric transport properties.
• Modeling of a temperature-driven two-dimensional topological insulator in CdTe/HgTe/CdTe quantum wells.
• Analysis of the influence of temperature, chemical potential, and ribbon width on edge and bulk state contributions to TE transport.

Main Results:

• Temperature effectively drives a topological insulator phase in the studied quantum wells.
• Thermoelectric transport is governed by edge states, bulk states, or their interplay, depending on temperature and chemical potential.
• A peak in the thermoelectric figure of merit (ZT) at low temperatures, attributed to bulk-edge transport competition, vanishes at high temperatures due to bulk state dominance.
• Decreasing ribbon width leads to two ZT peaks at low temperatures (bulk-edge competition and edge-edge hybridization) and a high-temperature bulk-to-edge transition in TE transport.

Conclusions:

• The thermoelectric transport properties of temperature-driven 2D TIs are highly tunable via temperature, chemical potential, and structural dimensions.
• The competition and hybridization between bulk and edge states play a critical role in determining the ZT.
• The observed bulk-to-edge transition in TE transport with varying ribbon width highlights the potential for engineering advanced thermoelectric devices based on 2D TIs.