Direct observation and temperature control of the surface Dirac gap in the topological crystalline insulator (Pb,Sn)Se

Abstract

Since the advent of topological insulators hosting symmetry-protected Dirac surface states, efforts have been made to gap these states in a controllable way. A new route to accomplish this was opened up by the discovery of topological crystalline insulators (TCIs) where the topological states are protected by real space crystal symmetries and thus prone to gap formation by structural changes of the lattice. Here, we show for the first time a temperature-driven gap opening in Dirac surface states within the TCI phase in (Pb,Sn)Se. By using angle-resolved photoelectron spectroscopy, the gap formation and mass acquisition is studied as a function of composition and temperature. The resulting observations lead to the addition of a temperature- and composition-dependent boundary between massless and massive Dirac states in the topological phase diagram for (Pb,Sn)Se (001). Overall, our results experimentally establish the possibility to tune between a massless and massive topological state on the surface of a topological system.

5 pages, 3 figures

References in corpus (5)

• Topological Crystalline Insulators
• Topological Crystalline Insulators and Topological Superconductors: From Concepts to Materials
• Dirac mass generation from crystal symmetry breaking on the surfaces of topological crystalline insulators
• Spin-polarized (001) surface states of the topological crystalline insulator Pb_{0.73}Sn_{0.27}Se
• Observation of Topological Crystalline Insulator phase in the lead tin chalcogenide Pb1-xSnxTe material class

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