Abstract
Layered transition metal chalcogenides are promising hosts of electronic Weyl nodes and topological superconductivity. MoTe2 is a striking example that harbors both noncentrosymmetric Td and centrosymmetric T’ phases, both of which have been identified as topologically nontrivial. Applied pressure tunes the structural transition separating these phases to zero temperature, stabilizing a mixed Td–T’ matrix that entails a network of interfaces between the two nontrivial topological phases. Here, we show that this critical pressure range is characterized by distinct coherent quantum oscillations, indicating that the difference in topology between topologically nonvtrivial Td and T’ phases gives rise to an emergent electronic structure: a network of topological interfaces. A rare combination of topologically nontrivial electronic structures and locked-in transformation barriers leads to this counterintuitive situation, wherein quantum oscillations can be observed in a structurally inhomogeneous material. These results further open the possibility of stabilizing multiple topological phases coexisting with superconductivity.
Highlights
Protected electronic states at material interfaces are attractive because they cannot be destroyed by many types of perturbations[1,2]
Essential to any topological surface state is the meeting of two bulk phases with different topological invariants
A typical example is that of a Weyl semimetal interfaced with a topologically trivial vacuum, on whose boundary Fermi arcs are observed, as in Td–MoTe28
Summary
Protected electronic states at material interfaces are attractive because they cannot be destroyed by many types of perturbations[1,2]. MoTe2 features topologically nontrivial normal states: the Td phase has been identified as a type II Weyl semimetal[7,8,9,10], whereas the monoclinic T’ phase is predicted to be a higher-order topological material[11]; the latter is found to describe the Td phase in some calculations[11]. We demonstrate via quantum oscillations and neutron scattering measurements, and first-principles calculations, how pressure drives MoTe2 between the Td and T’ phases, through an intermediate mixed-phase region. The mixed-phase region gives rise to a network of topological interface states that yield quantum oscillations that survive despite the strong structural disorder
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