Abstract
The emergence of saddle-point Van Hove singularities (VHSs) in the density of states, accompanied by a change in Fermi surface topology, Lifshitz transition, constitutes an ideal ground for the emergence of different electronic phenomena, such as superconductivity, pseudo-gap, magnetism, and density waves. However, in most materials the Fermi level, {E}_{{rm{F}}}, is too far from the VHS where the change of electronic topology takes place, making it difficult to reach with standard chemical doping or gating techniques. Here, we demonstrate that this scenario can be realized at the interface between a Mott insulator and a band insulator as a result of quantum confinement and correlation enhancement, and easily tuned by fine control of layer thickness and orbital occupancy. These results provide a tunable pathway for Fermi surface topology and VHS engineering of electronic phases.
Highlights
The emergence of saddle-point Van Hove singularities (VHSs) in the density of states, accompanied by a change in Fermi surface topology, Lifshitz transition, constitutes an ideal ground for the emergence of different electronic phenomena, such as superconductivity, pseudo-gap, magnetism, and density waves
One notable example is the emergence of electron liquid behavior, created by novel charge mismatch in the quantum well of nonpolar band insulator SrTiO3 embedded in polar Mott insulator, such as SmTiO3, showing hallmarks of strongly correlated phases, including non-Fermi liquid behavior[15,16], transport lifetime separation[16], pseudogap[17], spin density waves[15], and antiferromagnetism[18]
As the critical thickness is approached[15,16], we reveal the formation of a Van Hove singularity (VHS), a change of orbital character and Fermi surface topology, reminiscent of a Lifshitz transition
Summary
The emergence of saddle-point Van Hove singularities (VHSs) in the density of states, accompanied by a change in Fermi surface topology, Lifshitz transition, constitutes an ideal ground for the emergence of different electronic phenomena, such as superconductivity, pseudo-gap, magnetism, and density waves. The peak positions of MDC (red dots in Fig. 3n, o, q) and energy-distribution curve (EDC) (light-blue dots in Fig. 3n–r) reveal electron- and hole-like dispersion at the X point.
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