Research

— The da Silva Neto Lab focuses on experiments that investigate the electronic properties of quantum materials. These are materials that under special conditions develop exotic electronic quantum phases of matter, such as pair-density-waves, nematic order, topological superconductivity and novel Majorana modes. Quantum materials (e.g. graphene, topological insulators, quantum spin liquids, and superconductors) are solid-state systems that feature poorly understood exotic electronic quantum phases of matter. Although all materials require quantum mechanics to explain their properties, quantum materials develop actually tangible emergent quantum effects. These exciting effects include the realization of exotic emergent topological particles (Weyl and Majorana states) and unconventional superconductivity intertwined with charge and spin order, which may provide new avenues for next-generation quantum computation and energy efficient materials. My research currently focuses on the study of topological materials and unconventional superconductors. To study the basic quantum mechanics of these materials my group uses a suite of techniques. First, at Yale, we will employ low-temperature (sub 1K) and high magnetic field (11T) scanning tunneling microscopy and spectroscopy (STM/S) to visualize the quantum wave functions of electrons at the atomic scale. Second, to complement the STM/S real-space studies at Yale, we will measure the electronic states in reciprocal space at synchrotron facilities around the globe, primarily using resonant soft x-ray scattering (RXS) and angle-resolved photoemission spectroscopy (ARPES) experiments. Current projects include the study of pair-density waves in heavy-fermion superconductors, the investigation of superconductivity and Fe-based high-temperature superconductors and their relationship to rotational symmetry breaking, and the search for new topological superconductors.For an overview regarding the experimental techniques we use, see this talk (after the introduction in Portuguese the talk is given in English):

https://www.youtube.com/watch?v=ncHuDRm9YCE

RXS: Crystallography and Reciprocal Space

Condensed Matter Concepts: Metals and Insulators, Graphene and Dirac Cones

Schematic of an STM. A sharp metallic tip (red) is brought in close proximity (~1-5 Angstroms) to the material to be studied. Quantum tunneling of the electrons through the vacuum barrier, in tandem with a precise scanning motion of the tip above the surface, allows the electronic states to be visualized.

Helium Recovery System

Scanning Tunneling Microscope

Microscopy

Charge order in the hole-doped cuprate high-temperature superconductor Bi2Sr2CaCu2O8+x visualized in real space (front) using a scanning tunneling microscope, or in reciprocal space (back) using resonant X-ray scattering (green arrows). From E. H. da Silva Neto, et al. Science 343, 393 (2014).

Quasiparticle Interference (QPI) measured at the UC Davis STM/S Lab.

For more details see the following review articles:

STM/S: A. Yazdani, E. H. da Silva Neto, and P. Aynajian – Spectroscopic imaging of strongly correlated electronic states. Annual Review of Condensed Matter Physics 7, 11-33 (2016).

RXS: J. Fink, E. Schierle, E. Weschke and J. Geck – Resonant elastic soft x-ray scattering. Reports on Progress in Physics, Volume 76, Number 5 (2013).

ARPES: Andrea Damascelli, Zahid Hussain, and Zhi-Xun Shen – Angle-resolved photoemission studies of the cuprate superconductors. Review of Modern Physics 75, 473 (2003)

ARPES: Jonathan A. Sobota, Yu He, and Zhi-Xun Shen – Angle-resolved photoemission studies of quantum materials. Review of Modern Physics 93, 025006 (2021).