Related Experiment Video
Updated: May 7, 2025
13:56
Probe Type II Band Alignment in One-Dimensional Van Der Waals Heterostructures Using First-Principles Calculations
Published on: October 12, 2019
7.5K
Local correlations necessitate waterfalls as a connection between quasiparticle band and developing Hubbard bands
Juraj Krsnik1,2, Karsten Held3
1Institute of Solid State Physics, TU Wien, 1040, Vienna, Austria. juraj.krsnik@tuwien.ac.at.
Nature Communications
|January 2, 2025
Summary
Waterfalls in angle-resolved photoemission spectra are naturally explained by the development of a Hubbard band splitting from the quasiparticle band, not just boson coupling. This finding applies to correlated materials like cuprates and nickelates.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Quantum Chemistry
Background:
- Waterfalls are spectral anomalies in angle-resolved photoemission spectroscopy (ARPES) characterized by vertical energy-momentum dispersion and significant spectral broadening.
- These phenomena are observed at high energies in strongly correlated materials, notably superconducting cuprates and nickelates.
- Current theories attribute waterfalls to coupling with bosonic excitations, such as spin fluctuations or phonons.
Purpose of the Study:
- To investigate an alternative mechanism for the formation of waterfalls in ARPES spectra.
- To demonstrate that Hubbard band development can naturally produce waterfall anomalies.
- To provide a new theoretical framework for understanding spectral anomalies in correlated electron systems.
Main Methods:
- Utilized the Hubbard model with ab initio determined parameters.
- Simulated the angle-resolved photoemission spectrum within this model.
- Analyzed the energy-momentum dispersion and spectral functions to identify waterfall features.
Main Results:
- Showed that waterfalls emerge naturally from the development and splitting of a Hubbard band from the quasiparticle band.
- The simulated spectra align well with experimental observations of waterfalls in cuprates and nickelates.
- This provides a compelling explanation without invoking external bosonic couplings.
Conclusions:
- The coupling to bosons is not the sole or necessary explanation for waterfalls in ARPES.
- Hubbard band formation offers a natural and consistent explanation for these spectral anomalies.
- This work reframes the understanding of electronic correlations and their signatures in photoemission spectroscopy.
Related Concept Videos
01:01Energy Bands in Solids
568
Isolated atoms have discrete energy levels that are well described by the Bohr model. And, it quantifies the energy of an electron in a hydrogen atom as En. Higher quantum numbers 'n' yield less negative, closer electron energy levels.
Band Formation:
When atoms are brought close together, as in a solid, these discrete energy levels begin to split due to the overlap of electron orbitals from adjacent atoms. This split occurs because of the Pauli exclusion principle, which states...
Band Formation:
When atoms are brought close together, as in a solid, these discrete energy levels begin to split due to the overlap of electron orbitals from adjacent atoms. This split occurs because of the Pauli exclusion principle, which states...
568
01:12Fermi Level Dynamics
188
The vacuum level denotes the energy threshold required for an electron to escape from a material surface. It is usually positioned above the conduction band of a semiconductor and acts as a benchmark for comparing electron energies within various materials.
Electron affinity in semiconductors refers to the energy gap between the minimum of its conduction band and the vacuum level and it is a critical parameter in determining how easily a semiconductor can accept additional electrons.
The work...
Electron affinity in semiconductors refers to the energy gap between the minimum of its conduction band and the vacuum level and it is a critical parameter in determining how easily a semiconductor can accept additional electrons.
The work...
188
02:35Band Theory
14.8K
When two or more atoms come together to form a molecule, their atomic orbitals combine and molecular orbitals of distinct energies result. In a solid, there are a large number of atoms, and therefore a large number of atomic orbitals that may be combined into molecular orbitals. These groups of molecular orbitals are so closely placed together to form continuous regions of energies, known as the bands.
The energy difference between these bands is known as the band gap.
Conductor, Semiconductor,...
The energy difference between these bands is known as the band gap.
Conductor, Semiconductor,...
14.8K
02:38Valence Bond Theory and Hybridized Orbitals
18.4K
According to valence bond theory, a covalent bond results when: (1) an orbital on one atom overlaps an orbital on a second atom, and (2) the single electrons in each orbital combine to form an electron pair. The strength of a covalent bond depends on the extent of overlap of the orbitals involved. Maximum overlap is possible when the orbitals overlap on a direct line between the two nuclei.
A σ bond (single bond in a Lewis structure) is a covalent bond in which the electron density is...
A σ bond (single bond in a Lewis structure) is a covalent bond in which the electron density is...
18.4K
02:18Network Covalent Solids
13.2K
Network covalent solids contain a three-dimensional network of covalently bonded atoms as found in the crystal structures of nonmetals like diamond, graphite, silicon, and some covalent compounds, such as silicon dioxide (sand) and silicon carbide (carborundum, the abrasive on sandpaper). Many minerals have networks of covalent bonds.
To break or to melt a covalent network solid, covalent bonds must be broken. Because covalent bonds are relatively strong, covalent network solids are typically...
To break or to melt a covalent network solid, covalent bonds must be broken. Because covalent bonds are relatively strong, covalent network solids are typically...
13.2K
02:54Trends in Lattice Energy: Ion Size and Charge
23.4K
An ionic compound is stable because of the electrostatic attraction between its positive and negative ions. The lattice energy of a compound is a measure of the strength of this attraction. The lattice energy (ΔHlattice) of an ionic compound is defined as the energy required to separate one mole of the solid into its component gaseous ions. For the ionic solid sodium chloride, the lattice energy is the enthalpy change of the process:
23.4K