Related Experiment Video
Updated: Aug 7, 2026
08:01
Spectral and Angle-Resolved Magneto-Optical Characterization of Photonic Nanostructures
Published on: November 21, 2019
Magnetic circular dichroism near the Fermi level
Takeshi Nakagawa1, Toshihiko Yokoyama
1Department of Molecular Structure, Institute for Molecular Science, and Department of Structural Molecular Science, The Graduate University for Advanced Studies (Sokendai), Myodaiji-cho, Okazaki, 444-8585, Japan.
Physical Review Letters
|June 29, 2006
Summary
Researchers observed enhanced magnetic circular dichroism (MCD) near the Fermi level in ultrathin magnetic films. Perpendicularly magnetized nickel films showed over 10% MCD asymmetry, significantly influenced by work function changes.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Surface Science
Background:
- Magnetic Circular Dichroism (MCD) is a sensitive probe of magnetic properties.
- Understanding MCD in ultrathin films is crucial for spintronics and magnetic data storage.
- Previous studies have explored MCD in various magnetic materials, but enhancement near the Fermi level requires further investigation.
Purpose of the Study:
- To investigate the phenomenon of enhanced magnetic circular dichroism (MCD) near the Fermi level in ultrathin magnetic films.
- To explore the influence of work function modification on MCD asymmetry.
- To compare MCD asymmetry in perpendicularly versus in-plane magnetized films.
Main Methods:
- Utilized visible and ultraviolet lasers for MCD measurements.
- Investigated ultrathin films of Ni, Co, and Fe on Cu(001) substrates.
- Employed cesium adsorption to modify the work function of the films.
- Performed theoretical calculations to support experimental observations.
Main Results:
- Achieved over 10% MCD asymmetry for a 12 ML Ni film on Cu(001) with perpendicular magnetization.
- Observed enhanced MCD asymmetry near the photoemission threshold, which decreased significantly with increasing photon energy.
- Demonstrated that perpendicularly magnetized films exhibit substantially larger MCD asymmetries compared to in-plane magnetized films.
Conclusions:
- The study confirms enhanced MCD near the Fermi level, particularly near the photoemission threshold, in ultrathin magnetic films.
- Work function modification plays a critical role in tuning MCD asymmetry.
- Perpendicular magnetic anisotropy is key to achieving large MCD signals in these systems.
Related Concept Videos
01:27π Electron Effects on Chemical Shift: Overview
An applied magnetic field causes loosely bound π-electrons in organic molecules to circulate, producing a local or induced diamagnetic field over a large spatial volume. As the molecules tumble in solution, the field generated by π-electrons in spherical substituents results in a zero net field. However, the net field generated by π-electrons in non-spherical substituents is not zero. The effect of this induced field depends on the orientation of the molecule with respect to B0, resulting in...
01:26Diamagnetism
Materials consisting of paired electrons have zero net magnetic moments. However, when these materials are placed under an external magnetic field, the moments opposite to the field are induced. Such materials are called diamagnets. Diamagnetism is the response of the diamagnets when placed in an external magnetic field.
Diamagnetism was discovered by Anton Brugmans in 1778 when he observed that bismuth gets repelled by magnetic fields, thus theorizing that diamagnets get repelled by magnets.
Diamagnetism was discovered by Anton Brugmans in 1778 when he observed that bismuth gets repelled by magnetic fields, thus theorizing that diamagnets get repelled by magnets.
01:14π Electron Effects on Chemical Shift: Aromatic and Antiaromatic Compounds
In aromatic compounds, such as benzene, the circulation of (4n + 2) π-electrons sets up a diamagnetic or diatropic ring current around the perimeter of the molecule. This current induces a magnetic field that opposes the external field inside the ring and reinforces it on the outside. The protons in benzene are deshielded and exhibit high chemical shifts in the range 6.5–8.5 ppm. The shielding effect at the center of the ring is evident in complex aromatic molecules, such as annulenes. In...
03:02Colors and Magnetism
Color in Coordination Complexes
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
01:18Fermi Level
The Fermi-Dirac function is represented by an S-shaped curve indicating the probability of an energy state being occupied by an electron at a given temperature. The Fermi level is the energy level at which there is a fifty percent chance of finding an electron, and it is positioned between the lower-energy valence band and the higher-energy conduction band.
At absolute zero temperature, electrons fill all energy states up to the Fermi level, leaving upper states empty. As the temperature rises,...
At absolute zero temperature, electrons fill all energy states up to the Fermi level, leaving upper states empty. As the temperature rises,...
01:23Atomic Nuclei: Nuclear Relaxation Processes
In the absence of an external magnetic field, nuclear spin states are degenerate and randomly oriented. When a magnetic field is applied, the spins begin to precess and orient themselves along (lower energy) or against (higher energy) the direction of the field. At equilibrium, a slight excess population of spins exists in the lower energy state. Because the direction of the magnetic field is fixed as the z-axis, the precessing magnetic moments are randomly oriented around the z-axis. This...