Related Experiment Video
Updated: Jun 3, 2026
08:55
Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
Temperature-dependent Raman study of a CeFeAsO(0.9)F(0.1) superconductor: crystal field excitations, phonons and
Pradeep Kumar1, Anil Kumar, Surajit Saha
1Department of Physics, Indian Institute of Science, Bangalore, India.
Summary
This study reveals strong electron-phonon coupling in CeFeAsO(0.9)F(0.1) superconductors. Phonon softening below the critical temperature indicates coupling with the superconducting gap, suggesting a strong coupling mechanism.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Spectroscopy
Background:
- Understanding electron-phonon interactions is crucial for elucidating superconductivity mechanisms.
- Cerium fluorooxypnictides (CeFeAsO1-xFx) are a class of materials exhibiting complex electronic properties.
Purpose of the Study:
- To investigate the temperature-dependent Raman spectra of CeFeAsO(0.9)F(0.1).
- To explore the coupling between phonons, crystal field excitations, and the superconducting gap.
Main Methods:
- Temperature-dependent Raman spectroscopy (4-300 K).
- First-principles density functional calculations for phonon frequencies.
- Analysis of spectral features and mode couplings.
Main Results:
- Strong coupling observed between phonons and Ce(3+) crystal field excitations.
- A phonon mode near 280 cm(-1) softens below Tc, indicating coupling with the superconducting gap.
- Electronic Raman scattering attributed to Fe d-orbitals observed at high frequencies.
Conclusions:
- CeFeAsO(0.9)F(0.1) is identified as a strong coupling superconductor.
- The results provide insights into the interplay of electronic and vibrational degrees of freedom in iron-based superconductors.
Related Concept Videos
01:27Atomic Spectroscopy: Effects of Temperature
Atomization, converting samples into gas-phase atoms and ions, is essential for atomic spectroscopy. The flame temperature required for atomization affects the efficiency of the atomic spectroscopic methods by increasing the atomization efficiency and the relative population of the excited and ground states.
At thermal equilibrium, the relative populations of excited and ground state atoms can be estimated using the Maxwell–Boltzmann distribution. For example, an increase in temperature from...
At thermal equilibrium, the relative populations of excited and ground state atoms can be estimated using the Maxwell–Boltzmann distribution. For example, an increase in temperature from...
01:24Superconductor
A substance that reaches superconductivity, a state in which magnetic fields cannot penetrate, and there is no electrical resistance, is referred to as a superconductor. In 1911, Heike Kamerlingh Onnes of Leiden University, a Dutch physicist, observed a relation between the temperature and the resistance of the element mercury. The mercury sample was then cooled in liquid helium to study the linear dependence of resistance on temperature. It was observed that, as the temperature decreased, the...
01:26Raman Spectroscopy Instrumentation: Overview
A conventional Raman spectrophotometer includes a laser source, a sample holding system, a wavelength selector, and a detector.
The monochromatic laser source, typically using visible or near-infrared radiation, generates a highly focused beam of light. This light interacts with the molecules of the sample, scattering some of the light. Liquid and gaseous samples are usually tested in ordinary glass capillaries, while solids can be analyzed as powders packed in capillaries or as potassium...
The monochromatic laser source, typically using visible or near-infrared radiation, generates a highly focused beam of light. This light interacts with the molecules of the sample, scattering some of the light. Liquid and gaseous samples are usually tested in ordinary glass capillaries, while solids can be analyzed as powders packed in capillaries or as potassium...
01:31Ferromagnetism
Materials like iron, nickel, and cobalt consist of magnetic domains, within which the magnetic dipoles are arranged parallel to each other. The magnetic dipoles are rigidly aligned in the same direction within a domain by quantum mechanical coupling among the atoms. This coupling is so strong that even thermal agitation at room temperature cannot break it. The result is that each domain has a net dipole moment. However, some materials have weaker coupling, and are ferromagnetic at lower...
01:20Raman Spectroscopy: Overview
The underlying principle of Raman spectroscopy is based on the interaction between light and matter, specifically molecules' inelastic scattering of photons. When a monochromatic beam of light, typically from a laser source, interacts with a sample, most scattered light has the same frequency as the incident light. This is known as Rayleigh scattering.
However, a small fraction of the scattered light exhibits a frequency shift due to the exchange of energy between the incident photons and the...
However, a small fraction of the scattered light exhibits a frequency shift due to the exchange of energy between the incident photons and the...
01:17Theory of Metallic Conduction
The conduction of free electrons inside a conductor is best described by quantum mechanics. However, a classical model makes predictions close to the results of quantum mechanics. It is called the theory of metallic conduction.
In this theory, Newton's second law of motion is used to determine the acceleration of an electron in the presence of an applied electric field. Then, its velocity is expressed via this acceleration.
An electron moves through the crystal, containing positive ions,...
In this theory, Newton's second law of motion is used to determine the acceleration of an electron in the presence of an applied electric field. Then, its velocity is expressed via this acceleration.
An electron moves through the crystal, containing positive ions,...