75As NMR studies of superconducting LaFeAsO0.9F0.1
1IFW Dresden, Institute for Solid State Research, P.O. Box 270116, D-01171 Dresden, Germany.
Physical Review Letters
|September 4, 2008
Summary
Nuclear magnetic resonance measurements on LaFeAsO0.9F0.1 reveal line nodes in the superconducting gap and spin-singlet pairing. Anisotropy suggests superconducting vortices influence relaxation rates, particularly along the c axis.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Superconductivity
Background:
- LaFeAsO0.9F0.1 is a novel superconductor.
- Understanding its electronic properties is crucial for advancing high-temperature superconductivity research.
Purpose of the Study:
- To investigate the electronic properties of LaFeAsO0.9F0.1 using nuclear magnetic resonance (NMR).
- To determine the nature of the superconducting gap and pairing symmetry.
Main Methods:
- Performed 75As nuclear magnetic resonance (NMR) measurements.
- Utilized aligned powders of LaFeAsO0.9F0.1 superconductor.
- Analyzed spin shift and spin lattice relaxation rate in both normal and superconducting states.
Main Results:
- Observed strong temperature dependence of spin shift and Korringa behavior in the normal state.
- Found evidence for line nodes in the superconducting gap and spin-singlet pairing.
- Detected strong anisotropy in the spin lattice relaxation rate.
Conclusions:
- The results indicate the presence of line nodes and spin-singlet pairing in LaFeAsO0.9F0.1.
- Anisotropic spin lattice relaxation suggests superconducting vortices contribute to relaxation when the magnetic field is parallel to the c axis.
More Related Videos
09:06Visualizing Uniaxial-strain Manipulation of Antiferromagnetic Domains in Fe1+YTe Using a Spin-polarized Scanning Tunneling Microscope
Published on: March 24, 2019
06:49Radio Frequency Magnetron Sputtering of GdBa2Cu3O7−δ/ La0.67Sr0.33MnO3 Quasi-bilayer Films on SrTiO3 (STO) Single-crystal Substrates
Published on: April 12, 2019
Related Concept Videos
01:28Types Of Superconductors
A superconductor is a substance that offers zero resistance to the electric current when it drops below a critical temperature. Zero resistance is not the only interesting phenomenon as materials reach their transition temperatures. A second effect is the exclusion of magnetic fields. This is known as the Meissner effect. A light, permanent magnet placed over a superconducting sample will levitate in a stable position above the superconductor. High-speed trains that levitate on strong...
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...
01:31Ferromagnetism
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...
01:08NMR Spectroscopy: Spin–Spin Coupling
The spin state of an NMR-active nucleus can have a slight effect on its immediate electronic environment. This effect propagates through the intervening bonds and affects the electronic environments of NMR-active nuclei up to three bonds away; occasionally, even farther. This phenomenon is called spin–spin coupling or J-coupling. Coupling interactions are mutual and result in small changes in the absorption frequencies of both nuclei involved. While nuclei of the same element are involved in...
01:31Magnetic Susceptibility and Permeability
In linear magnetic materials, like paramagnets and diamagnets, magnetization is proportional to the magnetic field intensity. The constant of proportionality, a dimensionless number, is called magnetic susceptibility. The value of the susceptibility depends on the type of material.
When diamagnetic materials are placed under an external magnetic field, the moments opposite to the field are induced. Hence, the susceptibility for diamagnets has a minimal negative value of 10-5–10-6. Since...
When diamagnetic materials are placed under an external magnetic field, the moments opposite to the field are induced. Hence, the susceptibility for diamagnets has a minimal negative value of 10-5–10-6. Since...
01:11Atomic Nuclei: Larmor Precession Frequency
The earth's gravitational field produces a 'twisting force' perpendicular to the angular momentum of a spinning mass (such as a spinning top) that causes the mass to 'wobble' around the gravitational field axis in a phenomenon called precession. Similarly, the magnetic moment (μ) of a spinning nucleus precesses due to an external magnetic field directed along the z-axis. The precession of the magnetic moment vector about the magnetic field is called Larmor precession, and the angular frequency...