Related Experiment Video
Updated: May 24, 2026
06:49
Radio Frequency Magnetron Sputtering of GdBa2Cu3O7−δ/ La0.67Sr0.33MnO3 Quasi-bilayer Films on SrTiO3 (STO) Single-crystal Substrates
Published on: April 12, 2019
Low-field magnetoresistance effect in core-shell structured La(0.7) Sr(0.3) CoO(3) nanoparticles
1Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371 Singapore, Singapore. wangyanghit@gmail.com
Small (Weinheim an Der Bergstrasse, Germany)
|February 15, 2012
Summary
Core-shell lanthanum strontium cobalt oxide nanoparticles exhibit enhanced low-field magnetoresistance. The insulating shells improve spin-polarized tunneling between ferromagnetic cores, boosting magnetoresistance effects.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Nanotechnology
Background:
- Lanthanum strontium cobalt oxide (La(0.7)Sr(0.3)CoO(3)) is a perovskite material with interesting magnetic properties.
- Core-shell nanostructures offer unique properties due to the combination of different materials and morphologies.
Purpose of the Study:
- To synthesize core-shell structured La(0.7)Sr(0.3)CoO(3) nanoparticles.
- To investigate the magnetic and magneto-transport properties of these nanoparticles.
- To understand the role of the core-shell structure in enhancing magnetoresistance.
Main Methods:
- Synthesis of core-shell structured La(0.7)Sr(0.3)CoO(3) nanoparticles.
- Characterization of magnetic properties.
- Investigation of magneto-transport properties, including magnetoresistance measurements.
Main Results:
- Successfully synthesized core-shell La(0.7)Sr(0.3)CoO(3) nanoparticles with single-crystalline, ferromagnetic cores and noncrystalline, paramagnetic shells.
- Identified the insulating-like shells as effective spin tunneling barriers.
- Observed improved spin-polarized interparticle tunneling due to the shell's presence.
Conclusions:
- The core-shell structure significantly enhances the low-field magnetoresistance effect in La(0.7)Sr(0.3)CoO(3) nanoparticles.
- The interplay between ferromagnetic cores and insulating shells is crucial for improved spin tunneling and magnetoresistance.
- These findings suggest potential applications in magnetic sensors and spintronic devices.
Related Concept Videos
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...
01:31Magnetic 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...
01:14Diamagnetic Shielding of Nuclei: Local Diamagnetic Current
An applied magnetic field causes the electrons present in the molecule to circulate, setting up a local diamagnetic current within the molecule. The local diamagnetic current arising from circulating sigma-bonding electrons induces a magnetic field, Blocal that opposes the applied magnetic field, B0. The effective magnetic field experienced by these nuclei is given by the difference between the applied and local magnetic fields in a phenomenon called local diamagnetic shielding. Essentially,...
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.
01:23Magnetic Field due to Moving Charges
A stationary charge creates and interacts with the electric field, while a moving charge creates a magnetic field.
Consider a point charge moving with a constant velocity. Like the electric field, the magnetic field at any point is directly proportional to the magnitude of the charge and inversely proportional to the square of the distance between the source point and the field point. However, unlike the electric field, the magnetic field is always perpendicular to the plane containing the line...
Consider a point charge moving with a constant velocity. Like the electric field, the magnetic field at any point is directly proportional to the magnitude of the charge and inversely proportional to the square of the distance between the source point and the field point. However, unlike the electric field, the magnetic field is always perpendicular to the plane containing the line...
01:30Paramagnetism
Paramagnets are materials with unpaired electrons that possess a finite magnetic moment. In the absence of a magnetic field, these moments are randomly oriented, and thus the net moment is zero. Under an external field, a torque acting on the moments tends to align them along the field's direction. However, the random thermal motion of electrons produces a torque opposite to the external field and tries to disorient the moments. These two competing effects align only a few moments along the...