Related Experiment Video
Updated: Jul 7, 2026
10:36
Advanced Experimental Methods for Low-temperature Magnetotransport Measurement of Novel Materials
Published on: January 21, 2016
Sample-size effects in the magnetoresistance of graphite
J C González1, M Muñoz, N García
1Laboratorio de Física de Sistemas Pequeños y Nanotecnología, Consejo Superior de Investigaciones Científicas, E-28006 Madrid, Spain.
Physical Review Letters
|February 1, 2008
Summary
Conduction electrons in graphite exhibit large de Broglie wavelengths and mean free paths. This study provides evidence that these properties significantly impact electric transport in finite-size samples, affecting magnetoresistance.
Area of Science:
- Condensed matter physics
- Materials science
- Solid-state physics
Background:
- Conduction electrons in graphite possess micrometer-scale de Broglie wavelengths and mean free paths.
- The influence of these electron properties on the electrical transport of finite-size graphite samples has been historically overlooked.
- Understanding electron behavior is crucial for advanced electronic applications.
Purpose of the Study:
- To investigate the impact of electron de Broglie wavelength and mean free path on the electrical transport properties of graphite.
- To provide direct experimental evidence for the influence of these lengths on magnetoresistance in finite-size graphite samples.
- To re-evaluate existing models of charge transport in graphite.
Main Methods:
- Experimental measurement of magnetoresistance in graphite samples of varying sizes.
- Analysis of the size dependence of magnetoresistance.
- Comparison of experimental results with theoretical predictions.
Main Results:
- Magnetoresistance was observed to decrease with decreasing sample size, even for samples hundreds of micrometers in size.
- This size-dependent magnetoresistance effect directly correlates with the micrometer de Broglie wavelength and mean free path of conduction electrons.
- The findings challenge previous assumptions about the negligible role of these lengths in finite-size samples.
Conclusions:
- The de Broglie wavelength and mean free path of conduction electrons significantly influence the magnetoresistance of finite-size graphite samples.
- This effect may explain the lack of observed magnetoresistance in small, few-layer graphene samples.
- A revision of experimental and theoretical approaches to graphite's transport properties is warranted.
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...
01:31Magnetic 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...
01:24Potential Due to a Magnetized Object
Magnetic dipoles in magnetic materials are aligned when placed under an external magnetic field. For paramagnets and ferromagnets, dipole alignment occurs in the direction of the magnetic field. However, the dipoles align opposite to the field in the case of diamagnets. This state of magnetic polarization due to the external field is called magnetization. Magnetization is defined as the dipole moment per unit volume. It plays a similar role to polarization in electrostatics.
The vector...
The vector...