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Very large magnetoresistive graphene disk with negative permittivity
Jiahua Zhu1, Suying Wei, Neel Haldolaarachchige
1Integrated Composites Laboratory (ICL), Dan F. Smith Department of Chemical Engineering, Lamar University, Beaumont, Texas 77710, USA.
Nanoscale
|November 10, 2011
Summary
Graphene exhibits a significant 70% magnetoresistance (MR) at room temperature, influenced by its size and surface. Conductivity rises with temperature, and negative permittivity is observed across a broad frequency range.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Nanotechnology
Background:
- Graphene's unique electronic properties make it a candidate for advanced electronic devices.
- Understanding magnetoresistance (MR) in graphene is crucial for its application in sensors and spintronics.
- Room temperature operation is highly desirable for practical electronic applications.
Purpose of the Study:
- To investigate the room temperature magnetoresistance (MR) of graphene.
- To determine the influence of graphene size and surface functionality on MR.
- To characterize the temperature-dependent conductivity and frequency-dependent permittivity of graphene.
Main Methods:
- Fabrication of graphene samples with varying sizes and surface functionalizations.
- Measurement of magnetoresistance (MR) at room temperature.
- Temperature-dependent conductivity measurements.
- Broadband dielectric spectroscopy to determine permittivity.
Main Results:
- A large magnetoresistance (MR) of up to 70% was observed in graphene at room temperature.
- Graphene size and surface functionality significantly affected the MR behavior.
- Conductivity showed a linear increase with temperature.
- A unique negative permittivity was observed over a wide frequency range (10^3 to 10^6 Hz).
Conclusions:
- Graphene demonstrates significant room temperature magnetoresistance (MR) with tunable properties.
- The observed phenomena suggest potential applications in magnetic field sensors and tunable electronic components.
- Further research into surface engineering could optimize graphene for specific device functionalities.
