Related Experiment Video
Updated: Jul 10, 2026
11:42
Fabrication of Gate-tunable Graphene Devices for Scanning Tunneling Microscopy Studies with Coulomb Impurities
Published on: July 24, 2015
Magnetism in graphene nanoislands
J Fernández-Rossier1, J J Palacios
1Departamento de Física Aplicada, Universidad de Alicante, San Vicente del Raspeig, Alicante E-03690, Spain.
Physical Review Letters
|November 13, 2007
Summary
We investigated magnetic properties of nanometer-sized graphene shapes. Graphene triangles exhibit finite spin, while hexagons develop magnetic moments above 1.5 nm.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Nanotechnology
Background:
- Graphene nanostructures exhibit unique electronic and magnetic properties.
- The interplay between shape, sublattice imbalance, and magnetism in graphene is not fully understood.
Purpose of the Study:
- To investigate the magnetic properties of triangular and hexagonal graphene nanostructures with zigzag edges.
- To elucidate the relationship between island shape, sublattice imbalance, zero-energy states, and magnetic moments.
Main Methods:
- Utilized the one-orbital Hubbard model within a mean-field approximation.
- Performed density functional calculations to analyze electronic interactions and magnetic properties.
Main Results:
- Both theoretical models confirm ground state total spin values consistent with Lieb's theorem.
- Triangular graphene nanostructures display a finite total spin (S) irrespective of size.
- Hexagonal graphene nanostructures show S=0 and develop local magnetic moments for sizes exceeding approximately 1.5 nm.
Conclusions:
- Graphene nanostructure shape critically influences magnetic properties.
- Sublattice imbalance and zero-energy states are intrinsically linked to magnetic moment formation.
- Size-dependent magnetic behavior is observed in hexagonal graphene, distinguishing it from triangular counterparts.
Related Concept Videos
01:28Magnetic Fields
A moving charge or a current creates a magnetic field in the surrounding space, in addition to its electric field. The magnetic field exerts a force on any other moving charge or current that is present in the field. Like an electric field, the magnetic field is also a vector field. At any position, the direction of the magnetic field is defined as the direction in which the north pole of a compass needle points.
A magnetic field is defined by the force that a charged particle experiences...
A magnetic field is defined by the force that a charged particle experiences...
01:26Diamagnetism
Materials consisting of paired electrons have zero net magnetic moments. However, when these materials are placed under an external magnetic field, the moments opposite to the field are induced. Such materials are called diamagnets. Diamagnetism is the response of the diamagnets when placed in an external magnetic field.
Diamagnetism was discovered by Anton Brugmans in 1778 when he observed that bismuth gets repelled by magnetic fields, thus theorizing that diamagnets get repelled by magnets.
Diamagnetism was discovered by Anton Brugmans in 1778 when he observed that bismuth gets repelled by magnetic fields, thus theorizing that diamagnets get repelled by magnets.
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...
01:30Magnetism
Magnets are commonly found in everyday objects, such as toys, hangers, elevators, doorbells, and computer devices. Experimentation on these magnets shows that all magnets have two poles: one is labeled north (N) and the other south (S). Magnetic poles repel if they are alike and attract if unlike. Moreover, both poles of a magnet attract unmagnetized pieces of iron.
An individual magnetic pole cannot be isolated. No matter how small, every piece of a magnet contains a north pole and a south...
An individual magnetic pole cannot be isolated. No matter how small, every piece of a magnet contains a north pole and a south...
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...
01:15Magnetic Vector Potential
In electrostatics, the electric field can be written as the negative gradient of the potential. In magnetostatics, the zero divergence of the magnetic field ensures that the magnetic field can be expressed as the curl of a vector potential. This potential is known as the magnetic vector potential.
Consider an ideal solenoid with n turns per unit length and radius R. If I is the current through the solenoid, the magnetic field inside the solenoid is expressed as the product of vacuum...
Consider an ideal solenoid with n turns per unit length and radius R. If I is the current through the solenoid, the magnetic field inside the solenoid is expressed as the product of vacuum...