Related Experiment Video
Updated: Aug 15, 2026
12:20
Sputter Growth and Characterization of Metamagnetic B2-ordered FeRh Epilayers
Published on: October 5, 2013
Indication of the ferromagnetic instability in a dilute two-dimensional electron system
A A Shashkin1, S V Kravchenko, V T Dolgopolov
1Physics Department, Northeastern University, Boston, Massachusetts 02115, USA.
Physical Review Letters
|August 11, 2001
Summary
The critical magnetic field for spin polarization in silicon 2D electron systems is linked to electron density deviations near the metal-insulator transition. This suggests a potential ferromagnetic instability in these correlated systems.
Area of Science:
- Condensed matter physics
- Materials science
Background:
- Two-dimensional electron systems (2DES) in silicon exhibit complex electronic behaviors.
- Understanding electron spin polarization is crucial for developing advanced electronic devices.
Purpose of the Study:
- To investigate the relationship between critical magnetic field (B(c)) and electron density.
- To explore the implications of this relationship for ferromagnetic instability in 2DES.
Main Methods:
- Experimental measurement of electron density.
- Analysis of the critical magnetic field required for full spin polarization.
Main Results:
- The critical magnetic field (B(c)) is directly proportional to the deviation of electron density from the zero-field metal-insulator transition point.
- A trend for B(c) to approach zero at a specific electron density was observed.
Conclusions:
- The observed proportionality indicates a strong correlation between electron density and spin polarization.
- The vanishing of B(c) suggests an emerging ferromagnetic instability in the strongly correlated electron system.
Related Concept Videos
02:42Valence Bond Theory
Coordination compounds and complexes exhibit different colors, geometries, and magnetic behavior, depending on the metal atom/ion and ligands from which they are composed. In an attempt to explain the bonding and structure of coordination complexes, Linus Pauling proposed the valence bond theory, or VBT, using the concepts of hybridization and the overlapping of the atomic orbitals. According to VBT, the central metal atom or ion (Lewis acid) hybridizes to provide empty orbitals of suitable...
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.
01:31Ferromagnetism
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...
01:30Paramagnetism
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...
01:28Magnetostatic Boundary Conditions
An electric field suffers a discontinuity at a surface charge. Similarly, a magnetic field is discontinuous at a surface current. The perpendicular component of a magnetic field is continuous across the interface of two magnetic mediums. In contrast, its parallel component, perpendicular to the current, is discontinuous by the amount equal to the product of the vacuum permeability and the surface current. Like the scalar potential in electrostatics, the vector potential is also continuous...
01:18Fermi Level
The Fermi-Dirac function is represented by an S-shaped curve indicating the probability of an energy state being occupied by an electron at a given temperature. The Fermi level is the energy level at which there is a fifty percent chance of finding an electron, and it is positioned between the lower-energy valence band and the higher-energy conduction band.
At absolute zero temperature, electrons fill all energy states up to the Fermi level, leaving upper states empty. As the temperature rises,...
At absolute zero temperature, electrons fill all energy states up to the Fermi level, leaving upper states empty. As the temperature rises,...