Hall effect and quantum effect Hall

1998/12/01 Elhuyar Zientzia Iturria: Elhuyar aldizkaria

• Fisika
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If a thin metallic foil is placed inside a magnetic field forming the surface of the foil a right angle with respect to the direction of the field, and an electric current is passed in the direction of the longitudinal axis of the plate, an electric field that forms an angle of 90º with respect to the magnetic field and the electric current, that is, a difference of potential.

The electric field is proportional to the current density and magnetic induction. This phenomenon is known as Hall effect, Edwin H. It was discovered by Hall in 1879. This phenomenon is due to the appearance of a force that sideways the electrons by moving the particles with electric charge (in this case the electrons) inside the magnetic field.

The Hall effect can be used to measure the density of the load carriers (negative electrons or positive voids) and currently gauges based on the Hall effect are used in laboratories around the world.

Using low temperatures (-272 °C) and large magnetic fields (of the order of 30 teslas) the Hall effect has been studied in semiconductor materials (that is, with very thin layers of material), where it has been observed that the nature of the Hall effect changes. In 1980 Klaus von Klitzing discovered that the Hall conductance does not depend on the characteristics of the material, but is quantified, that is, the capacity of the electrons is quantified to transport the electric charge and varies not linearly depending on the temperature, but to jumps.

In addition, the magnitude of these jumps does not depend on the characteristics of the material, but the values of the Hall conductance are obtained by multiplying by an entire number the combination of certain basic physical constants (electron charge and Planck constant). This discovery is called Hall quantum effect (temperature at which the atomic resistance disappears and the material becomes superconductor). This effect can be understood using the laws of quantum physics.