Sumários

T16 - Tunnel effect

22 Abril 2024, 17:30 • Maria Margarida Cruz

Transference through a barrier. Tunnel effect. Tunnel effect barrier seen as ballistic conductance with small transmission. Limit for barrier resistance to exist tunnel effect. Orthodox condition for an electron to be transfer across the barrier.

 



T15 - Aharonov-Bohm effect

22 Abril 2024, 15:00 • Maria Margarida Cruz

Electrons with trajectories enclosing magnetic flux. Phase variation. Aharonov-Bohm effect. 
Diffusive coherent transport. Weak localization effect.
Explanation of the destruction of the weak localization effect by the magnetic field. Weak localization and Aharonov-Bohm effect h/2e.

T14 - Quantum effects in electrical transport

15 Abril 2024, 17:30 • Maria Margarida Cruz

Coherent transport through a one-dimensional conductor with two scattering centers. Scattering matrix (S) and transfer matrix (T). Relationship between both matrices. Difference between the electrical resistances obtained with coherent transport and with incoherent transport.

T13 - Quantum Hall Effect

15 Abril 2024, 15:00 • Maria Margarida Cruz

Multiplicity of Landau levels. Magnetic length. Relationship with magnetic flux.

Electrons in a parabolic confinement potential and subject to an intense magnetic field.
Charge transport by border states. Localization of Landau states by impurities. Synthesis of the main aspects involved in Quantum Hall Effect.
Qualitative discussion of the fractional quantum Hall effect.


T12 - Landau levels

8 Abril 2024, 17:30 • Maria Margarida Cruz

Integer Quantum Hall Effect.
Two-dimensional gas of electrons subject to a magnetic field. Landau levels. Multiplicity and filling factor.
The chemical potential of two-dimensional electron gas with applied magnetic field.