CFU
6
Length
14 Weeks
Semester DD
Second
Basic concepts to the transport theory in 3 dimensional solids: electrical conducibilità, Ohms law, mean free path, free electron gas, Bloch theorem, energy bands, effective mass, Boltzmann approximation, relaxation time, electrical current and conducibility. Quantum confined systems: 2 dimensional electron gas, quantum wells, ethero structures, multilayers, nanowires, nanodots.
Effects of the magnetic field: Landau levels, Subnikov-Dehaas effect, quantum Hall effect. Tunnel effect: Landauer formula, negative resistance and tunnel diode. Quantum conductance, ballistic effect, weak localization, Coulomb blockade. Transport mechanism in granular systems, carbon nanotubes, graphene, topological insulators. Low dimensional superconductivity, anisotropy, interface superconductivity, proximity effect. Experimental methods: Deposition methods: sputtering, MBE. Resistivity measurements methods: 2 and 4 leads measurements; Van der Paw method. Metallic thin film deposition; resistivity measurement of a metallic thin film. Mean free path measurement. Calculation of the Debye temperature through the Bloch-Gruneisen model
LEARNING OUTCOMES:
At the end of the course the student must show a knowledge of physics phenomena related to low-dimensional systems with particular attention to electric transport phenomena. It must be aware of the meaning of low dimensionality, of the difference in the properties of electric transport with traditional systems, of the peculiar phenomena of low dimensionality. They must also have a good knowledge of the state of the art of experimental phenomena and materials in which low-dimensional phenomena emerge
KNOWLEDGE AND UNDERSTANDING:
It is expected that the student will be able to perform simple exercises in quantum mechanics in which the rules of low dimensionality are applicable. That it is capable of representing a low-dimensional phenomenon and the corresponding phenomenon in three-dimensional physics.
APPLYING KNOWLEDGE AND UNDERSTANDING:
Students must be able to identify the essential elements of a physical problem and know how to model them, making the necessary approximations. In particular it requires the ability to analyze some experiments in the literature and to give an explanation based on the theories studied.
MAKING JUDGEMENTS:
The student must be able to understand whether a given physical phenomenon can be interpreted through classical quantum theory or needs different rules. He must be able to judge whether a physical system is of the low-dimensional type and how its nature can emerge by identifying the possible conditions in which to perform an experiment.
COMMUNICATION SKILLS:
The student must be able to understand whether a given physical phenomenon can be interpreted through classical quantum theory or needs different rules. He must be able to judge whether a physical system is of the low-dimensional type and how its nature can emerge by identifying the possible conditions in which to perform an experiment.
LEARNING SKILLS:
At the end of the course the student will be asked to illustrate some low-dimensional phenomena in order to demonstrate their degree of understanding.