Electrical conduction and magnetic properties of matter
Let’s describe processes of current conduction in metals. Electron, which carries current, is marked with blue. Thermal motion combines chaotic movement of electrons from one atom to another with oscillating of atoms.
Succession is like this. Atom rotates together with conduction electron, than conduction electron moves from one atom to another. Velocity of movement is rather slow. Electric field is transferred by rotation of the atoms (velocity of transferring is very high).
There is no necessity to invent any forbidden energy gap and explain why velocity of electrons’ drift is less than their thermal motion.
Oscillations of the atoms and their thermal rotations increase when temperature of the metal rises. Both types of motion (purposeful movement and movement from one atom to another) become complicated. So resistance increases too.
Atoms’ oscillations and rotations, which result from influence of temperature, increase when temperature falls. It becomes easy for conduction electron to occupy vacant positions. When temperature becomes very low vacant places form so called tunnel, which becomes straighter with further cooling. You understand that it is description of superconductivity. Let’s compare it with modern theory of superconductivity. It is based on the formation of Cooper electron pairs. These electrons pull along each other instead of repulsing. This behavior isn’t clear. Meissner effect, when magnetic field is pushed out of superconductor, is explained by the instrumentality of straightening of the way of every conduction electron. It results in possibility to form space conformations of electrons in atoms. This formation lets to ferromagnetic effects (look below).
There are only four vacancies in electron shell of semiconductor.
They located tetrahedrally.
Vacancies in electron shell are shown with white color (one of the vacant cells is on the other side, so we can’t see it on the picture). Vacant place, occupied by electron, which carries current, is shown with red color.
In case of metal there is no necessity for electron to rotate atom, but in case of semiconductor rotation is the compulsory requirement. But further way can occur impossible, because empty cell in next atom can be oriented in another direction
Increasing of the temperature hastens the process of atom rotation and increases probability of appearing a vacant cell opposite the conduction electron (electron is shown with the red color on the picture).
Identical dependence of thermal conductivity and electroconductivity, expressed in Wiedemann-Franz law, becomes clear. Liquid helium is the best corroboration of such conception of thermal and electro conductivity. When temperature is below 2,19K, sum of two electron areas looks like sphere. So atoms can rotate very easily even under influence of conduction or thermal electron.
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