Chapter 7 - Itinerant ferromagnetism

Abstract

This chapter focuses on the atomic elements. The atomic number of an element is equal to the number of electrons of this element. The reason is that the atomic number is equal to the number of protons in the nuclei. Every proton carries an elementary positive charge that in the neutral state of an atom has to be balanced by a negative elementary charge of electron in the electron shell. The elements are placed in seven rows corresponding to principal quantum number varying from 1 to 7. The superscript on the right denotes the actual number of electrons in the orbit. Orbits with a high-angular momentum have energy comparable with that of higher-principal quantum numbers, but low-angular momentum. When the atoms get close together, the bands formed from the orbits, which are close in energy, start overlapping. The overlapping bands are filled to the same energy, which is called the Fermi energy. It is like a liquid in connected vessels that are filled to the same level. This is why the itinerant electrons are sometimes called the Fermi liquid. The total number of electrons in overlapping bands is the same in the atomic state and in the solid state.