Competition of Two Terms in Exchange Hamiltonian for magnetic substances

Abstract

The unjustifiable or wrong in the previous magnetism theories has been indicated in this paper. For a N electrons system with Heisenberg exchange integral, the correct exchange Hamilton should be of two terms, not only one as in the previous magnetism theories. The role of the minor term in the exchange Hamilton was considered. Based on the principle of superposition of state, the eigenstate of the system with Heisenberg exchange integral, the sum of a positive term and a negative term, and the energy (relative to exchange interaction) eigenvalue were attained. When the positive term is equal to the absolute value of the negative term, the system is in the spin glass state, the probabilities of parallel and antiparallel arrange for every pair of spins of electron of nearest neighbours in the system are equal. When the positive term is not equal to the absolute value of the negative term,the probabilities are not equal, and there coexist the ferromagnetic states and spin glass or antiferromagnetic state and spin glass,when ferromagnetic states and spin glass or antiferromagnetic state and spin glass coexist, the energy of the system is lower than that when only ferromagnetic states or antiferromagnetic state exists as in previous theory. Weiss ferromagnetic state or Neel anti ferromagnetic state is just a special state as the positive term is equal to zero or negative term is equal to zero.