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Magnetism Stoner band theory

The Stoner model, which we discuss in its simplest form, describes the formation of a net magnetic moment for itinerant electrons in a narrow band by adding to the basic Hamiltonian (11) of band theory a perturbing term accounting for total energy increase in case the itinerant electrons spins are not polarized (as in an atom for states not maximizing the spin). [Pg.35]

Many ferromagnets are metals or metallic alloys with delocalized bands and require specialized models that explain the spontaneous magnetization below Tc or the paramagnetic susceptibility for T > Tc. The Stoner-Wohlfarth model,6 for example, explains these observed magnetic parameters of d metals as by a formation of excess spin density as a function of energy reduction due to electron spin correlation and dependent on the density of states at the Fermi level. However, a unified model that combines explanations for both electron spin correlations and electron transport properties as predicted by band theory is still lacking today. [Pg.76]

In the past the effort to improve the understanding of finite temperature magnetic properties has mainly concentrated on itinerant ferromagnetic materials like Fe, Co, and Ni. The theoretical starting point was the one-electron finite temperature band theory which is known under the name Stoner-theory [108, 109]. Within... [Pg.114]

In the Stoner theory for magnetism, it is shown that magnetic ordering is possible in a band scheme, when spin-polarization is energetically favorable the full discussion (see Chap. A) for the simpler case of ferromagnetism leads to a simple criterion known as the Stoner criterion ... [Pg.129]

Like in molecular quantum chemistry, the localized-delocalized antagonism is omnipresent in the theoretical literature on itinerant magnetism. On the one hand, the Hubbard model [292] and related theories for strongly correlated systems have been employed to study rare-earth and also transition metals. Since the latter do not have flat bands, extensions to the Hubbard theory are required [293-295] also, to make the model Hamiltonians (almost) exactly solvable, simplifications are introduced. On the other hand, density-functional theory is able to extract Stoner s parameters [296,297] for a self-consistent description of itinerant magnetism [298]. As has been illustrated before, the theoretical limits of the LDA became apparent from Fe phase stability problems (see Section 2.12.1) and were solved by using gradient corrections. The present status of DFT in the treatment of cooperative magnetism has also been reviewed [299]. [Pg.193]

A more complex magnetic behaviour is expected for RI compounds in which the second component is a 3d transition metal such as Mn, Fe, or Co. The magnetic behaviour of the transition metal component is now based on the magnetic polarization of the electronic d-bands. Consequently, in this section we summarize the theory of itinerant or band magnetism and its application to transport properties. We begin with the Stoner-Wohlfarth model and include a summary of recent works. [Pg.175]


See other pages where Magnetism Stoner band theory is mentioned: [Pg.214]    [Pg.227]    [Pg.115]    [Pg.185]    [Pg.24]    [Pg.132]    [Pg.176]    [Pg.182]    [Pg.254]    [Pg.185]    [Pg.48]    [Pg.227]    [Pg.280]    [Pg.221]    [Pg.223]    [Pg.317]    [Pg.223]    [Pg.133]   
See also in sourсe #XX -- [ Pg.227 ]




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