Microscopic conditions favoring itinerant ferromagnetism

Wahle, J.; Blümer, N.; Schlipf, J.; Held, Karsten; Vollhardt, D.

doi:10.1103/physrevb.58.12749

Cited by 123 publications

(163 citation statements)

References 59 publications

Supporting

Mentioning

153

Contrasting

Unclassified

Order By: Relevance

“…The results (see e.g. [10,11]) show the existence of ferromagnetism but at much lower temperatures than those coming from the Hartree-Fock approximation. Such results would remove the problem known as a "magnetic paradox", i.e.…”

Section: Introductionmentioning

confidence: 90%

Magnetic ordering of itinerant systems in modified CPA approximation

Górski¹,

Mizia²,

Kucab³

2003

Physica B: Condensed Matter

View full text Add to dashboard Cite

We will analyze the itinerant model for ferromagnetism with both single-site and two-site electron correlations. We will include band degeneration into the model. This will allow us to consider the on-site exchange interactions in the Hamiltonian. The modified Hartree-Fock approximation for the two-site interactions will be used. This approximation will give the relative one spin band broadening with respect to the other, in addition to the shift in position of majority and minority spin bands. Next, we will use the coherent potential approximation technique (CPA) with two self-energies. One will describe the on-site correlation and the second one the inter-site correlation. We will separate from these self-energies, the linear terms arising from Hartree-Fock approximation and the higher order terms. The on-site linear term will contribute only to the effective molecular field. The inter-site linear term will contribute to the effective molecular field and to the inter-site correlation factor. The Green function technique and CPA decoupling will allow for the change in the shape of spin bands, which has been described by the correlation factors and which will decrease the kinetic energy of the system. The gain in kinetic energy due to the on-site and inter-site correlation factors will drive the ferromagnetism and significantly reduce the effective Hartree field necessary to create this ordering.

show abstract

Section: Introductionmentioning

confidence: 90%

Magnetic ordering of itinerant systems in modified CPA approximation

Górski¹,

Mizia²,

Kucab³

2003

Physica B: Condensed Matter

View full text Add to dashboard Cite

show abstract

“…5, where the DMFT results are compared with Hartree-Fock theory [38]. The quantum fluctuations, absent in Hartree-Fock theory, are seen to reduce the stability regime of ferromagnetism drastically.…”

Section: Frustrated Latticesmentioning

confidence: 99%

“…Hirsch [41] argued that this term is the main driving force for metallic ferromagnetism in systems like iron, cobalt, and nickel. Indeed, one can show rigorously that a next-neighbor direct exchange interaction, if only chosen large enough, easily triggers the ferromagnetic instability [42,12,38]. Hence the NN exchange may well be important for systems on the verge of a ferromagnetic instability.…”

Section: Additional Interactionsmentioning

confidence: 99%

See 1 more Smart Citation

Metallic Ferromagnetism — An Electronic Correlation Phenomenon

Vollhardt

Blümer

Held

et al. 2001

Band-Ferromagnetism

Self Cite

View full text Add to dashboard Cite

Abstract. New insights into the microscopic origin of itinerant ferromagnetism were recently gained from investigations of electronic lattice models within dynamical meanfield theory (DMFT). In particular, it is now established that even in the one-band Hubbard model metallic ferromagnetism is stable at intermediate values of the interaction U and density n on regular, frustrated lattices. Furthermore, band degeneracy along with Hund's rule couplings is very effective in stabilizing metallic ferromagnetism in a broad range of electron fillings. DMFT also permits one to investigate more complicated correlation models, e.g., the ferromagnetic Kondo lattice model with Coulomb interaction, describing electrons in manganites with perovskite structure. Here we review recent results obtained with DMFT which help to clarify the origin of band-ferromagnetism as a correlation phenomenon.

show abstract

“…To illustrate the results we will use later on the asymmetrical function of Ref. [17] for the unperturbed DOS [see Eq. (35)].…”

Section: (B)-2(d)mentioning

confidence: 99%

Magnetic ordering of itinerant systems: the role of kinetic interactions

Górski

Mizia

2004

Physica B: Condensed Matter

View full text Add to dashboard Cite

The possibility of ferromagnetic ordering is revisited in the band model. The coherent potential approximation decoupling has been used for the strong on-site Coulomb interaction. The driving forces towards the ferromagnetism are the on-site and inter-site molecular fields coming from different Coulomb interactions. Another driving force is the lowering of the kinetic energy with growing magnetic moment coming from the dependence of the hopping integrals on occupation of the neighboring sites involved in hopping. This effect is described by the hopping interaction, ∆t , and by what we call the exchange-hopping interaction, tex. The exchange-hopping interaction, which is the difference in hopping integrals for different occupation of neighboring lattice sites, acts in analogous way to the Hund's magnetic exchange interaction. The results are calculated for semi-elliptic density of states (DOS) and for the distorted semi-elliptic DOS with the maximum around the Fermi energy. They show a natural tendency towards the magnetic ordering at the end of the 3d row for the DOS with maximum density around the Fermi energy, when the hopping integrals grow with the occupation of the neighboring lattice sites.

show abstract

Microscopic conditions favoring itinerant ferromagnetism

Cited by 123 publications

References 59 publications

Magnetic ordering of itinerant systems in modified CPA approximation

Magnetic ordering of itinerant systems in modified CPA approximation

Metallic Ferromagnetism — An Electronic Correlation Phenomenon

Magnetic ordering of itinerant systems: the role of kinetic interactions

Contact Info

Product

Resources

About