Influence of impurities on the band ferromagnetism

Ciobanu, G.; Fazakas, A. B.

doi:10.1007/bf01394621

Cited by 3 publications

(2 citation statements)

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“…This looks very much like the standard result [13], but shows the important role played by the Hubbard interaction. This is easy t o see even if we only derive (from (4.8)) the Bloch criterion for the pure specimen,…”

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confidence: 82%

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Influence of Non‐Magnetic Impurities on the Ferromagnetic Phase Transition and Its Critical Properties

Fazakas¹,

Corcoţtoi²,

Ciobanu³

1988

Physica Status Solidi (b)

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The free energy functional is derived for an electron gas interacting via insite Hubbard and intersite Heisenberg terms, scattered by some dilute, interstitial, non-magnetic impurities. The equation for the Curie temperature is deduced and discussed in various approximations. The existence is shown of a critical concentration of impurities destroing the ferromagnetism. The dirty specimen has the same critical exponents as the pure one, but the width of the critical region is modified.On deduit la fonctionelle de 1'8nergie libre d'un systeme d'electrons en interaction dbcrite par un hamiltonien aux termes de type Hubbard pour le mbme site du rbseau, Heisenberg pour sites differentes, complbtb par un potential decrivant des impuretes non-magn6tiques interstitielles. La deduction de ]'equation pour la temperature critique est suivie d'une discussion des diffhentes approximations. On prouve l'existence d'une concentration critique d'impureths detruisant le ferromagnetisme. Les exposants critiques sont les m6mes que pour le systkme pur, mais 1'6paisseur de la region critique est modifiee.

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Section: )supporting

confidence: 82%

“…This means a decrease of the Curie temperature due to impurities. I n fact (see also [13]) there exists a oritical relaxation time (i.e. a critical impurity concentration) which destroys ferromagnetism.…”

Section: )mentioning

confidence: 99%

Influence of Non‐Magnetic Impurities on the Ferromagnetic Phase Transition and Its Critical Properties

Fazakas¹,

Corcoţtoi²,

Ciobanu³

1988

Physica Status Solidi (b)

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Magnetic and Excitonic Instabilities in a Two‐Band Model

Teleman

Ciobanu

Fazakas

1972

Physica Status Solidi (b)

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A two-band model with short range interactions between electrons is studied in order to find magnetic and excitonic instabilities. Using the vertex part equation method, some general conditions for the appearance of instabilities leading to phase transitions are derived.Due to the existence of different coupling constants and the possibility of various band shapes, many cases appear and are discussed.On a ktudi6 un modhle a deux bandes d'hnergie d'un gaz d'616ctron interagissant par des forces A court rayon d'action. E n utilisant les dquations pour l'opdrateur d'interaction on a obtenu les conditions gdnhrales ndcessaires pour l'apparition des insta bilit6s magn6-tiques e t excitoniques qui conduisent aux transformations de phase. On a ensuite discub5 plusieurs cas particuliers correspondant i divers types de constantes de couplage et de structures de bandes.

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