The effective Curie-Weiss constant of ferromagnetic metals and alloys

HAL Id: jpa-00236671

https://hal.archives-ouvertes.fr/jpa-00236671

Submitted on 1 Jan 1962

HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci- entific research documents, whether they are pub- lished or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers.

L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

The effective Curie-Weiss constant of ferromagnetic metals and alloys

E.P. Wohlfarth, P. Rhodes

To cite this version:

E.P. Wohlfarth, P. Rhodes. The effective Curie-Weiss constant of ferromagnetic metals and alloys. J.

Phys. Radium, 1962, 23 (10), pp.729-729. �10.1051/jphysrad:019620023010072901�. �jpa-00236671�

729

in iron above the Curie point ^is drawn, ^{this band}

would fluctuate through ^the lattice, ^as is repre- sented in figure ^3.

From the foregoing it follows that A and some

of the other constants mentioned above are not

strongly dependent ^on temperature, which agrees with ,the experimental ^{results. This} picture ^is

therefore the justification ^{of the} applicability ^of

equation (1), ^not olily ^{at 0} OK, but al all tempe-

ratures. The author wishes to express his grati-

tude to Prof. Dr. G. W. Rathenau, for many helpful

discussions. This work is part ^{of the research}

program of the " Stichting ^voor Fundamenteel Onderzoek der Materie " and was made possible by ^financial support from the " Nederlandse Orge- -

nisatie voor Zuiver Wetenschappelijk Onderzoek ".

.

REFERENCES

[1] ^GERSDORF (R.), ^STOELINGA (J. ^H. M.) and RATHENAU

(G. W.), International Conference on Magnetism ^and Crystallography, Kyoto, Japan, 1961.

GERSDORF (R.), Thesis, Amsterdam, ^1961.

[2] ^BOZORTH (R. M.), Ferromagnetism, ^van Nostrand Co.

Princeton N. J., 1956, p. 431.

[3] ^KITTEL (C.), Introduction to Solid State Physics,

J. Wiley & Sons, ^New York, 1956, pp. 405-407.

[4] ^WEISS (P. R.), Phys. Rev., 1948, 74, 1493.

[5] ^KOUVEL (J. S.) ^{and WILSON} (R. H.), ^J. Appl. Phys., 1961, 32, ^{276 S.}

[6] ^PATRICK (L.), Phys. Rev., 1954, 93, 384.

[7] ^BELDING (E. F.), ^Phil. Mag., 1959, 4, 1145.

[8] ^STONER (E. C.), ^Proc. Roy. Soc., 1938, ^A 165, 372.

THE EFFECTIVE CURIE-WEISS CONSTANT OF FERROMAGNETIC METALS AND ALLOYS

By E. P. WOHLFARTH

Department ^of Mathematics, Imperial College, London, England.

and P. RHODES

Department ^of Physics, ^The University, Leeds, England.

Résumé. 2014 Les valeurs expérimentales de la constante de Curie-Weiss et l’aimantation de saturation de beaucoup de substances ferromagnétiques ^sont utilisées pour le calcul des valeurs

correspondantes des nombres de porteurs ^de moments, qc et qs. Un graphique ^du rapport qc/qs ^en fonction, ^{de la} température ^{de Curie montre deux} branches. Pour l’une d’elles, qc/qs ^~ 1, et pour l’autre qc/qs > 1. La premiere correspond ^aux substances (par ^{ex. Gd et Mn} Sb) ^{conformes à un}

modèle purement localise de ferromagnétisme, la seconde à celles (comme ^les alliages ^{dilués de} palladium ^{et de fer ou de} cobalt, ^{et les} composés ^{de Mathias} Sc3In ^{et Zr} Zn2) ^{conformes au modèle} intermédiaire, qui ^se réduit, ^dans la théorie présentée, ^{au modèle} électronique collectif. Les calculs d’une grandeur étroitement liée au rapport qc/qs ^sont donnés pour différentes formes de la courbe de densité d’états, ^{dont une avec une} pointe aiguë. ^L’accord quantitatif ^avec la seconde branche est bon.

Abstract.

Experimental data for the Curie-Weiss constant and the saturation magnetization

of a wide variety ^of ferromagnetic substances are used to calculate respective values for the number of magnetics carriers, qc and _qs. A plot ^{of the ratio} qc/qs ^as dependent ^{on the Curie} temperature

reveals two branches. For one of these qc/qs

^{1 and for the other} qc/qs > 1. The first branch

corresponds ^to substances (e.g. ^{Gd and Mn} Sb) obeying ^a purely localized model of ferromagnetism,

and the second to substances (such ^{as dilute} palladium alloys ^{with iron and} cobalt, and the Matthias

compounds Sc3In ^{and Zr} Zn2) obeying the " intermediate model ", which reduces in the present

context to the collective electron model. Calculations of a quantity ^closely related to the ratio qc/qs ^are reported ^for different forms of the density ^{of states} curve, including ^{one with a} sharp peak. ^The qualitative agreement with the second branch is good.

LE JOURNAL DE PHYSIQUE ^{ET LE RADIUM TOME} 23, ^OCTOBRE 1962,

(*) ^{The full text of} this paper will be published ^elsewhere.

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphysrad:019620023010072901