[en] The magnetic phase transitions in the FeMnP1-xAsx compounds with x= 0.25, 0.35, 0.45, 0.50, and 0.55, have been studied by iron-57 Mossbauer spectroscopy. The ferromagnetic and antiferromagnetic spectra have been analyzed with a model that takes into account the random distribution of the P and As near-neighbor anions of a given iron site. This distribution is a binomial distribution of the contributions to the spectra of each iron with n As near neighbors. A magnetostriction model has been used to characterize the temperature induced paramagnetic to ferromagnetic first-order phase transition and order parameters, eta(F)=2.6, 2.3, 2.0, 1.57, and 1.43 have been obtained for x=0.25, 0.35, 0.45, 0.50, and 0.55, respectively. A detailed phase diagram has been derived from the Mossbauer spectral analysis and reveals a magnetic triple point at x=similar to0.35 and similar to210 K. A model that takes into account the random binomial P and As distribution and the contribution from the iron and manganese magnetic sublattices yields excellent fits of the spectral components assigned to the ferromagnetic and incommensurate antiferromagnetic components for the x=0.25 and 0.35 compounds at all temperatures.
Disciplines :
Physics
Author, co-author :
Hermann, Raphaël ; Université de Liège - ULiège > Département de physique > Département de physique
Tegus, O.
Bruck, E.
Buschow, K. H. J.
de Boer, F. R.
Long, G. J.
Grandjean, Fernande ; Université de Liège - ULiège > Département de physique > Département de physique
Language :
English
Title :
Mossbauer spectral study of the magnetocaloric FeMnP1-xAsx compounds
Publication date :
2004
Journal title :
Physical Review. B, Condensed Matter and Materials Physics
ISSN :
1098-0121
eISSN :
1550-235X
Publisher :
American Physical Soc, College Pk, United States - Maryland
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