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 Mössbauer 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, ηF=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 Mössbauer spectral analysis and reveals a magnetic triple point at x=∼0.35 and ∼210 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.
R. P. Hermann et al., "Mössbauer Spectral Study of the Magnetocaloric FeMnP₁₋ₓAsₓ Compounds," Physical Review B, American Physical Society (APS), Jan 2004.
The definitive version is available at http://dx.doi.org/10.1103/PhysRevB.70.214425
Keywords and Phrases
Magnetic Phase Transitions
Library of Congress Subject Headings
Article - Journal
© 2004 American Physical Society (APS), All rights reserved.