Field induced local magnetic moments in gamma-fcc Fe-Ni anti-Invar alloys
2004 (English)In: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, Vol. 280, 243-250 p.Article in journal (Refereed) Published
Mössbauer spectroscopy in longitudinal external fields (up to 7 T) and SQUID magnetometry (up to 5 T)measurements have been carried out on mechanically alloyed (MA) g (FCC) Fe100xNix (x ¼ 21; 24, and 27 at%) alloysat room temperature. The zero-field M.ossbauer spectra of these alloys show only singlets. The high field M.ossbauerresults indicate that large amounts of the material is in the paramagnetic state, giving rise to two spectral componentswith their effective fields almost linearly depend on the external field, but with slopes that are smaller than unity. The infieldM.ossbauer spectra of the x ¼ 27 at% alloy show an additional component with a hyperfine field of E21 T, whichis attributed to Ni-rich (>30 at% Ni) clusters (domains) of ferromagnetically ordered HM phase that behavessuperparamagnetically at room temperature and shows a non-linear character in the magnetization (M–H) curves atlow fields. This HM phase is also present in the x ¼ 21 and 24 at% samples but with smaller amounts. The resultssuggest induced hyperfine fields and hence induced moments in the paramagnetic components, which increases withincreasing Ni contents. Taenite-enriched samples from the metal particles of two stony meteorites, Al Kidirate (H6)and New Halfa (L4), are also studied by high field M.ossbauer spectroscopy and the results are compared to that ofMA samples.
Place, publisher, year, edition, pages
2004. Vol. 280, 243-250 p.
Mössbauer spectroscopy; External field; Magnetization; Fe–Ni alloys; Antitaenite
IdentifiersURN: urn:nbn:se:uu:diva-91279OAI: oai:DiVA.org:uu-91279DiVA: diva2:163960