Cerium influence on the spin reorientation in Er2−Ce Fe14B evidenced by Mössbauer and DSC techniques (original) (raw)
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Spin reorientation phenomena in Er2-xRxFe14B (R = Gd, Th) - Mössbauer and calorymetric study
Nukleonika
The Er 2−x Gd x Fe 14 B (x = 0.5, 1.0, 1.5) and Er 2−x Th x Fe 14 B (x = 0.0, 0.5, 1.0, 1.5, 2.0) polycrystalline compounds have been investigated with 57 Fe Mössbauer spectroscopy and differential scanning calorimetry (DSC). A comparison of results related to spin reorientation phenomena obtained for Gd-and Th-substituted compounds is presented in this paper. Spin reorientation phenomena (changes from planar to axial spin arrangements) have been studied extensively by a narrow step temperature scanning in the neighbourhood of the spin reorientation temperature, T SR. From the analysis of Mössbauer spectra, it was deduced that in the region of transition each subspectrum was split into two Zeeman sextets, which were characterised by different hyperfine magnetic fields and quadrupole splittings. A consistent way of fitting the spectra in the wide range of temperatures was proposed. The composition and temperature dependencies of hyperfine interaction parameters and subspectra contributions were derived from fits and the transition temperatures were determined for all the compounds studied. DSC studies proved that the spin reorientations were accompanied by thermal effects for all compositions of the Gd-and for x = 0.5 of the Th-series. Transformation enthalpy and T SR were determined from these studies and the two-stage character of transition was confirmed. Magnetic spin arrangement diagrams for R = Th and Gd series were constructed and compared using combined data obtained with both methods.
Nukleonika
Two isostructural series of polycrystalline compounds: Er 2−x Y x Fe 14 B and Er 2−x Ce x Fe 14 B have been studied by 57 Fe Mössbauer spectroscopy in the temperature range 80−370 K. The spin reorientation phenomenon (a transition from basal plane to axial easy magnetisation direction) has been studied extensively by a narrow step temperature scanning in the vicinity of the transition. Using the procedure of subtracting the Mössbauer spectra taken for the same compound at different temperatures, it was possible to follow the influence of transition on the shape of spectra. From this procedure it was concluded that in the region of transition each subspectrum splits into two Zeeman sextets, which are characterised by different hyperfine magnetic fields and quadrupole splittings. The consistent way of describing the Mössbauer spectra was proposed. The spin reorientation temperatures have been established for all compositions and compared with the values obtained from theoretical calculations of spin orientation angle based on phenomenological model. The spin arrangement diagrams have been constructed.
Spin reorientation studies in Er 2− x Gd x Fe 14B
Solid State Ionics, 2005
57Fe Mössbauer spectroscopy, differential scanning calorimetry (DSC), magnetic measurements and X-ray diffraction have been used to study the polycrystalline Er2−xGdxFe14B (x=0.0, 0.5, 1.0, 1.5) compounds. Special emphasis was put on the spin reorientation phenomena (change of spin orientation from planar to axial arrangement) occurring in this series. The spin reorientation in each compound has been investigated mainly by narrow step
Mössbauer effect evidence of spin reorientation in (Er 1 − x Ce x ) 2Fe 14B intermetallic compounds
Journal of Alloys and Compounds, 1996
in (Er,_,Ce,),Fe,,B system, originating from competition between the magnetic anisotropies of the erbium and iron sublattices, was observed by the 57Fe MGssbauer spectroscopy below room temperature. The spin transition temperature is lowered by non-magnetic dilution within the rare earth crystal sublattice, caused by substitution of cerium for erbium. There is evidence that the process proceeds not at a discrete temperature but in a wide temperature range. The discrete values of the "Fe hypetie interaction parameters, derived from MGssbauer absorption spectra, are consistent with localized interactions of iron atoms with their nearest neighbours. It was found that substitution of cerium for erbium slightly reduces hyperflne magnetic fields at iron sites and it only has a minute influence on the values of the isomer shifts and quadrupole interactions. Keywords: Spin reorientation; Ternary rare earth compounds; R-Fe-B compounds; MGssbauer effect 09258388/96/$15.00 0 1996 Elsevier Science S.A. All rights reserved SSDlO925-8388(95)01945-6
Mössbauer studies of spin reorientations in Er2-xGdxFe14B
Nukleonika
The Er 2−x Gd x Fe 14 B (x = 0.5, 1.0, 1.5) polycrystalline compounds have been investigated with 57 Fe Mössbauer spectroscopy in the 80−330 K temperature range. The spin reorientation phenomena (changes from planar to axial spin arrangements) have been studied extensively by a narrow step temperature scanning in the neighbourhood of the spin reorientation temperature. From the analysis of the spectra it was deduced that in the region of transition each subspectrum was split into two Zeeman sextets, which were characterized by different hyperfine magnetic fields and quadrupole splittings. A consistent way of describing the Mössbauer spectra in the wide range of temperatures was proposed. The composition and temperature dependencies of hyperfine interaction parameters and subspectra contributions were derived from experimental spectra. The transition temperatures were determined for all the compounds studied.
Mössbauer Investigation of Spin Arrangements in Er2-xCexFe14B
Acta Physica Polonica A, 2008
It was theoretically postulated earlier that in compounds Er2−xCexFe14B it may be possible to observe not only axial and planar spin arrangements but also a conical one. In order to experimentally verify this hypothesis, 57 Fe Mössbauer spectroscopy analysis was used to study the polycrystalline compounds Er 2−x Ce x Fe 14 B in the postulated composition region (x = 1.0, 1.1, 1.2, 1.3) in the wide range of temperatures. The obtained experimental data do not clearly support the suggestion of conical arrangement occurrence in the postulated compositions. They indicate that such phenomenon may be shifted towards higher Ce content.
Mössbauer effect evidence of spin reorientation in (Er1 − Ce )2Fe14B intermetallic compounds
Journal of Alloys and Compounds, 1996
Spin reorientation in (Er,_,Ce,),Fe,,B system, originating from competition between the magnetic anisotropies of the erbium and iron sublattices, was observed by the 57Fe MGssbauer spectroscopy below room temperature. The spin transition temperature is lowered by non-magnetic dilution within the rare earth crystal sublattice, caused by substitution of cerium for erbium. There is evidence that the process proceeds not at a discrete temperature but in a wide temperature range. The discrete values of the "Fe hypetie interaction parameters, derived from MGssbauer absorption spectra, are consistent with localized interactions of iron atoms with their nearest neighbours. It was found that substitution of cerium for erbium slightly reduces hyperflne magnetic fields at iron sites and it only has a minute influence on the values of the isomer shifts and quadrupole interactions.