A Mössbauer spectral study of the Nd6Fe13X compounds where X is Si, Cu, Ag, and Au

Abstract

The Mössbauer spectra of Nd 6 Fe 13 X, where X is Si, Cu, Ag, and Au, have been measured between 85 and 435 K. An analysis of the spectra of Nd 6 Fe 13 X, where X is Cu, Ag, and Au in terms of five sextets, indicates that the iron moments lie in the basal plane of the unit cell. The assignment of the five sextets to the five magnetically inequivalent sites in the structure is based on a correlation between the isomer shift and the Wigner-Seitz cell volume for all iron sites, between the isomer shift and the hyperfine field for each site, and the relationship between the hyperfine field at a given iron site and its number of iron near-neighbors. An analysis of the spectra of Nd 6 Fe 13 Si reveals that a high temperature magnetic phase, with its moments parallel to the c axis, coexists between 295 and 85 K with a low temperature magnetic phase, with its moments oriented in the basal plane. Hence, Nd 6 Fe 13 Si shows a continuous magnetic spin-reorientation from axial towards basal alignment upon cooling.

A comparative Mössbauer spectral study of the electronic and magnetic properties of Nd6Fe13Ag and Nd6Fe13AgH13

“…110 K leads to a dramatic change in the Mössbauer spectra, a change that requires both of the above models for adequate fits. As reported earlier [8] the magnetization of Nd 6 Fe 13 Ag is basal and, as may be seen in Fig. 1, the Mössbauer spectra are fit excellently with five sextets.…”

“…1, the Mössbauer spectra are fit excellently with five sextets. In these fits the isomer shifts of the 16k and 16k sites have been constrained to be identical and, in the initial [8] fits of the Nd 6 Fe 13 Ag spectra, the relative areas of the five sextets were constrained to the magnetic degeneracies of the iron sites, i.e., 4:8:8:16:16, and it was assumed that there was no texture in the absorber. In the fits shown in Fig.…”

“…The sample of Nd 6 Fe 13 Ag was prepared by arc melting starting materials of at least 99.9% purity and is the same sample as was used in earlier studies [7,8,10]. After arc melting the sample was wrapped in tantalum foil, sealed in an evacuated quartz tube, annealed for 4 weeks at 900 K, and quenched to room temperature.…”

“…The magnetic properties of R 6 Fe 13 X with various X elements have been studied [3][4][5][6][7][8][9] and the properties of Nd 6 Fe 13 Si have proven [3,8,10,11] to be unusually interesting because it exhibits a magnetic spin reorientation upon cooling below 110 K. Because of the spin reorientation observed in Nd 6 Fe 13 Si, it is essential to have a good understanding of the Mössbauer spectra of the various Nd 6 Fe 13 X compounds. Fortunately, there have been several very useful earlier Mössbauer spectral studies of Nd 6 Fe 13 X where X is Cu [6], Ag [4,9], Au [4,7], Ge [12], In [13], Tl [13], Sn [9,13] and Pb [13], studies which indicate that the spectra are very sensitive to both the local environments and the nature of the magnetic anisotropy, i.e., axial or basal.…”

Magnetic properties ofR6Fe13−xM1+xGroot1, Buschow2, Boer3 1998Phys. Rev. BSelf Cite515200View full textAdd to dashboardCite

“…Assuming the Nd moment to have its free-ion value, an average Fe moment of 1.8 B is derived. This is somewhat lower then data from Mössbauer spectroscopy 20,5 giving an average Fe moment of 2.0 B at low temperatures ͓derived from the hyperfine splitting using a conversion factor of 1.48 T/ B ͑Ref. 21͔͒.…”