A Study of the Intermetallic Compounds of Gold and Manganese through the Use of the 197Au Mössbauer Effect at 4.2°K and as a Function of Pressure
Abstract
The Mössbauer spectra of the 197Au nuclei in Au, Au4Mn, Au3Mn, Au2Mn, AuMn, AuMn3, and dilute alloys of Au in Mn have been measured at 4.2 °K. The isomer shift, magnetic dipole, and electric quadrupole splittings observed for these alloys are discussed in terms of the magnetic and crystalline structure. In these ordered gold-manganese alloys, the isomer shift as a function of composition departs widely from the linearity often observed for gold solid-solution alloys. For Au2Mn, we find an effective field at the 197Au nucleus of 1590 kG as well as a large quadrupole coupling. The spectrum we observe for Au2Mn is consistent with the helical magnetic structure generally assumed for this alloy. A detailed analysis of this spectrum gives the magnetic moment μ*=0. 415+/-0. 004 μN for the 77.345-keV state of 197Au, subject to a correction for the hyperfine-structure anomaly. For Au2Mn, Mössbauer measurements have also been made as a function of pressure between 0 and 46 kbars. A 7% increase in the magnitude of the effective field at the 197Au nucleus is observed between 0 and 30 kbar. This may be due to the uncoiling of the Mn spin helix observed by other workers in this pressure range.
- Publication:
-
Physical Review B
- Pub Date:
- October 1970
- DOI:
- 10.1103/PhysRevB.2.2440
- Bibcode:
- 1970PhRvB...2.2440P