Abstract
Results of crystal structure, microstructure, and magnetic properties studies of arcmelted and annealed ZrFe 6Al 6, ZrFe 5.5Al 6.5, ZrFe 5Al 7, HfFe 6Al 6, HfFe 5.5Al 6.5, and HfFe 5Al 7 are reported. These compounds adopt the ThMn 12 structure-type (space group 139, I4/mmm), like their more common rare-earth analogues. Analysis of powder x-ray diffraction data show that the 8f site is occupied by Fe, the 8i site by Al, and the 8j site by a mixture of Fe and Al. All of the compounds undergo a ferromagnetic transition at temperatures ranging from 170 to 270 K. Three effects on the magnetic properties are noted as the Fe content is increased: decrease in the Curie temperature, decrease in the magnetic moment per Fe at high fields, and the development of non-monotonic temperature dependence of the low-field magnetization below the Curie temperature. First principles calculations indicate a ferromagnetic ground state, but find antiferromagnetic interactions among Fe moments on 8j sites which is likely important in understanding the observed behavior.
Original language | English |
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Article number | 093918 |
Journal | Journal of Applied Physics |
Volume | 111 |
Issue number | 9 |
DOIs | |
State | Published - May 1 2012 |
Funding
This research was sponsored by the U.S. Department of Energy, Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies, as part of the Propulsion Materials Program.