Development and loss of ferromagnetism controlled by the interplay of Ge concentration and Mn vacancies in structurally modulated Y{sub 4}Mn{sub 1-x}Ga{sub 12-y}Ge{sub y}.
- Intense Pulsed Neutron Source
The cubic intermetallic phase Y{sub 4}Mn{sub 1-x}Ga{sub 12-y}Ge{sub y} (x = 0-0.26, y = 0-4.0) has been isolated from a molten gallium flux reaction. It presents a rare example of a system where ferromagnetism can be induced by controlling the vacancies of the magnetic centers. The Y{sub 4}PdGa{sub 12} type crystal structure is made up of a corner-sharing octahedral network of Ga and Ge atoms with Mn atoms at the centers of half the octahedra and Y atoms in the voids. At the highest Ge concentration, y = 4.0, the Mn site is nearly fully occupied, x = 0.05, and the samples are paramagnetic. At a lower Ge concentration, y = 1.0, Mn deficiency develops with x = 0.10. Surprisingly, strong ferromagnetism is observed with T{sub c} = 223 K. When Ge is excluded, y = 0, Mn is substantially deficient at x = 0.26 and ferromagnetism is maintained with a T{sub c} of {approx}160 K. In addition, a 6-fold modulated superstructure appears owing to an ordered slab-like segregation of Mn atoms and vacancies. Corresponding bond distortions propagate throughout the octahedral Ga network. Structure-property relationships are examined with X-ray and neutron diffraction, magnetic susceptibility, and electrical resistivity measurements.
- Research Organization:
- Argonne National Laboratory (ANL)
- Sponsoring Organization:
- SC
- DOE Contract Number:
- AC02-06CH11357
- OSTI ID:
- 1008302
- Report Number(s):
- ANL/MSD/JA-69084
- Journal Information:
- J. Am. Chem. Soc., Journal Name: J. Am. Chem. Soc. Journal Issue: 26 ; Jun. 2010 Vol. 132; ISSN 0002-7863
- Country of Publication:
- United States
- Language:
- ENGLISH
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