Neutron diffraction study of the magnetic structures of CeMn{sub 2}Ge{sub 2} and CeMn{sub 2}Si{sub 2}

Technical Report · Sun Dec 31 04:00:00 EST 1995

DOI:https://doi.org/10.2172/201778· OSTI ID:201778

Fernandez-Baca, J A; Chakoumakos, B C ^[1]; Hill, P; Ali, N ^[2]

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1. Oak Ridge National Lab., TN (United States). Solid State Div.
2. Southern Illinois Univ., Carbondale, IL (United States). Dept. of Physics

The magnetic properties of the layered compounds of the form RMn{sub 2}X{sub 2} (R = Rare Earth, X = Si, Ge) have been thought to be sensitive to the intralayer Mn-Mn distance. Thus it has been reported that the Mn moments in CeMn{sub 2}Si{sub 2} are aligned antiferromagnetically (AF) below T{sub N} = 380K, while the Mn moments in CeMn{sub 2}Ge{sub 2} are ferromagnetic (FM) below T{sub C} = 316K. Recently, however, there has been some debate about the actual magnetic structures of this family of compounds, and for this reason the authors have performed high-resolution neutron powder diffraction measurements on these compounds for temperatures between 12K and 550K. The measurements indicate that at high temperatures both compounds are paramagnetic. Below T{sub N} = 380K CeMn{sub 2}Si{sub 2} becomes a collinear AF, with a structure similar to that reported by Siek et al. in which the magnetic propagation vector is {tau} = (0 0 1). CeMn{sub 2}Ge{sub 2} on the other hand, exhibits two different magnetic transitions. At T{sub N} {approx} 415K there is a transition to a collinear AF phase characterized by the commensurate propagation wavevector {tau} = (1 0 1). At T{sub C} = 318K there is a transition to a conical structure with a ferromagnetic component along the c-axis and a helical component in the ab plane. The helical component is characterized by the incommensurate propagation vector {tau} = (1 0 1-q{sub z}), where q{sub z} is temperature dependent. These findings are consistent with the recent results of Welter et al.

• Research Organization: Oak Ridge National Lab., TN (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 201778
• Report Number(s): CONF-951101--9; ON: DE96005656
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
66 PHYSICS
CERIUM ALLOYS
EXPERIMENTAL DATA
GERMANIUM ALLOYS
MAGNETIC MOMENTS
MAGNETIC PROPERTIES
MAGNETISM
MANGANESE ALLOYS
NEUTRON DIFFRACTION
SILICON ALLOYS
TEMPERATURE DEPENDENCE