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Critical magnetic transition in TbNi2Mn--magnetization and Mössbauer spectroscopy
J L Wang1, S J Campbell, S J Kennedy
1School of Physical, Environmental and Mathematical Sciences, The University of New South Wales, The Australian Defence Force Academy, Canberra ACT, Australia.
Summary
The study reveals strong magnetostructural coupling in TbNi(2)Mn(x), with optimal properties at x=1. Magnetic interactions are long-range, confirmed by critical exponent analysis and magnetic entropy calculations.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Magnetism
Background:
- Rare-earth intermetallic compounds like RNi(2)Mn exhibit complex magnetic behaviors.
- Understanding the interplay between structural and magnetic properties is crucial for developing new magnetic materials.
- Previous studies on RNi(2) and RMn(2) show different magnetic ordering temperatures compared to RNi(2)Mn.
Purpose of the Study:
- To investigate the structural and magnetic properties of the TbNi(2)Mn(x) series.
- To determine the nature of magnetic transitions and interactions within the material.
- To explore the relationship between composition, structure, and magnetic ordering.
Main Methods:
- X-ray diffraction for structural analysis.
- AC magnetic susceptibility and DC magnetization measurements (5-340 K, 0-5 T).
- (57)Fe Mössbauer spectroscopy (5-300 K) for local magnetic environment analysis.
Main Results:
- TbNi(2)Mn(x) crystallizes in the MgCu(2)-type structure.
- Lattice constant and Curie temperature (T(C)) show maxima at x = 1, indicating strong magnetostructural coupling.
- Magnetic transition at T(C) = 147 K is second order with critical exponents confirming long-range interactions.
Conclusions:
- The TbNi(2)Mn(x) series exhibits significant magnetostructural coupling, particularly at the x=1 composition.
- Long-range magnetic interactions are present despite structural complexities like mixed occupancies and vacancies.
- Mössbauer spectroscopy reveals distinct local magnetic environments above and below the Curie temperature.
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