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Magnetism and magnetic structures of PrMn2Ge2-xSix
J L Wang1, S J Campbell, M Hofmann
1Bragg Institute, ANSTO, Lucas Heights, NSW 2234, Australia.
Summary
The study reveals that substituting silicon for germanium in PrMn2Ge2-xSix compounds alters magnetic properties, shifting from ferromagnetism to antiferromagnetism. Magnetovolume effects and re-entrant ferromagnetism were observed, influencing the magnetic phase diagram.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Magnetism
Background:
- PrMn2Ge2-xSix compounds are part of the RMn2X2 series, known for diverse magnetic behaviors.
- Understanding structure-property relationships is crucial for designing new magnetic materials.
Purpose of the Study:
- To investigate the structural and magnetic properties of PrMn2Ge2-xSix compounds.
- To establish the magnetic phase diagram as a function of Si concentration and temperature.
Main Methods:
- X-ray diffraction for structural analysis.
- Magnetic measurements (5-350 K).
- Neutron diffraction (3-480 K) for magnetic structure determination.
- Differential scanning calorimetry (300-500 K).
Main Results:
- Si substitution causes unit cell contraction and a magnetic crossover from ferromagnetism to antiferromagnetism.
- Non-linear lattice parameters indicate magnetovolume effects around x = 1.2.
- Re-entrant ferromagnetism observed in PrMn2Ge1.0Si1.0 and PrMn2Ge0.8Si1.2 compounds.
- Magnetic phase diagram constructed, showing dependence on Mn-Mn spacing.
Conclusions:
- The magnetic behavior is strongly tied to Mn-Mn interatomic distances.
- Increasing Si content reduces manganese magnetic moments due to shorter distances and altered hybridization.
- Pr site ferromagnetic ordering occurs for x < 1.6.
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