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Anisotropy-Tuned Magnetic Order in Pyrochlore Iridates
E Lefrançois1,2,3, V Simonet2,3, R Ballou2,3
1Institut Laue Langevin, CS 20156, 38042 Grenoble, France.
Physical Review Letters
|July 22, 2015
Summary
Magnetic ordering in iridium pyrochlores Er2Ir2O7 and Tb2Ir2O7 differs due to rare-earth anisotropy. Tb2Ir2O7 shows all-in-all-out order, while Er2Ir2O7 exhibits spin freezing.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Magnetism
Background:
- Rare-earth pyrochlores (A2B2O7) exhibit complex magnetic phenomena.
- Iridium-based pyrochlores are known for exotic magnetic ordering.
- Understanding magnetic interactions in these materials is crucial for novel electronic applications.
Purpose of the Study:
- To investigate the magnetic behavior of Er2Ir2O7 and Tb2Ir2O7.
- To elucidate the role of the iridium sublattice and rare-earth anisotropy.
- To determine the nature of magnetic ordering in these pyrochlores.
Main Methods:
- Magnetization measurements were performed on polycrystalline samples.
- Neutron diffraction was utilized to probe magnetic structures.
- Thermomagnetic hysteresis was analyzed to identify magnetic transitions.
Main Results:
- Both Er2Ir2O7 and Tb2Ir2O7 show magnetic transitions at 140 K and 130 K, respectively, linked to Ir sublattice ordering.
- Tb2Ir2O7 exhibits all-in-all-out magnetic ordering of Tb moments below 40 K, driven by the Ir molecular field.
- Er2Ir2O7 shows no long-range magnetic order on the Er sublattice down to 0.6 K, with spin freezing detected.
Conclusions:
- The contrasting magnetic behaviors arise from the interplay between the Ir molecular field and rare-earth single-ion anisotropy.
- The findings strongly support the existence of an all-in-all-out iridium magnetic order in these pyrochlores.
- Anisotropy differences between Terbium and Erbium ions dictate the magnetic ordering pathways.
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