Nanosized helical magnetic domains in strongly frustrated
- Colorado State Univ., Fort Collins, CO (United States)
Fe3PO4O3 forms a noncentrosymmetric lattice structure (space group R3m) comprising triangular motifs of Fe3+ coupled by strong antiferromagnetic interactions ( | ΘCW | > 900 K). Neutron diffraction from polycrystalline samples shows that strong frustration eventually gives way to an ordered helical incommensurate structure below TN =163 K, with the helical axis in the hexagonal ab plane and a modulation length to ~86 Å. The magnetic structure consists of an unusual needlelike correlation volume that extends past 900 Å along the hexagonal c axis but is limited to ~70 Å in the a b plane, despite the three-dimensional nature of the magnetic sublattice topology. The small in-plane correlation length, which persists to at least T = TN/40 , indicates a robust blocking of long-range order of the helical magnetic structure, and therefore stable domain walls, or other defect spin textures, must be abundant in Fe3PO4O3. Temperature-dependent neutron powder diffraction reveals small negative thermal expansion below TN. No change in lattice symmetry is observed on cooling through TN, as revealed by high-resolution synchrotron x-ray diffraction. The previously reported reduced moment of the Fe3+ ions (S = 5/2), μ ~ 4.2 μB, is confirmed here through magnetization studies of a magnetically diluted solid solution series of compounds, Fe(3–x)GaxPO4O3, and is consistent with the refined magnetic moment from neutron diffraction 4.14(2) μB. Here, we attribute the reduced moment to a modified spin density distribution arising from ligand charge transfer in this insulating oxide.
- Research Organization:
- Argonne National Laboratory (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- OSTI ID:
- 1322370
- Alternate ID(s):
- OSTI ID: 1224362
- Journal Information:
- Physical Review. B, Condensed Matter and Materials Physics, Vol. 92, Issue 13; ISSN 1098-0121
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- ENGLISH
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