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TitleMAGNETISM AND NEUTRON SCATTERING STUDIES OF RARE-EARTH CHROMATE SINGLE CRYSTALS
CreatorYinghao Zhu; Li HF(李海峰)
Subtype博士Phd
Thesis AdvisorHai-Feng Li
Date Issued2022-07
Degree GrantorUniversity of Macau
Place of ConferralUniversity of Macau
Abstract

Rare-earth transition-metal oxides (RETMOs) provide a strongly correlated electronic platform to couple the degrees of freedom including charge, spin, lattice, and orbital. Among various RETMOs compounds, rare-earth orthochromates with a chemical formula of RECrO3 are an interesting family of RETMOs materials. It was suggested that the interactions of 4f-3d spins play an important role in producing electric polarization below the Neel temperature, and the magnetoelectric effect may exist in the family of orthochromates. Moreover, there also exist various novel magnetic behaviors in the compound.
Firstly, high-quality RECrO3 single crystals were achieved with the laser-diode
floating-zone method. With the as-grown single crystals, in-house characterizations were performed to shed light on their properties. A systematic room-temperature Xray powder diffraction study was carried out on the as-grown single crystals. Structural refinements show that the RECrO3 single crystals belong to orthorhombic crystal system with Pbnm space group. We performed magnetization measurements as functions of temperature and external magnetic fields on as-grown single crystals, providing intrinsic magnetic properties. The t2g-eg hybridization was also investigated by firstprinciples calculations.
A neutron powder diffraction study of a single-crystalline YCrO3 compound was
carried out at a temperature range from 12 to 1200 K. The high-temperature (321–1200 K) structural information and magnetism indicate a strong magnetic frustration. Meanwhile, the neutron powder diffraction study at low temperatures (12–300 K) revealed its magnetic structure. Anisotropic magnetostriction effect was observed. An inelastic neutron scattering experiment was carried out based on a YCrO3 single crystal. A Linear spin-wave theoretical model considering Heisenberg exchange and DzyaloshinskiiMoriya interaction was built to study the magnon dispersion. The result indicates a strong spin-orbit coupling in the YCrO3 antiferromagnet.
The structural and magnetic properties of the GdCrO3 single crystal were carried
out. We observed the indications of the canted AFM structure of Cr3+ ions at TN-Cr, the spin reorientation of Cr3+ moments at TSR, and the formation of a long-range-ordered Gd3+ magnetic structure at TN-Gd. The magnetic phase diagrams of TN-Gd and TN-Cr are also studied. The GdCrO3 single crystal displays nice potential application on magnetic refrigeration.

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Document TypeThesis
CollectionINSTITUTE OF APPLIED PHYSICS AND MATERIALS ENGINEERING
Corresponding AuthorLi HF(李海峰)
Recommended Citation
GB/T 7714
Yinghao Zhu,Li HF. MAGNETISM AND NEUTRON SCATTERING STUDIES OF RARE-EARTH CHROMATE SINGLE CRYSTALS[D]. University of Macau. University of Macau,2022.
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