| 研究実績の概要 |
We have conducted further studies on the 2D Kagome Heisenberg antiferromagnetic MOF CuHHTP, including the magnetic field dependent susceptibility, heat capacity, NMR knight shift and ultralow temperature-high magnetic field magnetization. High-field (up to ~15T) magnetization didn't exhibit the 1/3 plateau as predicted by the theory, but special scaling behavior has been observed in the low field region. Meanwhile, the scaling could also be observed in the field dependent susceptibility, heat capacity and NMR knight shift measurement. By connecting the phase transition points that are obtained from the measurements, a new quantum phase diagram could be summarized for the CuHHTP MOF. Surprisingly, this MOF exhibits a quantum critical phase at 0 field and low temperature, and this critical phase dominates up to the 50% level of magnetization saturation and 70% of magnetic entropy.
We also prepared a series of Lanthanide oxalate salts Ln2(OX)3 10H2O, with Ln=Ce, Nd, Sm. These lanthanides adapted a strongly spin-orbital coupled Kramers cations, which could be considered as a Jeff=1/2 type of cation. Also, due to the crystal structure, these cations are aligned into honeycomb lattices. Therefore, these materials could be considered as Kitaev spin liquid candidates. MPMS results suggested Ce-ox doesn't exhibit magnetic ordering down to 2K. Ultralow temperature susceptibility measurement is being conducted.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
2: おおむね順調に進展している
理由
The physics study of CuHHTP gives us interesting results about the quantum phase diagram, which is rather novel in terms of solid-state physics.
For lanthanide complexes as Kitaev spin liquids, the samples could be prepared as relatively big crystals and the first stage of magnetic measurements looks promising. Therefore, the research plan is progressing rather smoothly.
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| 今後の研究の推進方策 |
In the following academic years, we will keep focusing on the studies of lanthanide oxalate honeycomb complexes as the candidate of Kitaev spin liquids. Susceptibility, heat capacity, neutron diffraction/scattering, muon resonance and other fundamental studies will be conducted to confirm the potential Kitaev state.
Furthermore, the axial dependent susceptibility or heat conductance could be performed on the single crystals of these materials, as these MOFs could be obtained as rather large single crystals. Since these materials may also be exfoliated as they adapted 2D structures, thin film devices will also be pursued for the lanthanide oxalate materials.
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