Spin-1 Pyrochlore Ruthenate
Spin-1 Pyrochlore Ruthenate
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Competing magnetic orders
Competing magnetic orders
- Pyrochlores with magnetic frustration provide a suitable material platform to study exotic electronic phases.
- Pyrochlores with magnetic frustration provide a suitable material platform to study exotic electronic phases.
- A Higgs-like magnetic fluctuation was recently observed in spin-1 pyrochlore ruthenate, Nd2Ru2O7, without knowing its origin due to a long-term debate on the Ru magnetic order.
- A Higgs-like magnetic fluctuation was recently observed in spin-1 pyrochlore ruthenate, Nd2Ru2O7, without knowing its origin due to a long-term debate on the Ru magnetic order.
- The competing magnetic orders are found in this study via neutron diffraction on high-quality polycrystalline samples nearly without a magnetic impurity phase.
- The competing magnetic orders are found in this study via neutron diffraction on high-quality polycrystalline samples nearly without a magnetic impurity phase.
- The magnetic excitation in Raman could be understood by the selection of the ground state from competing magnetic orders.
- The magnetic excitation in Raman could be understood by the selection of the ground state from competing magnetic orders.
3d-based Kitaev Quantum Spin Liquid
3d-based Kitaev Quantum Spin Liquid
Field-induced dichotomous electronic state
Field-induced dichotomous electronic state
- Na2Co2TeO6 is currently the most promising Kitaev quantum spin liquid candidate in the 3d-based system.
- Na2Co2TeO6 is currently the most promising Kitaev quantum spin liquid candidate in the 3d-based system.
- A revised crystal structure is proposed that is more favorable to the spin liquid under field.
- A revised crystal structure is proposed that is more favorable to the spin liquid under field.
- The fundamental nature of this field-induced state is revealed as dichotomic: concurrent low-energy magnons and high-energy spinons.
- The fundamental nature of this field-induced state is revealed as dichotomic: concurrent low-energy magnons and high-energy spinons.
[17] S. Lee, K. Y. Choi*, S. Choi* et al., Physical Review B 113, 134411 (2026) (Editors’ Suggestion). (highlighted by ISIS).
[17] S. Lee, K. Y. Choi*, S. Choi* et al., Physical Review B 113, 134411 (2026) (Editors’ Suggestion). (highlighted by ISIS).
Machine Learning-driven Structural Analysis
Machine Learning-driven Structural Analysis
Automation of Rietveld Refinement
Automation of Rietveld Refinement
- X-ray diffraction is likely the most widely employed method for characterizing samples across various scientific disciplines and industries.
- X-ray diffraction is likely the most widely employed method for characterizing samples across various scientific disciplines and industries.
- Data analysis has primarily depended on labor-intensive manual processes to date.
- Data analysis has primarily depended on labor-intensive manual processes to date.
- To overcome these fundamental limitations, we propose a new conceptual and computational method by developing the program.
- To overcome these fundamental limitations, we propose a new conceptual and computational method by developing the program.
- Our novel method can be applied to a diverse range of materials, offering significant advantages for industries and laboratories that require efficient and systematic analysis of large volumes of data.
- Our novel method can be applied to a diverse range of materials, offering significant advantages for industries and laboratories that require efficient and systematic analysis of large volumes of data.
Polar Altermagnets with Multiferroicity
Polar Altermagnets with Multiferroicity
Controlled growths of polar multiferroic altermagnets
Controlled growths of polar multiferroic altermagnets
- Chemical vapour transport growth is optimized for polar altermagnets, Fe2Mo3O8 and NiZnMo3O8
- Chemical vapour transport growth is optimized for polar altermagnets, Fe2Mo3O8 and NiZnMo3O8
- Finding the transport agent density as a primary factor
- Finding the transport agent density as a primary factor
- Successful growth of large single crystals: i.e., 10 times larger than normal sizes
- Successful growth of large single crystals: i.e., 10 times larger than normal sizes
- Comprehensive characterizations using single-crystal XRD, Laue, magnetic susceptibility, Raman spectroscopy
- Comprehensive characterizations using single-crystal XRD, Laue, magnetic susceptibility, Raman spectroscopy
- Enabling the detailed examinations of largely unexplored multiferroic altermagnets and allowing the manipulation of altermagnetic and multiferroic properties using nonmagnetic Zn ions in the honeycomb layer.
- Enabling the detailed examinations of largely unexplored multiferroic altermagnets and allowing the manipulation of altermagnetic and multiferroic properties using nonmagnetic Zn ions in the honeycomb layer.
Partial Molecular Orbitals in Trimer-based Magnets
Partial Molecular Orbitals in Trimer-based Magnets
Experimental finding on partial molecular orbital, a new type of correlated electrons, supported by DFT results
Experimental finding on partial molecular orbital, a new type of correlated electrons, supported by DFT results
- A new proposal for partial molecular orbital state [13], a new correlated electron state, by experiment and theory
- A new proposal for partial molecular orbital state [13], a new correlated electron state, by experiment and theory
- Optimized samples growths of new Ba4TaMn3O12 and improved quality of Ba4NbMn3O12 powder
- Optimized samples growths of new Ba4TaMn3O12 and improved quality of Ba4NbMn3O12 powder
- Magnetic susceptibility and heat capacity results propose an unusual partial molecular orbital state in the Mn-trimer, confirmed by DFT calculations
- Magnetic susceptibility and heat capacity results propose an unusual partial molecular orbital state in the Mn-trimer, confirmed by DFT calculations
- Unusual dichotomy of localized and d-localized 3d electrons, potentially useful in developing novel electronic devices
- Unusual dichotomy of localized and d-localized 3d electrons, potentially useful in developing novel electronic devices
Insulator Metal Transitions in Frustrated Cubic Lattices
Insulator Metal Transitions in Frustrated Cubic Lattices
Revealing the p-d orbital hybridization on quantum phase transition in the frustrated cubic nickelate magnet
Revealing the p-d orbital hybridization on quantum phase transition in the frustrated cubic nickelate magnet
- Observation of a subtle change in the structure via the electronic insulator-metal transition in archetypal NiS2-xSex [10]
- Observation of a subtle change in the structure via the electronic insulator-metal transition in archetypal NiS2-xSex [10]
- Combined powder x-ray diffraction and single-crystal Raman scattering on a wide range of the Se doping at varying temperatures
- Combined powder x-ray diffraction and single-crystal Raman scattering on a wide range of the Se doping at varying temperatures
- Confirmation of effect of p-d orbital coupling, verifying a rare case of a bandwidth-controlled electronic transition without a structural transition
- Confirmation of effect of p-d orbital coupling, verifying a rare case of a bandwidth-controlled electronic transition without a structural transition
Novel Magnetoelectricity in Buckled Honeycomb Lattices
Novel Magnetoelectricity in Buckled Honeycomb Lattices
Determining a noncollinear magnetic order of the buckled honeycomb, explaining a new type of magnetoelectricity
Determining a noncollinear magnetic order of the buckled honeycomb, explaining a new type of magnetoelectricity
- Discovery of the novel noncollinear magnetic order in a newly-interested magnetoelectric Co4Ta2O9 [9] in the new magnetic space group, explaining the main feature of unusual electric polarisation. It has a prospect for examining toroic moments and dichroism with the potential to develop multifunctional devices.
- Discovery of the novel noncollinear magnetic order in a newly-interested magnetoelectric Co4Ta2O9 [9] in the new magnetic space group, explaining the main feature of unusual electric polarisation. It has a prospect for examining toroic moments and dichroism with the potential to develop multifunctional devices.
- The first observation of the P1 magnetic space group is made with nearly isotropic ferromagnetic moment at lower temperatures in high-quality Co4Ta2O9 [11] single crystals, providing a tuning parameter to the coupled multiferroic state.
- The first observation of the P1 magnetic space group is made with nearly isotropic ferromagnetic moment at lower temperatures in high-quality Co4Ta2O9 [11] single crystals, providing a tuning parameter to the coupled multiferroic state.
[9] S. Choi*, V. Kiryukhin et al., Physical Review B 102, 214404 (2020) (Editors’ Suggestion): Highlighted by the ISIS Neutron and Muon Source.
[9] S. Choi*, V. Kiryukhin et al., Physical Review B 102, 214404 (2020) (Editors’ Suggestion): Highlighted by the ISIS Neutron and Muon Source.
Determination of a noncollinear magnetic order of a new magnetoelectric material and its anisotropy
Determination of a noncollinear magnetic order of a new magnetoelectric material and its anisotropy
- Via powder and single-crystal neutron diffraction, determination of an accurate noncollinear magnetic order of Ni2Mo3O8 [12] is made, whose anisotropy is confirmed by direction-dependent magnetic susceptibility. Based on the determined magnetic order, the local magnetoelectric tensor analysis predicts the unexplored in-plane polarization. Magnetic order indicates a possible mixture of the origin of the magnetoelectricity, the spin-current, and p-d hybridization mechanisms.
- Via powder and single-crystal neutron diffraction, determination of an accurate noncollinear magnetic order of Ni2Mo3O8 [12] is made, whose anisotropy is confirmed by direction-dependent magnetic susceptibility. Based on the determined magnetic order, the local magnetoelectric tensor analysis predicts the unexplored in-plane polarization. Magnetic order indicates a possible mixture of the origin of the magnetoelectricity, the spin-current, and p-d hybridization mechanisms.
- Accurate determination of the magnetic ground state of multiferroic Fe4Nb2O9 [15] in a very low symmetry via neutron diffraction and group theory, resolving the debate and explaining its unusual magnetoelectricity.
- Accurate determination of the magnetic ground state of multiferroic Fe4Nb2O9 [15] in a very low symmetry via neutron diffraction and group theory, resolving the debate and explaining its unusual magnetoelectricity.
5d-based Kitaev Magnetism in Honeycomb Lattices
5d-based Kitaev Magnetism in Honeycomb Lattices
Testing the Kitaev interaction in the honeycomb Na2IrO3 magnet with neutrons and spin-wave calculations
Testing the Kitaev interaction in the honeycomb Na2IrO3 magnet with neutrons and spin-wave calculations
- Direct observation of magnetic excitations from any iridates for the first time by inelastic neutron scattering on Na2IrO3 [1]
- Direct observation of magnetic excitations from any iridates for the first time by inelastic neutron scattering on Na2IrO3 [1]
- Optimized experimental setup with the absorption simulation
- Optimized experimental setup with the absorption simulation
- New insight on spin dynamics of iridates
- New insight on spin dynamics of iridates
- Parameterize exchanges by testing various proposed theoretical models
- Parameterize exchanges by testing various proposed theoretical models
In-depth structural analysis of Kitaev materials
In-depth structural analysis of Kitaev materials
- Extensive structural analysis in prototypical Kitaev iridates
- Extensive structural analysis in prototypical Kitaev iridates
- Single-crystal x-ray diffraction with stacking faults analysis
- Single-crystal x-ray diffraction with stacking faults analysis
- Na2IrO3 [1, 2], (Na,Li)2IrO3 [3], beta-Li2IrO3 [7], gamma-Li2IrO3 [4]
- Na2IrO3 [1, 2], (Na,Li)2IrO3 [3], beta-Li2IrO3 [7], gamma-Li2IrO3 [4]
- Vital information to validate a strength of a Kitaev term in real materials that can give ideas to stabilize a Kitaev quantum spin liquid
- Vital information to validate a strength of a Kitaev term in real materials that can give ideas to stabilize a Kitaev quantum spin liquid
Exploring spin dynamics and field-induced magnetic phase transition in the honeycomb Kitaev magnet alpha-Li2IrO3
Exploring spin dynamics and field-induced magnetic phase transition in the honeycomb Kitaev magnet alpha-Li2IrO3
- Observation of sharply dispersive low-energy spin dynamics on alpha-Li2IrO3 [6] with inelastic neutron scattering
- Observation of sharply dispersive low-energy spin dynamics on alpha-Li2IrO3 [6] with inelastic neutron scattering
- Goldstone and gapped excitations from a counterrotating noncoplanar magnetic order [5] by magnetic resonant x-ray diffraction and muon
- Goldstone and gapped excitations from a counterrotating noncoplanar magnetic order [5] by magnetic resonant x-ray diffraction and muon
- Gapped excitation confirmed by high-field magnetization, a novel field-induced magnetic phase transition
- Gapped excitation confirmed by high-field magnetization, a novel field-induced magnetic phase transition
Probing a competition between intermetallic covalency and formation of moments in the hyperhoneycomb iridate
Probing a competition between intermetallic covalency and formation of moments in the hyperhoneycomb iridate
- A nontrivial counterrotating noncoplanar incommensurate magnetic order of beta-Li2IrO3, a rare three-dimensional Kitaev material, determined by neutron and magnetic resonant x-ray diffraction [7] at ambient pressure
- A nontrivial counterrotating noncoplanar incommensurate magnetic order of beta-Li2IrO3, a rare three-dimensional Kitaev material, determined by neutron and magnetic resonant x-ray diffraction [7] at ambient pressure
- Observation of a pressure-induced structural transition via high-pressure Raman [8] at room temperature
- Observation of a pressure-induced structural transition via high-pressure Raman [8] at room temperature
- The evidence of the competition between the covalency of the 5d orbitals and magnetism
- The evidence of the competition between the covalency of the 5d orbitals and magnetism
- Implication as the strong connectivity of its electronic structure to an underlying crystal structure
- Implication as the strong connectivity of its electronic structure to an underlying crystal structure
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