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Do, S.-H.*; Kaneko, Koji; Kajimoto, Ryoichi; Kamazawa, Kazuya*; Stone, M. B.*; Lin, J. Y. Y.*; Ito, Shinichi*; Masuda, Takatsugu*; Samolyuk, G. D.*; Dagotto, E.*; et al.
Physical Review B, 105(18), p.L180403_1 - L180403_6, 2022/05
Times Cited Count：12 Percentile：87.73(Materials Science, Multidisciplinary)
-orbital Hubbard modelXavier, J. C.*; Onishi, Hiroaki; Hotta, Takashi; Dagotto, E.*
Physical Review B, 73(1), p.014405_1 - 014405_9, 2006/01
Times Cited Count：9 Percentile：41.55(Materials Science, Multidisciplinary)We present the zero-temperature phase diagram of the one-dimensional -orbital Hubbard model, by using the density-matrix renormalization group and Lanczos techniques. Emphasis is given to the case for the electron density 
=5, of relevance to Co-based compounds. Several other cases for electron densities between =3 and 6 are also studied. At =5, our results indicate a first-order transition between a paramagnetic (PM) insulator phase and a ferromagnetic (FM) state by tuning the Hund's coupling. The results also suggest a transition from the =5 PM insulator phase to a metallic regime by changing the electron density. The behavior of the spin, charge, and orbital correlation functions in the FM and PM states are discussed.
Hotta, Takashi; Dagotto, E.*
Physical Review Letters, 92(22), p.227201_1 - 227201_4, 2004/06
Times Cited Count：40 Percentile：80.89(Physics, Multidisciplinary)Ground-state properties of layered nickelates are investigated based on the orbital-degenerate Hubbard model coupled with lattice distortions, by using numerical techniques. The N
el state composed of spin 
=1 ions is confirmed in the undoped limit 
=0. At =1/2, novel antiferromagnetic states, called CE- and E-type phases, are found by increasing the Hund's coupling. (
/
)-type orbital ordering is predicted to occur in a checkerboard-type charge-ordered state. At =1/3, 
Coulombic and phononic interactions are found to be important, since the former stabilizes the spin stripe, while the latter leads to the striped charge-order.
Hotta, Takashi; Moraghebi, M.*; Feiguin, A.*; Moreo, A.*; Yunoki, Seiji*; Dagotto, E.*
Physical Review Letters, 90(24), p.247203_1 - 247203_4, 2003/06
Times Cited Count：83 Percentile：91.22(Physics, Multidisciplinary)Novel ground-state spin structures in undoped and doped manganites are here investigated based on the orbital-degenerate double-exchange model, by using mean-field and numerical techniques. In undoped manganites, a new antiferromagnetic (AFM) state, called the E-type phase, is found adjacent in parameter space to the A-type AFM phase. Its structure is in agreement with recent experimental results. This insulating E-AFM state is competing with a ferromagnetic metallic phase as well, suggesting that large magneto-resistant effects could exist even in undoped manganese oxides. For doped layered manganites, the phase diagram includes another new AFM phase of the 
-type. Experimental signatures of the new phases are discussed.
Hotta, Takashi; Dagotto, E.*
Physica B; Condensed Matter, 312-313(1-4), p.700 - 702, 2002/03
Times Cited Count：2 Percentile：14.65(Physics, Condensed Matter)The crucial role of the orbital degree of freedom is here discussed in order to understand the complex spin and charge structures of transition metal oxides. For manganites, it is shown that diagonal charge stripes in the ferromagnetic phase are induced by the staggered orbital ordered pattern, while for ruthenates, a novel orbital ordering is found to exist in the G-type antiferromagnetic structure, with a hole arrangement as recently observed in X-ray experiments.
Hotta, Takashi; Dagotto, E.*
Physical Review Letters, 88(1), p.017201_1 - 017201_4, 2002/01
Times Cited Count：80 Percentile：90(Physics, Multidisciplinary)The key role of the orbital degree of freedom to understand the magnetic properties of layered ruthenates is here discussed. In the G-type antiferromagnetic (AFM) phase of Ca
RuO
, recent X-ray experiments reported the presence of 0.5 hole per site in the 
orbital, while the 
and 
orbitals contain 1.5 holes. This unexpected hole distribution is explained by a novel state with orbital ordering (OO), stabilized by a combination of Coulomb interactions and lattice distortions. In addition, the rich phase diagram presented here suggests the possibility of large magnetoresistance effects, and predicts a new ferromagnetic OO phase in ruthenates.
Onishi, Hiroaki; Gonzalez, I.*; Melko, R.*; Dagotto, E.*
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Onishi, Hiroaki; Gonzalez, I.*; Melko, R.*; Dagotto, E.*
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Onishi, Hiroaki; Gonzalez, I.*; Melko, R.*; Dagotto, E.*
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Onishi, Hiroaki; Dagotto, E.*
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Onishi, Hiroaki; Dagotto, E.*
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Onishi, Hiroaki; Gonzalez, I.*; Melko, R.*; Dagotto, E.*
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Onishi, Hiroaki; Dagotto, E.*
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Onishi, Hiroaki; Dagotto, E.*
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no abstracts in English
Onishi, Hiroaki; Dagotto, E.*
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