JOPSS - Search Results

Journal Articles

Evaluation of edge domains in giant magnetoresistive junctions

Frost, W.*; Seki, Takeshi*; Kubota, Takahide*; Ramos, R.*; Saito, Eiji; Takanashi, Koki*; Hirohata, Atsufumi*

Applied Physics Letters, 118(17), p.172405_1 - 172405_5, 2021/04

https://doi.org/10.1063/5.0049315

Times Cited Count：1 Percentile：7.45(Physics, Applied)

Journal Articles

Unveiling new magnetic phases of undoped and doped manganites

Hotta, Takashi; Moraghebi, M.*; Feiguin, A.*; Moreo, A.*; Yunoki, Seiji*; Dagotto, E.*

Physical Review Letters, 90(24), p.247203_1 - 247203_4, 2003/06

https://doi.org/10.1103/PhysRevLett.90.247203

Times Cited Count：83 Percentile：91.21(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 ${rm C_x E_{1-x}}$ -type. Experimental signatures of the new phases are discussed.

Journal Articles

Existence of a metallic ferromagnetic phase in models for undoped manganites

Hotta, Takashi

Physical Review B, 67(10), p.104428_1 - 104428_8, 2003/03

https://doi.org/10.1103/PhysRevB.67.104428

Times Cited Count：21 Percentile：68.18(Materials Science, Multidisciplinary)

The existence of a novel metal-insulator transition in the ferromagnetic state of models for undoped manganites is here discussed using numerical techniques applied to the $e_{rm g}$ -orbital degenerate Hubbard model tightly coupled with Jahn-Teller distortions. The ground-state phase diagram is presented in the plane defined by the electron-phonon coupling and Coulomb interaction . In contrast to the standard one-band Hubbard model for cuprates, the metallic phase is found to exist for finite values of both and in the present $e_{rm g}$ -orbital Hubbard model even at half-filling, due to the Fermi-surface topology which is incompatible with the staggered orbital ordering concomitant to the insulating phase. Based on the present results, a possible scenario for Colossal Magneto-Resistive effect is discussed in undoped manganites.

Journal Articles

Ferromagnetism and giant magnetoresistance in the rare-earth fullerides Eu $_{6-x}$ SrC $_{60}$

Ishii, Kenji; Fujiwara, Akihiko*; Suematsu, Hiroyoshi*; Kubozono, Yoshihiro*

Physical Review B, 65(13), p.134431_1 - 134431_6, 2002/03

https://doi.org/10.1103/PhysRevB.65.134431

Times Cited Count：32 Percentile：78.13(Materials Science, Multidisciplinary)

We have studied crystal structure, magnetism and electric transport properties of a europium fulleride EuC $_{60}$ and its Sr-substituted compounds, Eu $_{6-x}$ SrC $_{60}$ . They have a structure, which is an isostructure of other C $_{60}$ ( represents an alkali atom or an alkaline earth atom). Magnetic measurements revealed that magnetic moment is ascribed to the divalent europium atom with = 7/2 spin, and a ferromagnetic transition was observed at = 10 - 14 K. In EuC $_{60}$ , we also confirm the ferromagnetic transition by heat capacity measurement. The striking feature in Eu $_{6-x}$ SrC $_{60}$ is very large negative magnetoresistance at low temperature; the resistivity ratio ( = 9 T)/( = 0 T) reaches almost 10 $^{-3}$ at 1 K in EuC $_{60}$ . Such large magnetoresistance is the manifestation of a strong - interaction between conduction carriers on C $_{60}$ and 4 electrons of Eu.