Neutron-scattering studies of magnetic excitations in La1−xSrxMnO3: A dimensional crossover

Hirota, K.; Kaneko, Nobu‐Hisa; Nishizawa, Akinori; Endoh, Y.; Martin, Michael; Shirane, G.

doi:10.1016/s0921-4526(97)00039-2

Cited by 29 publications

(15 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Its smallness and the isotropy in J, however, suggest that the electron distribution is more isotropic than that in the LaMnO 3 -type OO. Similar situation is realized in the FM-I phase of La 0.88 Sr 0.12 MnO 3 , 20,32 where the staggered orbital ordering of (|d 3z 2 −r 2 ± |d x 2 −y 2 )/ √ 2 is proposed. 20,21 In the next section, we will theoretically investigate the orbital state Pr 1−x Ca x MnO 3 and construct the spin and orbital phase diagram.…”

Section: B Character Of the Homogeneous Fm-i Statesupporting

confidence: 64%

Ferromagnetic insulating phase in Pr1$minus;xCaxMnO3

Kajimoto

2003

Physica B: Condensed Matter

View full text Add to dashboard Cite

A ferromagnetic insulating (FM-I) state in Pr0.75Ca0.25MnO3 has been studied by neutron scattering experiment and theoretical calculation. The insulating behavior is robust against an external magnetic field, and is ascribed to neither the phase separation between a ferromagnetic metallic (FM-M) phase and a non-ferromagnetic insulating one, nor the charge ordering. We found that the Jahn-Teller type lattice distortion is much weaker than PrMnO3 and the magnetic interaction is almost isotropic. These features resembles the ferromagnetic metallic state of manganites, but the spin exchange interaction J is much reduced compared to the FM-M state. The theoretical calculation based on the staggered type orbital order well reproduces several features of the spin and orbital state in the FM-I phase.

show abstract

Section: B Character Of the Homogeneous Fm-i Statesupporting

confidence: 64%

Ferromagnetic insulating phase in Pr1$minus;xCaxMnO3

Kajimoto

2003

Physica B: Condensed Matter

View full text Add to dashboard Cite

show abstract

“…This isotropic behavior of magnetization is consistent with the isotropic spin-wave dispersion measured by neutron scattering. 25 It should be also noticed that no significant contribution by the small antiferromagnetic ͑AFM͒ components observed in the neutron-scattering experiments appears in these magnetization curves. 18,25 These facts indicate that the FI phase appearing below T OO can be essentially considered as an isotropic three-dimensional ͑3D͒ ferromagneic state.…”

Section: B Magnetizationmentioning

confidence: 71%

Two ferromagnetic phases inLa1−xSrxMnO
Nojiri
¹
,
Kaneko
²
,
Motokawa
³

et al. 1999
Phys. Rev. B
Self Cite
72
4
29
2
View full text Add to dashboard Cite

It was discovered in La 1Ϫx Sr x MnO 3 (xϳ1/8) that a field-induced phase transition occurs from a ferromagnetic metal ͑FM͒ phase to a ferromagnetic insulator ͑FI͒ phase. The magnetization shows a sharp jump at the transition field accompanied by a remarkable increase of magnetoresistance. Striction measurements clarified that this transition is associated with the structural change from a Jahn-Teller ͑JT͒ distorted orthorhombic phase to a pseudocubic phase. These results evidently show that the FI phase with a pseudocubic symmetry is more stable in high fields than the FM phase due to the double-exchange interaction. The driving force of this transition is explained by the enhancement of the ferromagnetic superexchange interaction induced by an antiferromagnetic-type orbital ordering in the pseudocubic phase, which was recently found in the anomalous x-ray scattering experiments. ͓S0163-1829͑99͒06129-9͔

show abstract

“…[28], and the other data from Ref. [29]. It is evident that D(0) is simply proportional to x, independent of whether the ground state is a ferromagnetic insulator (e.g., x = 0.15), or a ferromagnetic metal (e.g., x = 0.175, 0.20, 0.30).…”

mentioning

confidence: 62%

Double exchange and the cause of ferromagnetism in doped manganites

Zhao

2000

Phys. Rev. B

View full text Add to dashboard Cite

The coexistence of ferromagnetism and metallic conduction in doped manganites has long been explained by a double-exchange model in which the ferromagnetic exchange arises from the carrier hopping. We evaluate the zero-temperature spin stiffness D(0) and the Curie temperature TC on the basis of the double-exchange model using the measured values of the bare bandwidth W and the Hund's rule coupling JH . The calculated D(0) and TC values are too small compared with the observed ones even in the absence of interactions. A realistic onsite interorbital Coulomb repulsion can reduce D(0) substantially in the case of a 2-orbital model. Furthermore, experiment shows that D(0) is simply proportional to x in La1−xSrxMnO3 system, independent of whether the ground state is a ferromagnetic insulator or metal. These results strongly suggest that the ferromagnetism in manganites does not originate from the double-exchange interaction. On the other hand, an alternative model based on the d − p exchange can semi-quantitatively explain the ferromagnetism of doped manganites at low temperatures.The discovery of "colossal" magnetoresistance in thin films of the manganite perovskites Re 1−x D x MnO 3 (Re = a rare-earth element, and D = a divalent element) [1,2] has stimulated extensive studies of magnetic, structural and transport properties of these materials [3]. The coexistence of ferromagnetism and metallic conduction has long been explained by the double-exchange (DE) model [4,5], where the effective hopping for the manganese 3d conduction electrons varies with the angle between the manganese core electrons due to a strong Hund's coupling. However, Millis et al. [6] proposed that, in addition to the double-exchange, a strong electron-phonon interaction arising from a strong Jahn-Teller effect should be involved to explain the basic physics of manganites. In this modified model, the primary cause of the ferromagnetism of doped manganites is still the double-exchange interaction.In the DE model, it is implicitly assumed that doped carriers are Mn e g electrons. This assumption is not justified by both electron-energy-loss [7] and photoemission spectroscopies [8], which have shown that the ferromagnetic manganites (x<0.4) are doped charge-transfer insulators with carriers mainly residing on the oxygen orbitals. Now a question arises: Does the ferromagnetism of doped manganites really originate from the DE interaction? If not, what causes the ferromagnetism in these compounds? One way to address this fundamental issue is to make a quantitative comparison between the predicted properties of the DE model and experiment.There are two important parameters in the DE model, namely, the bare bandwidth W of the e g bands, and the Hund's rule coupling J H between e g and t 2g electrons. These parameters are related to an optical transition between the exchange splitted e g bands [9,10], and thus can be determined from optical data. With these unbiased parameters, one can calculate the zero-temperature spin stiffness D(0) and T C . Here D(0)...

show abstract

Neutron-scattering studies of magnetic excitations in La1−xSrxMnO3: A dimensional crossover

Cited by 29 publications

References 5 publications

Ferromagnetic insulating phase in Pr1$minus;xCaxMnO3

Ferromagnetic insulating phase in Pr1$minus;xCaxMnO3

Two ferromagnetic phases inLa1−xSrxMnO
Nojiri
¹
,
Kaneko
²
,
Motokawa
³

et al. 1999
Phys. Rev. B
Self Cite
72
4
29
2
View full text Add to dashboard Cite

Double exchange and the cause of ferromagnetism in doped manganites

Contact Info

Product

Resources

About

Neutron-scattering studies of magnetic excitations in La1−xSrxMnO3: A dimensional crossover

Cited by 29 publications

References 5 publications

Ferromagnetic insulating phase in Pr1$minus;xCaxMnO3

Ferromagnetic insulating phase in Pr1$minus;xCaxMnO3

Two ferromagnetic phases inLa1−xSrxMnONojiri1, Kaneko2, Motokawa3 et al. 1999Phys. Rev. BSelf Cite724292View full textAdd to dashboardCite

Double exchange and the cause of ferromagnetism in doped manganites

Contact Info

Product

Resources

About

Two ferromagnetic phases inLa1−xSrxMnO
Nojiri
¹
,
Kaneko
²
,
Motokawa
³

et al. 1999
Phys. Rev. B
Self Cite
72
4
29
2
View full text Add to dashboard Cite