Charge, orbital, and magnetic order in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Nd</mml:mi></mml:mrow><mml:mrow><mml:mn>0.5</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Ca</mml:mi></mml:mrow><mml:mrow><mml:mn>0.5</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">MnO</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn><

Millange, Franck; Brion, S. de; Chouteau, G.

doi:10.1103/physrevb.62.5619

Cited by 155 publications

(114 citation statements)

References 23 publications

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“…The charge ordering traps out mobile holes, so the magnitude of α(T) increases sharply on cooling through T CO , and a further increase on cooling through T N indicates a long-range T OO ≈T N in this material. Independent neutron-diffraction experiments 15 have revealed that short-range orbital ordering increases on cooling in the interval T N <T<T CO . The CO and short-range orbital order appear to introduce a frustration that suppresses long-range magnetic order, which is why long-range T OO ≈T N .…”

Section: Iii-results and Discussionmentioning

confidence: 99%

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Phase competition inL0.5A0.5MnO3perovskites

et al. 2002

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Single crystals of the systems Pr 0.5 (Ca 1-x Sr x ) 0.5 MnO 3 , (Pr 1-y Y y ) 0.5 (Ca 1-x Sr x ) 0.5 MnO 3 , and Sm 0.5 Sr 0.5 MnO 3 were grown to provide a series of samples with fixed ratio Mn(III)/Mn(IV)=1 having geometric tolerance factors that span the transition from localized to itinerant electronic behavior of the MnO 3 array. A unique ferromagnetic phase appears at the critical tolerance factor t c = 0.975 that separates charge ordering and localized-electron behavior for tt c . This ferromagnetic phase, which has to be distinguished from the ferromagnetic metallic phase stabilized at tolerance factors t>t c , separates two distinguishable Type-CE antiferromagnetic phases that are metamagnetic. Measurements of the transport properties under hydrostatic pressure were carried out on a compositions t a little below t c in order to compare the effects of chemical vs. hydrostatic pressure on the phases that compete with one another near t=t c .

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Section: Iii-results and Discussionmentioning

confidence: 99%

“…15. 1 The transition is first-order, and when phase segregation occurs at too low a temperature for atomic diffusion, it may be accomplished in a perovskite by cooperative oxide-ion displacements.…”

Section: I-introductionmentioning

confidence: 99%

Phase competition inL0.5A0.5MnO3perovskites

et al. 2002

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“…These bonds promote local crystal structure distortions, which is the reason why the local Jahn-Teller orbital ordering is preserved. Indeed, the temperature of the charge and orbital ordering in Bi 0.5 Sr 0.5 MnO 3 is unusually high, above 500 K [23,24], whereas the characteristic temperature of charge and orbital ordering in the structures R 0.5 Sr 0.5 MnO 3 is 150 K [25,26]. Due to the local static Jahn-Teller distortions, the anisotropic character of the exchange interactions between the manganese ions persist.…”

Section: Resultsmentioning

confidence: 99%

Magnetic phase transitions in the system La1−xBixMnO3+λ

Troyanchuk

Mantytskaja

Szymczak

et al. 2002

Low Temperature Physics

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The crystal structure and magnetic properties of the La1−xBixMnO3+λ system (0⩽x⩽1;λ⩽0.08) are studied as functions of the oxygen and bismuth contents. In oxidized samples La1−xBixMnO3+λ a phase transition from a ferromagnetic state (rhombohedric phase) to a state of the spin glass type (quasitetragonal phase) is observed with increase of the bismuth concentration. The reduced samples La1−xBixMnO3 are weak ferromagnets down to x⩽0.6 and then transform into a ferromagnetic state. It is supposed that the Bi3+ ions stabilize the dx2−y2 orbitals in the nearest Mn3+ ions whereas the dz2 orbitals of the La3+ ions are stabilized. The orbitally disordered phases and dx2−y2-orbitally ordered phases are ferromagnetic, the dz2-orbitally ordered phases show antiferromagnetic ordering, and the state of the orbital glass type corresponds to a state of the spin glass type.

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“…The lowest temperature phase seems to be either the CE phase, consisting of ferromagnetic zigzag chains with relative antiferromagnetic (AF) order (as in La 1/2 Ca 1/2 MnO 3 , where it was first proposed [2,3], and in Nd 1/2 Sr 1/2 MnO 3 [4] or Nd 1/2 Ca 1/2 MnO 3 [5]) or an A-type phase, i.e, ferromagnetic planes with relative AF alignment (as in Pr 1/2 Sr 1/2 MnO 3 [4]). The competition between the CE and A phases appears even in a simple one-orbital model [6] because of the interplay of ferromagnetic double-exchange and AF superexchange between the core t 2g spins of Mn (see also Fig.…”

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confidence: 99%

Doping and Field-Induced Insulator-Metal Transitions in Half-Doped Manganites

2005

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We argue that many properties of the half-doped manganites may be understood in terms of a new two-(eg electron)-fluid description, which is energetically favorable at intermediate Jahn-Teller (JT) coupling. This emerges from a competition between canting of the core spins of Mn promoting mobile carriers and polaronic trapping of carriers by JT defects, in the presence of CE, orbital and charge order. We show that this explains several features of the doping and magnetic field induced insulator-metal transitions, as the particle-hole asymmetry and the smallness of the transition fields."Half-doped" manganites such as Re 1−x A x MnO 3 with x = 1/2 where Re is a 3+ rare-earth ion and A a 2+ alkaline earth ion have been the object of extensive studies for many years [1] ). The competition between the CE and A phases appears even in a simple one-orbital model [6] because of the interplay of ferromagnetic double-exchange and AF superexchange between the core t 2g spins of Mn (see also Fig. 1). The presence of charge and orbital order as proposed by Goodenough [3] is more difficult to establish. X-ray diffraction experiments do suggest the presence of large Jahn-Teller (JT) distortions [4,7] with two inequivalent Mn sites. In the CE phase, the alternating (3x 2 − r 2 )/(3y 2 − r 2 ) orbital order (consistent with the observed distortions) was shown to optimize the anisotropic hopping energy of the e g electrons in a more realistic two e g orbital model [8]. The origin of charge-order was attributed to on-site [8] or intersite Coulomb interactions [9,10], though the latter tends to favor a Wigner crystal [9] rather than the charge stacked order found experimentally [1]. The role of the JT coupling has been investigated using imposed JT distortions [11] as well as by extensive classical Monte-Carlo simulations that lead to the observed charge stacked ordering [12].However, several fundamental issues remain to be understood. One of them is the striking asymmetry with respect to the addition of electrons or holes. Experimentally, added electrons typically favor ferromagnetic metallic phases while added holes favor insulating phases [1]. In contrast, band structure arguments [8], and treatments including JT distortions adiabatically and classically [12] lead to metallic phases on both sides. Another puzzling feature, first seen in (Nd,Sm) 1/2 Sr 1/2 MnO 3 [13] and later seen to be ubiquitous [1], is that magnetic-fields ∼ 10−40 Tesla, which are extremely small compared with Néel or charge ordering temperatures ∼ 200 K, induce an insulator-metal transition. This can be viewed as another manifestation of the colossal magneto-resistance (CMR) in doped manganites [1]. An explanation is that this arises from the proximity of the CE phase to a ferromagnetic phase [6,10,14]; but it is difficult to understand why the parameters in so many systems should all be so finely tuned as to be near the phase boundary.Recently, starting from a large JT coupling picture, a two-fluid e g electron model, one polaronic and localized, and the ...

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Charge, orbital, and magnetic order inNd0.5Ca0.5MnO3<

Cited by 155 publications

References 23 publications

Phase competition inL0.5A0.5MnO3perovskites

Phase competition inL0.5A0.5MnO3perovskites

Magnetic phase transitions in the system La1−xBixMnO3+λ

Doping and Field-Induced Insulator-Metal Transitions in Half-Doped Manganites

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