Induced ferromagnetism in Mo-substituted<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mi>LaMnO</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:mrow></mml:math>

Lu, W. J.; Sun, Yan; Zhao, Bin; Zhu, Xiangde; Song, Wei

doi:10.1103/physrevb.73.174425

Cited by 36 publications

(38 citation statements)

References 24 publications

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“…Martensites are recognizable by morphology, as the transition proceeds preferably via strain-free interface planes. Although this type of transition is named after the steel alloy martensite, it has also been reported at the firstorder charge-ordering transition in manganites at much larger dopings (Podzorov et al 2001, Kolb et al 2004, Lu et al 2006. It may also apply to the current systems, as in both cases the transition involves the onset of long-range orbital ordering; this happens together with charge ordering in the higher doped systems.…”

Section: Discussionmentioning

confidence: 92%

Continuous first-order orbital order–disorder transition in Nd_1−xCa_xMnO₃

Colin¹,

Buurma²,

Zimmermann³

et al. 2008

J. Phys.: Condens. Matter

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Continuous first-order orbital order-disorder transition in Nd(1-x)Ca(x)MnO (3) Colin, C. V.; Buurma, A. J. C.; Von Zimmermann, M.; Palstra, T. T. M. Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. AbstractThe nature of the cooperative Jahn-Teller (JT) transition accompanied by orbital order-disorder in Nd 1−x Ca x MnO 3 has been studied by high temperature (300-1200 K) synchrotron and laboratory x-ray powder diffraction in the low doping region (0 x 0.1). For very low doping a large temperature range of phase coexistence associated with a first-order transition has been observed, resembling a martensitic transformation. The transition appears continuous because of a gradual evolution of the volume fractions of the phases over a broad temperature interval. The first-order nature of the transition and the phase coexistence is suppressed with increasing doping.

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Section: Discussionmentioning

confidence: 92%

Continuous first-order orbital order–disorder transition in Nd_1−xCa_xMnO₃

Colin¹,

Buurma²,

Zimmermann³

et al. 2008

J. Phys.: Condens. Matter

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“…It is known that e-h interactions play a crucial role in the optical response of semiconductors [36], especially, semiconducting nanostructures [37][38][39][40]. Excitonic effects in BBG with a finite bandgap are expected to be important, considering that the lowestenergy van Hove singularity in its joint electronic density of states exhibits a one-dimensional (1D), and not a twodimensional (2D), behavior (i. e. , it diverges as inverse of the energy difference from the bandgap) [32].Here, we obtain the optical response of a BBG including e-h interactions by solving the Bethe-Salpeter equation (BSE):where A S cvk is the amplitude of a free e-h pair configuration composed of the electron state |ck and the hole state |vk , Ω S is the exciton excitation energy, E ck and E vk are quasiparticle energies, and K eh is the e-h interaction kernel [36]. The absorption spectrum is calculated by evaluating the optical matrix elements [36] using the eigenstates and eigenvalues of the BSE.…”

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confidence: 99%

“…It is found that there are negligible many-electron effects on the low-energy (≤ 1 eV) optical response of graphene and bilayer graphene [30]. There have also been theoretical studies within a singleparticle picture on the electronic and optical properties of biased bilayer graphene (BBG) [32][33][34][35]. However, theoretical investigation of excitonic effects on the optical response of this novel tunable bandgap system has yet to be performed up to now.…”

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Tunable Excitons in Biased Bilayer Graphene

Park¹,

Louie²

2010

Nano Lett.

106

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Recent measurements have shown that a continuously tunable bandgap of up to 250 meV can be generated in biased bilayer graphene [Y. Zhang et al., Nature 459, 820 (2009)], opening up pathway for possible graphene-based nanoelectronic and nanophotonic devices operating at room temperature. Here, we show that the optical response of this system is dominated by bound excitons. The main feature of the optical absorbance spectrum is determined by a single symmetric peak arising from excitons, a profile that is markedly different from that of an interband transition picture. Under laboratory conditions, the binding energy of the excitons may be tuned with the external bias going from zero to several tens of meV's. These novel strong excitonic behaviors result from a peculiar, effective "one-dimensional" joint density of states and a continuously-tunable bandgap in biased bilayer graphene. Moreover, we show that the electronic structure (level degeneracy, optical selection rules, etc.) of the bound excitons in a biased bilayer graphene is markedly different from that of a two-dimensional hydrogen atom because of the pseudospin physics.The low-energy electronic states of graphene are described by a massless Dirac equation [1][2][3]. If an extra layer is added [ Fig. 1(a)], the electronic properties change drastically and the charge carriers become massive [ Fig . Indeed, a bandgap has been observed in the case of an internal perpendicular electric field generated by an imbalance of doped charge between the two graphene layers [16]. Also, bandgap opening in bilayer graphene under an electric field from a single gate has been observed by infra-red spectroscopy [17][18][19][20][21], quantum Hall measurement [22], and scanning tunneling spectroscopy [23].A bandgap opening up in bilayer graphene under an electric field from a double-gate configuration has further been observed in transport experiments [24,25] and quantum Hall measurements [26]. Very recently, infrared measurements showed that the bandgap of bilayer graphene in a double-gate geometry is continuously tunable up to 250 meV, an order of magnitude higher than the thermal energy at room temperature [27]. This discovery provides exciting new possibilities for the nanoelectronic and nanophotonic device applications of bilayer graphene at room temperature.Theoretical studies on the optical response of intrinsic bilayer graphene within a single-particle picture [28,29] as well as including electron-hole (e-h) interactions [30,31] have been performed. It is found that there are negligible many-electron effects on the low-energy (≤ 1 eV) optical response of graphene and bilayer graphene [30]. There have also been theoretical studies within a singleparticle picture on the electronic and optical properties of biased bilayer graphene (BBG) [32][33][34][35]. However, theoretical investigation of excitonic effects on the optical response of this novel tunable bandgap system has yet to be performed up to now. It is known that e-h interactions play a crucial role in the optical...

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“…etc., some Mn 3+ would convert into Mn 2+ , which leads to the Mn 2+ -Mn 3+ mixed valence in La 1−x A x MnO 3 (A=Ce 4+ , Te 4+ ...) [8,9] [10,11] , but LaMn 1−x B x O 3 , such as LaMn 1−xTi x O 3 [12] , LaMn 0.096 Mo 0.04 O 3 [13] , LaMn 0.096 Fe 0.04 O 3 [14] , etc., has no MIT, which are usually insulator at 0 T.…”

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confidence: 99%

Anomalous magnetotransport in LaMn1−x Te x O3

Tan

Chen

Zhang

2009

Sci. China Ser. G-Phys. Mech. Astron.

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The LaMn 1−x Te x O 3+δ (x=0.1, 0.2, 0.3) were synthesized using solid-state reaction method for the first time. X-ray photoemission spectrum (XPS) shows that in the samples the Te ions have a valence of Te 4+ , and Mn 3+ ions are partly converted into Mn 2+ and Mn 4+ due to the excess oxygen and Te doping. The magnetotransport associated with Mn 2+ , Mn 3+ and Mn 4+ was investigated. The experimental results show that the samples are insulator at 0 T when the amount of Mn 3+ is much larger or less than the sum of Mn 2+ and Mn 4+ ; by contrast, the samples display metal to insulator transition with increasing temperature when the amount of Mn 3+ is close to the sum of Mn 2+ and Mn 4+ . These anomalous magnetotransport behaviors were analyzed in the frame of the double-exchange (DE) mechanism.colossal magnetoresistance, La-Te-Mn-O, magnetotransport Doped LaMnO 3 have been widely studied due to a rich variety of physical properties [1][2][3][4] . The prominent one is the colossal magnetoresistance (CMR) effect, a phenomenon of the resistive transition induced by the magnetic transition, and CMR is traditionally explained by the double exchange (DE) [5] interaction. The key role in DE mechanism is played by Mn ions, the unique magnetic ions in LaMnO 3 , which affect not only the transport behaviors of manganites by the network of Mn-OMn, but also the magnetism of materials by the spin variation of Mn ions.As demonstrated by numerous studies, the valence of Mn ions in the manganites varies with the dopant, which is considered the intrinsic factor to understanding CMR effect. Mn ions are usually all trivalent (Mn 3+ ) in LaMnO 3 .When La ions were substituted partially by divalent ions, such as Ca 2+ , Sr 2+ etc., some Mn 3+ would convert into Mn 4+ , and Mn 3+ -Mn 4+ mixed valences are formed in the stable manganites of La 1−x A x MnO 3 [5][6][7][8] .When La ions were substituted partially by tetravalent ions, such as Ce 4+ , Te 4+ ... etc., some Mn 3+ would convert into Mn 2+ , which leads to the Mn 2+ -Mn 3+ mixed valence in La 1−x A x MnO 3 (A=Ce 4+ , Te 4+ ...) [8,9] . The interactions between Mn 4+ (or Mn 2+ ) ions and the neighboring Mn 3+ ions via O 2− are believed to contribute to the DE effect.The influence of the La-site substitution in manganites on DE mechanism is indirect, depending on the conversion of Mn 3+ ions. The direct influence, undoubtedly, is the Mn-site substitution. Recently, most studies on the Mn-site substitution focus on the La 1−x A x MnO 3 or LaMnO 3 . It is found that the manganites with the formula of La 1−x A x Mn 1−y O 3 (A=Ca 2+ , Sr 2+ ...; M=Zr 2+ , Cr 3+ , Ta 4+ ,...) or LaMn 1−x B x O 3 (B=T 4+ , Mo 6+ ...) still remain Mn 3+ -Mn 4+ (or Mn 3+ -Mn 2+ ) mixed-valence, and undergo ferro-to para-magnetism (FM-PM) transition. However, both have the different magnetotransport behavior.

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Induced ferromagnetism in Mo-substitutedLaMnO3

Cited by 36 publications

References 24 publications

Continuous first-order orbital order–disorder transition in Nd_1−xCa_xMnO₃

Continuous first-order orbital order–disorder transition in Nd_1−xCa_xMnO₃

Tunable Excitons in Biased Bilayer Graphene

Anomalous magnetotransport in LaMn1−x Te x O3

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Induced ferromagnetism in Mo-substitutedLaMnO3

Cited by 36 publications

References 24 publications

Continuous first-order orbital order–disorder transition in Nd1−xCaxMnO3

Continuous first-order orbital order–disorder transition in Nd1−xCaxMnO3

Tunable Excitons in Biased Bilayer Graphene

Anomalous magnetotransport in LaMn1−x Te x O3

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Continuous first-order orbital order–disorder transition in Nd_1−xCa_xMnO₃

Continuous first-order orbital order–disorder transition in Nd_1−xCa_xMnO₃