Nodal quasiparticle in pseudogapped colossal magnetoresistive manganites

Mannella, Norman; Yang, Wanli; Zhou, X. J.; Zheng, Hong; Mitchell, J. F.; Zaanen, Jan; Devereaux, T. P.; Nagaosa, Naoto; Hussain, Zahid; Shen, Zhi‐Xun

doi:10.1038/nature04273

Cited by 255 publications

(245 citation statements)

References 31 publications

(46 reference statements)

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“…(6) The systematic measurement of the electronic band structure including the Fermi surfaces, which is crucial to understand the correlation effects on spin dynamics. Though progress in the study of the Fermi surface topology with high-resolution angle-resolved photoelectron spectroscopy (ARPES) has been made in the layered manganites such as La 1.2 Sr 1.8 Mn 2 O 7 [75,76], it is difficult to determine the electronic structure in these three-dimensional manganites because they cannot be cleaved to obtain a reasonably good surface. Surface effects [77,78] due to the surface lattice relaxation, segregation, and/or imperfection would affect the measured electronic structure by using surface sensitive techniques like ARPES.…”

Section: Discussionmentioning

confidence: 99%

Magnons in ferromagnetic metallic manganites

Zhang¹,

Ye²,

Sha³

et al. 2007

J. Phys.: Condens. Matter

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Ferromagnetic (FM) manganites, a group of likely half-metallic oxides, are of special interest not only because they are a testing ground for the classical double-exchange interaction mechanism for the 'colossal' magnetoresistance, but also because they exhibit an extraordinary arena of emergent phenomena. These emergent phenomena are related to the complexity associated with strong interplay between charge, spin, orbital, and lattice. In this review, we focus on the use of inelastic neutron scattering to study the spin dynamics, mainly the magnon excitations in this class of FM metallic materials. In particular, we discuss the unusual magnon softening and damping near the Brillouin zone boundary in relatively narrow-band compounds with strong Jahn-Teller lattice distortion and charge-orbital correlations. The anomalous behaviours of magnons in these compounds indicate the likelihood of cooperative excitations involving spin and lattice as well as orbital degrees of freedom.

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Section: Discussionmentioning

confidence: 99%

Magnons in ferromagnetic metallic manganites

Zhang¹,

Ye²,

Sha³

et al. 2007

J. Phys.: Condens. Matter

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“…As discussed in ref. 4, the x = 0.36, 0.38 compounds studied here do not contain the lowenergy pseudogap of the x = 0.4 samples [5][6][7][8] (see the Methods section for more details on this, the possible issue of surface sensitivity of ARPES and of possible intergrowths at the surface). The much larger metallic spectral weight of these nonpseudogapped compounds also allows us to study the electronic behaviour in greater detail.…”

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confidence: 99%

A local metallic state in globally insulating La1.24Sr1.76Mn2O7 well above the metal–insulator transition

et al. 2007

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The distinction between metals, semiconductors and insulators depends on the behaviour of the electrons nearest the Fermi level E F , which separates the occupied from the unoccupied electron energy levels. For a metal, E F lies in the middle of a band of electronic states, whereas E F in insulators and semiconductors lies in the gap between states. The temperatureinduced transition from a metallic to an insulating state in a solid is generally connected to a vanishing of the low-energy electronic excitations 1 . Here we show the first direct evidence of a counter-example, in which a significant electronic density of states at the Fermi energy exists in the insulating regime. In particular, angle-resolved photoemission data from the colossal magnetoresistive oxide La 1.24 Sr 1.76 Mn 2 O 7 show clear Fermi-edge steps, both below the metal-insulator transition temperature T C , when the sample is globally metallic, and above T C , when it is globally insulating. Further, small amounts of metallic spectral weight survive up to temperatures more than twice T C . Such behaviour may also have close ties to a variety of exotic phenomena in correlated electron systems, including the pseudogap temperature in underdoped cuprates 2 .As shown in Fig. 1a, the colossal magnetoresistive (CMR) oxide La 2−2x Sr 1+2x Mn 2 O 7 (x = 0.36,0.38) shows a metal-insulator transition at a T C just below 130 K, at which point the system also switches from being a ferromagnet (low temperature T) to a paramagnet (high T) 3 . We carried out angle-resolved photoemission spectroscopy (ARPES) experiments on cleaved single crystals of these materials, with an experimental arrangement as described elsewhere 4 . ARPES is an ideal experimental probe of the electronic structure because it gives the momentum-resolved single-particle excitation spectrum. As discussed in ref. 4, the x = 0.36, 0.38 compounds studied here do not contain the lowenergy pseudogap of the x = 0.4 samples 5-8 (see the Methods section for more details on this, the possible issue of surface sensitivity of ARPES and of possible intergrowths at the surface). The much larger metallic spectral weight of these nonpseudogapped compounds also allows us to study the electronic behaviour in greater detail. Although we find only minimal differences between the x = 0.36 and x = 0.38 compounds, all ARPES spectra shown here are from x = 0.38 samples. Figure 1b shows a large-energy-scale experimental picture of a low-temperature d x 2 −y 2 symmetry band taken along the blue cut near the zone boundary, as shown in the inset. We are able to get clean data by isolating the various bilayer-split bands using different photon energies, as described in ref. 4. In particular, in this paper we show only data from the antibonding bilayer-split band, which has Fermi crossings at k x = ±0.17π/a, k y = 0.9π/a, corresponding to the solid Fermi surface of the inset of Fig. 1b. The energy-distribution curves (EDCs) at the Fermi wavevector k F (indicated by the red line in Fig. 1b) taken at a series of temper...

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“…The FM state is a polaronic metal with a strong anisotropic character of the electronic excitations, strikingly similar to the pseudogap phases in heavily underdoped cuprate high-temperature superconductors such as Bi 2212. A strong mass enhancement and a small renormalization factor are found to account for the metallic properties [70,71]. The temperature dependence of resistivity in the metallic state is intimately related to polaronic metallic ground state and the insulator-to-metallic state can be attributed to the polaron coherence condensation process acting in concert with the double-exchange mechanism.…”

Section: Discussion and Analysis Of Resultsmentioning

confidence: 89%

Metallic and semi-conducting resistivity behaviour of La0.7Ca0.3−x K x MnO3 (x = 0.05, 0.1) manganites

Varshney

Dodiya

2014

J Theor Appl Phys

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The temperature dependence of electrical resistivity, q, of ceramic La 0.7 Ca 0.3-x K x MnO 3 (x = 0.05, 0.1) is investigated in metallic and semi-conducting phase. The metallic resistivity is attributed to be caused by electron-phonon, electron-electron and electron-magnon scattering. Substitutions affect average mass and ionic radii of A-site resulting in an increase in Debye temperature h D attributed to hardening of lattice with K doping. The optical phonon modes shift gradually to lower mode frequencies leading to phonon softening. Estimated resistivity compared with reported metallic resistivity, accordingly q diff. = [q exp. -{q 0 ? q e-ph (=q ac ? q op )}], infers electron-electron and electron-magnon dependence over most of the temperature range. Semi-conducting nature is discussed with variable range hopping and small polaron conduction model. The decrease in activation energies and increase in density of states at the Fermi level with enhanced Ca doping is consistently explained by cationic disorder and Mn valence.

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Nodal quasiparticle in pseudogapped colossal magnetoresistive manganites

Cited by 255 publications

References 31 publications

Magnons in ferromagnetic metallic manganites

Magnons in ferromagnetic metallic manganites

A local metallic state in globally insulating La1.24Sr1.76Mn2O7 well above the metal–insulator transition

Metallic and semi-conducting resistivity behaviour of La0.7Ca0.3−x K x MnO3 (x = 0.05, 0.1) manganites

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