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Zaanen, Jan; Littlewood, P. B.

doi:10.1103/physrevb.50.7222

Cited by 172 publications

(157 citation statements)

References 32 publications

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“…In the former case, sliding of the charge stripes is prevented by the presence of the intervening spin stripes. The fact that the magnetically ordered Ni sites have S ¼ 1, rather than S ¼ 1 2 in cuprates, helps to localize the charge stripes 39,40 . When the charge stripes start to move, the spin fluctuations become strongly damped 21,22,24 .…”

Section: Discussionmentioning

confidence: 99%

“…Using a model appropriate for cuprates, Kaneshita et al 42 calculated charge collective modes that disperse steeply from the charge-order wave vector and leave detectable anomalies when they cross (and mix with) phonon branches, however, there was no prediction of a low-energy lattice response independent of the phonon modes. Presumably, one must account for the strong electron-lattice coupling in nickelates 39 . The possible connection between the low-energy stripe fluctuations and the anomaly in a bond-stretching phonon branch 43 and other possible phonon anomalies requires further exploration.…”

Section: Discussionmentioning

confidence: 99%

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Direct observation of dynamic charge stripes in La2–xSrxNiO4

Anissimova

Parshall

et al. 2014

Nat Commun

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The insulator-to-metal transition continues to be a challenging subject, especially when electronic correlations are strong. In layered compounds, such as La 2-x Sr x NiO 4 and La 2-x Ba x CuO 4 , the doped charge carriers can segregate into periodically spaced charge stripes separating narrow domains of antiferromagnetic order. Although there have been theoretical proposals of dynamically fluctuating stripes, direct spectroscopic evidence of charge-stripe fluctuations has been lacking. Here we report the detection of critical lattice fluctuations, driven by charge-stripe correlations, in La 2-x Sr x NiO 4 using inelastic neutron scattering. This scattering is detected at large momentum transfers where the magnetic form factor suppresses the spin fluctuation signal. The lattice fluctuations associated with the dynamic charge stripes are narrow in q and broad in energy. They are strongest near the charge-stripe melting temperature. Our results open the way towards the quantitative theory of dynamic stripes and for directly detecting dynamical charge stripes in other strongly correlated systems, including high-temperature superconductors such as La 2-x Sr x CuO 4 .

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Direct observation of dynamic charge stripes in La2–xSrxNiO4

Anissimova

Parshall

et al. 2014

Nat Commun

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“…8 Such a behavior of ǫ indicates a fixed hole density of one hole per Ni ion in a DW, and is consistent with the HF predictions both in the single and in multiband models. 19,20,21,22,23,60,61,62 Finally, a fixed hole density along the DWs results in the pinning of the chemical potential µ for x ≤ 1/3, whereas a large (≃ 1 eV/hole) downward shift appears in the higher doping regime. 46 It is interesting to establish whether the above results concerning the stripe phases in the ground state and their variation under increasing doping appear solely in the realistic e g model, or they are generic and remain also a common feature of the DDH model with only diagonal hopping elements given by Eq.…”

Section: Ground State Energiesmentioning

confidence: 99%

“…In contrast, the HF approximation used here allows one to describe charge and spin modulation with larger unit cells and hence it should provide an answer to the important question whether the description of NiO 2 planes by the simplified effective e g model described below yields results consistent with the predictions of the CT model. 60,61,62 An important aspect of these studies, qualitatively different from the pioneering work on the cuprates where the relevant models yield DWs with nonmagnetic Cu 3+ ions, 19,20,21,22,23 is that DWs in the nickelates are formed of Ni 3+ ions carrying a finite spin S = 1/2 leading to a FM polarization around them.…”

mentioning

confidence: 99%

“…The stripes were also obtained in the theory using either the HF approximation applied to a multiband CT model, in which both the nickel and oxygen degrees of freedom are explicitely taken into account, 60,61,62 or by the ED of finite clusters within the effective two-band model (1) extended by the coupling of e g electrons to the lattice. 63 However, due to a large number of basis states, the latter calculation has solely been done for an eight site cluster allowing only for investigating stripe phases with a small unit cell observed experimentally at high doping levels x = 1/3 and x = 1/2.…”

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confidence: 99%

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Microscopic origin of diagonal stripe phases in doped nickelates

2006

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We investigate the electron density distribution and the stability of stripe phases in the realistic two-band model with hopping elements between eg orbitals at Ni sites on the square lattice, and compare these results with those obtained for the doubly degenerate Hubbard model with two equivalent orbitals and diagonal hopping. For both models we determine the stability regions of filled and half-filled stripe phases for increasing hole doping x = 2 − n in the range of x < 0.4, using Hartree-Fock approximation for large clusters. In the parameter range relevant to the nickelates, we obtain the most stable diagonal stripe structures with filling of nearly one hole per atom, as observed experimentally. In contrast, for the doubly degenerate Hubbard model the most stable stripes are somewhat reminiscent of the cuprates, with half-filled atoms at the domain wall sites. This difference elucidates the crucial role of the off-diagonal eg hopping terms for the stripe formation in La2−xSrxNiO4. The influence of crystal field is discussed as well. I. STRIPE PHASES IN NICKELATESStripe phases are one of the most exciting phenomena of modern condensed matter physics. They have been observed in a variety of systems, including nickelates, 1,2,3,4,5,6,7,8 cuprates, 9,10,11,12,13,14,15 and manganites. 16,17,18 Among them, layered La 2−x Sr x CuO 4 (LSCO), La 2−x−y Nd y Sr x CuO 4 (Nd-LSCO), La 2−x Sr x NiO 4 (LSNO), and La 2 NiO 4+δ (LNO) compounds play plausibly the most prominent role. However the similarity between them is superficial only, and the stripes in the cuprates differ from the stripes in the nickelates in many respects. For instance, they are dynamical in the former, and static in the latter. In addition, in Nd-LSCO 9,10,11,12,13,14 and LSCO, 15 one finds the so-called half-filled stripes, with the density of one doped hole per two atoms along the domain wall (DW). In contrast, it is clear from a variety of experiments that magnetic states within doped NiO 2 planes of the nickelates are filled stripes with density of one doped hole per one atom in a DW. 1,2,3,4,5,6,7,8 The question of filling is not the only difference between the nickelate and cuprate stripes, however. Neutron diffraction measurements performed on Nd-LSCO revealed that magnetic peaks are displaced from the antiferromagnetic (AF) maximum at Q AF = π(1, 1) to the points Q s = π(1 ± 2ǫ, 1) and Q s = π(1, 1 ± 2ǫ) and the shift ǫ depends linearly on hole doping x for x < 1/8, while it is almost constant at higher doping. These values correspond to a superposition of vertical (01) and horizontal (10) DWs. The essentially identical modulation and doping dependence of ǫ was observed in superconducting crystals of LSCO with x > 0.05. Conversely, experiments on LSNO established that spin order is characterized by the wave vectors Q s = π(1 ± ǫ, 1 ± ǫ) with ǫ ≃ x for x < 1/3, corresponding to a constant charge of one hole/Ni ion along a diagonal DW, in agreement with the predictions made in the pioneering works by Zaanen and Gunnarsson 19 and others, 20,21,...

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Vibronic Structural Instability on Doping-Dependent Bands

Kristoffel¹

1998

phys. stat. sol. (b)

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Supposing the presence of a doping-induced narrow band besides the valence band, the vibronic dynamic instability caused by interaction of these bands is analysed having in mind the description of the recently observed d 0X05 structural transformation in YBa 2 Cu 3 O 7Àd .Various structural events on bulk, mesoscopic and local scales are known in high-T c superconductors. Distinct doping treatments are necessary to reach high T c values, which influence also the structural properties. The charge carriers (holes) created by doping lead to the formation of polaron-type clusters with phase separation [1,2,3,4,5]. A striped structure of the superconductivity play-ground CuO 2 planes has been found [4,5,6,7,8]. Distorted material (LTT structure) stripes of mesoscopic size intercalate undistorted (LTO) bulk bearing itinerant carriers. In the distorted region the plane Cu (2) is shifted towards the apex O(4) ion. These structural data support the two-component scenario of the high-T c superconductivity [9,10,11,12] incorporating itinerant and localized (polaron) type carriers. Such approaches are developing in various realizations at present and take account of changes in the electron spectrum due to the doping. At favourable for the high T c compositions the actual part of the electronic spectrum seems to consist of a wide valence hole band and an outpushed narrow band created through hole capture and lattice distortion [9,12,13,14]. Interband pair-scattering superconductivity [15] in such a two-band model has been considered in [16].The presence of two sufficiently close electron bands opens a structural instability channel through their vibronic mixing [17] (like a band-pseudo-Jahn-Teller-effect). Such a scheme has been used to describe the T-O displacive structural transition in La 2Àx Sr xCuO 4 [18]. Recently a displacive structural transformation in the CuO 2 planes of YBa 2 -Cu 3 O 7Àd at d 0X05 and T 25 K has been found [19]. It consists in dominant and anomalously large displacement of the Cu(2) ion off the O(2, 3) layer. This d value corresponds to the under-overdoped phase separation line. One can expect that under such conditions the polaron-like narrow induced band has a ripe development. The structural transition under consideration has seemingly relations to doping-induced stripening of the CuO 2 plane, phase separation and modification of the electronic spectrum.We try to associate the d 0X05 transition with the vibronic interaction between the wide-valence (predominantly O2p) and hole-induced narrow band. The energy zero is taken at the bottom of the wide band

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Freezing electronic correlations by polaronic instabilities in dopedLa2NiO4

Cited by 172 publications

References 32 publications

Direct observation of dynamic charge stripes in La2–xSrxNiO4

Direct observation of dynamic charge stripes in La2–xSrxNiO4

Microscopic origin of diagonal stripe phases in doped nickelates

Vibronic Structural Instability on Doping-Dependent Bands

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