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Tejsner and Jean-Claude Grivel and W. Schmidt and R. Toft-Petersen and P. Steffens and M. Wells and L. Udby and K. Lefmann and A. View PDF on arXiv. Save to Library. Create Alert. Launch Research Feed. Share This Paper. Figures and Tables from this paper. Figures and Tables. References Publications referenced by this paper. Glassy low-energy spin fluctuations and anisotropy gap in La 1.

Research Feed. Probing the connections between superconductivity, stripe order, and structure in La1. Rotated stripe order and its competition with superconductivity in La1. Charge density wave fluctuations in La2-x Srx CuO4 and their competition with superconductivity.

Evidence for unusual superconducting correlations coexisting with stripe order in La 1. Spin dynamics and exchange interactions in CuO measured by neutron scattering. Related Papers.

By clicking accept or continuing to use the site, you agree to the terms outlined in our Privacy PolicyTerms of Serviceand Dataset License.The magnetic correlations within the cuprates have undergone intense scrutiny as part of efforts to understand high-temperature superconductivity.

Magnetic excitations along this direction are found to be systematically softened and broadened with doping, at a higher rate than the excitations along the antinodal direction. This phenomenology is discussed in terms of the nature of the magnetism in the doped cuprates. As a result, survival of the high-energy magnetic excitations, even in the overdoped regime, indicates that these excitations are marginal to pairing, while the influence of the low-energy excitations remains ambiguous.

Works referenced in this record:. GOV collections:. Abstract The magnetic correlations within the cuprates have undergone intense scrutiny as part of efforts to understand high-temperature superconductivity.

Authors: Meyers, D. Meyers, D. Doping dependence of the magnetic excitations in La2-xSrxCuO4. United States: N. Copy to clipboard. United States. Free Publicly Available Full Text. Accepted Manuscript Publisher. Accepted Manuscript DOE.

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This enables us to measure the magnetic excitations in this highly hole-doped incommensurate regime and compare our results with those found in the low-doped incommensurate regime that exhibit hourglass magnetic spectra. The hourglass shape of magnetic excitations completely disappears given a high Sr doping. Moreover, broad low-energy excitations are found, which are not centered at the incommensurate magnetic peak positions but around the quarter-integer values that are typically exhibited by excitations in the checkerboard charge ordered phase.

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The recent observation of an hourglass magnetic spectrum in single-layer perovskite cobaltates 1 has attracted substantial attention because it resembles the hourglass-shaped excitation spectra that are universally observed in high-temperature superconducting HTSC cuprates 2345678910 This implies that a Fermi surface is not necessary in order for an hourglass spectrum to occur. In other words, this suggests a connection between hourglass spectra and charge stripe phases. However, Y. Drees et al.

For completeness, we would like to remark that in an earlier study, the small deviations from commensurate magnetism in La 1. In order to determine which interactions are essential for the emergence of hourglass magnetic spectra, a study of cobaltates above half-doping instead of below 15161718is necessary. Thus, we were able to measure the previously unknown spin excitations of highly hole-doped cobaltates and to observe the differences between the low and high-doping regimes, which consequently allowed us to identify the strong exchange interactions in the undoped regimes as the fundamental elements of the presence of the high-energy portion of the hourglass spectra.

This value exceeds the nominal value of 0. Our magnetic phase diagram, which is shown in Fig. The dotted lines follow the magnetic peak positions and act as guide to the eyes. The solid lines are fitted to the data. Sr-concentrations x and the measurement temperature are indicated. Transition temperatures are the onset-temperatures based on the temperature-dependent neutron measurements of the elastic neutron scattering intensities shown in the inset.

We studied the charge correlations in La 1. At even higher hole-doping the situation starts to change. In Fig. A weak structural signal, which is indicated by an arrow in Fig.Thank you for visiting nature. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser or turn off compatibility mode in Internet Explorer.

In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript. Antiferromagnetic correlations have been argued to be the cause of the d -wave superconductivity and the pseudogap phenomena exhibited by the cuprates. Despite the apparent ubiquity of the hourglass dispersion, the differences between the spectra for LSCO and YBCO have motivated ostensibly contradictory microscopic interpretations: incommensurate spin-density-wave SDW fluctuations of local moments unidirectional charge-spin stripe order is one example 4or a spin-exciton because of particle—hole excitations in the SC state 25.

Although it has long been known that AF correlations may cause the d -wave superconductivity exhibited by the cuprates 9such theoretical approaches were not thought to be able to account for the PG phenomenology. These developments raise the prospect that much of the cuprate phase diagram may be understood as driven by AF correlations. Such measurements might also help illuminate the relevance of the seemingly universal hourglass response.

The slight suppression of T c at this doping level might be a signature of a competing ground state, and it is interesting to determine if this has an effect on the dynamic magnetic susceptibility. As shown in Fig. This establishes the commensurate excitations as a signature of the PG state.

The blue region represents the PG regime. The shaded orange region in c represents the excess scattering below T c because of the resonance mode.

Vertical error bars in a — c are statistical errors 1 s. The magnetic nature of the response is confirmed through spin-polarized neutron scattering and also from its Q dependence, which follows the magnetic form factor see Supplementary Notes 4 and Supplementary Fig.

Phase transitions and spin excitations in new multiferroics with modulated magnetic structure

Error bars represent statistical error 1 s. The white circles in c — g represent the momentum resolution at the corresponding energy transfers. We fit constant- Q data such as those in Fig. Solid lines: guides to the eye. The same binning is used at higher temperatures.Analysis based on a two-component picture of high-quality data clarified the possible coexistence of upright standing incommensurate IC excitations with gapless commensurate C excitations in the energy-momentum space.

The analysis results imply that the superposition of two components with a particular intensity balance forms an hourglass-shaped excitation in appearance. Spin dynamics in doped lamellar cuprate oxide is a fundamental issue in solid-state physics. However, owing to the insufficient experimental resolution and the intensity of the neutron beam in earlier measurements, it was difficult to determine adequate models from the observed fuzzy spectra.

The typical size of the crystal was 8 mm in diameter and 40 mm in length. Five single crystals were co-aligned with a total mosaic of less than 1. The statistical accuracy of intensity was increased with the statistical error of the signal ratio from 0. We shifted the spectra obtained in the previous measurements downward for a clear comparison. Moreover, we successfully obtained high-quality data in this study. Figure 1.

Nature of the magnetic stripes in fully oxygenated La$_{2}$CuO$_{4+y}$

The spectra were compared with those previously obtained ones by our measurement to show the improvement in data quality. The horizontal bars represent the momentum resolution. In Figs. In the spectrum along this direction, the phonon intensity can be eliminated; therefore, the detailed structure of the magnetic signal can be investigated. The horizontal bars in the figure represent the momentum resolution. This thermal evolution of the excitation spectra was observed in La 1.

Figure 2. The thick lines represent the fitting result. The horizontal bars correspond to the momentum resolution. The solid lines in Figs. Figures 3 a — 3 g show the detailed energy dependence of the spectrum near the energies at 5 K. Furthermore, from Fig. In Fig. Figure 3.Here, we report the decomposition of La 2—x Sr x CuO 4 into La 2 O 3 and Cu nanoparticles in ultrahigh vacuum, observed by in situ heating experiments in a transmission electron microscope.

Two major resultant solid phases are identified as metallic Cu and La 2 O 3 by electron diffraction, simulation, and electron energy-loss spectroscopy EELS analyses. With the aid of calculations, La 2 O 3 phases are further identified to be derivatives of a fluorite structure—fluorite, pyrochlore, and distorted bixbyite—characterized by different oxygen-vacancy order.

Additionally, the bulk plasmon energy and the fine structures of the O K and LaM 4,5 EELS edges are reported for these structures, along with simulated O K x-ray absorption near-edge structure. The resultant Cu nanoparticles and La 2 O 3 phases remain unchanged after cooling to room temperature. Works referenced in this record:.

GOV collections:. Title: Decomposition of L a 2 — x S r x Cu O 4 into several L a 2 O 3 phases at elevated temperatures in ultrahigh vacuum inside a transmission electron microscope.

Abstract Here, we report the decomposition of La 2—x Sr x CuO 4 into La 2 O 3 and Cu nanoparticles in ultrahigh vacuum, observed by in situ heating experiments in a transmission electron microscope. Decomposition of La2—xSrxCuO4 into several La2O3 phases at elevated temperatures in ultrahigh vacuum inside a transmission electron microscope.

United States: N. Copy to clipboard. United States. Two major resultant solid phases are identified as metallic Cu and La2O3 by electron diffraction, simulation, and electron energy-loss spectroscopy EELS analyses. With the aid of calculations, La2O3 phases are further identified to be derivatives of a fluorite structure—fluorite, pyrochlore, and distorted bixbyite—characterized by different oxygen-vacancy order.

Additionally, the bulk plasmon energy and the fine structures of the O K and LaM4,5 EELS edges are reported for these structures, along with simulated O K x-ray absorption near-edge structure. The resultant Cu nanoparticles and La2O3 phases remain unchanged after cooling to room temperature.

Free Publicly Available Full Text. Accepted Manuscript Publisher.

new structures in the magnetic excitations of la2

Accepted Manuscript DOE. Copyright Statement. Other availability.

new structures in the magnetic excitations of la2

Search WorldCat to find libraries that may hold this journal. The inset to a is a corresponding SAED pattern. All figures and tables 4 total. LinkedIn Pinterest Tumblr.Thank you for visiting nature.

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You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser or turn off compatibility mode in Internet Explorer. In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript. Antiferromagnetism is relevant to high-temperature high- T c superconductivity because copper oxide and iron arsenide superconductors arise from electron- or hole-doping of their antiferromagnetic parent compounds 123456.

There has been contradictory evidence regarding the microscopic origin of the antiferromagnetic order in iron arsenide materials 56with some favouring a localized picture 1112131415 and others supporting an itinerant point of view 16171819 More importantly, there has not even been agreement about the simplest effective ground-state Hamiltonian necessary to describe the antiferromagnetic order 21222324 We find that the spin waves in the entire Brillouin zone can be described by an effective three-dimensional local-moment Heisenberg Hamiltonian, but the large in-plane anisotropy cannot.

Therefore, magnetism in the parent compounds of iron arsenide superconductors is neither purely local nor purely itinerant, rather it is a complicated mix of the two.

new structures in the magnetic excitations of la2

Since the discovery of static antiferromagnetic order with a spin structure as in Fig. A determination of the effective magnetic exchange coupling and ground-state Hamiltonian in the parent compounds of these materials is important because such an understanding will provide the basis against which superconductivity-induced changes can be identified.

If the static long-range antiferromagnetic order shown in Fig.

new structures in the magnetic excitations of la2

Furthermore, spin-wave excitations should exhibit longitudinal and transverse polarization, and damp into single-particle excitations Stoner continuum through the transfer of an electron spin from the majority to the minority band at high energies as shown schematically in Fig.

On the other hand, if magnetic order in iron pnictides has a local moment origin as in the parent compounds of the copper oxides 1one should observe well-defined essentially instrumental resolution limited spin waves throughout the Brillouin zone and magnetic coupling between local moments should be dominated by direct and super-exchange interactions Fig.

In recent neutron scattering experiments, the presence of itinerant magnetic excitations and a Stoner continuum have been suggested in BaFe 2 As 2 ref. Furthermore, the authors find that a Heisenberg Hamiltonian with effective in-plane nearest-neighbours Fig. Although these results are interesting, they are similar to earlier work 21222324 and have not determined the effective ground-state Hamiltonian because the signs of the effective change coupling constants Fig.

A correct determination of all exchange coupling constants J 1aJ 1b and so on is important because it enables the formation of an appropriate ground-state Hamiltonian from which superconductivity can be derived.

We co-aligned 6. To quantitatively determine the spin-wave dispersion, we cut through the two-dimensional images similar to Fig. In spite of the spin-wave intensity modulation along the L -direction due to the exchange interaction J c between the FeAs planes 23 Fig. As spin waves become less dispersive as the zone boundary is approached, we locate the spin-wave excitations through energy scans at a fixed wave vector.

The solid lines are model fits to the data after convoluting the cross-section to the instrumental resolution. Typical instrumental resolutions are shown as dotted lines in a and d. Error bars indicate one sigma.

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The error bars indicate one sigma.


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