Cobalt-doping effects in single crystalline and polycrystalline EuFe2−x Co x As2 compounds

Chen, Xiaobo; Ren, Zhi-An; Ding, Hongsheng; Liu, Lihua

doi:10.1007/s11433-010-4005-2

Cited by 33 publications

(65 citation statements)

References 25 publications

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“…This similarity suggests that lattice structural effects, rather than the effects of electronic doping, play a fundamental role in tuning the phase diagram in these substitutional studies [35]. However, more detailed investigations are required since other works addressing the substitution of Fe by Co reported that a transition to a superconducting state is realized in a much broader interval of Co substitution [12,36].…”

Section: Resultsmentioning

confidence: 88%

Field dependence of the Eu²⁺spin relaxation in EuFe_2−xCo_xAs₂

et al. 2012

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The layered compound EuFe 2 As 2 is an interesting model system to investigate the effects of well-defined local Eu 2+ 4f states on the itinerant electronic and magnetic properties of the FeAs layers. To address this subject, we investigated the series EuFe 2−x Co x As 2 (0.1 x 0.75) by electron spin resonance (ESR) of Eu 2+ to probe the spin dynamics of the itinerant subsystem. We relate the results to dc-susceptibility measurements and band structure calculations. As a consequence of the weak coupling between the local and itinerant subsystems, we found that the spin relaxation is well understood in terms of the exchange coupling among the local Eu 2+ spins. A pronounced field dependence of the Eu 2+ spin relaxation demonstrates the direct influence of magnetic fluctuations at the Fe 2−x Co x As 2 layers. Contents

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Section: Resultsmentioning

confidence: 88%

Field dependence of the Eu²⁺spin relaxation in EuFe_2−xCo_xAs₂

et al. 2012

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“…Extensions of the most standard model of inflation (Starobinskiǐ 1979;Guth 1981;Linde 1982) can produce substantial deviations from a Gaussian distribution of primordial density and potential fluctuations (see Bartolo et al 2004;Chen 2010;Desjacques & Seljak 2010 for recent reviews). The amount and shape of this deviation depend critically on the kind of non-standard inflationary model that one has in mind, as will be detailed later on.…”

Section: N O N -G Au S S I a N C O S M O L O G I E Smentioning

confidence: 99%

The clustering of galaxies and galaxy clusters: constraints on primordial non-Gaussianity from future wide-field surveys

Fedeli

Carbone

Moscardini

et al. 2011

Monthly Notices of the Royal Astronomical Society

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We investigate the constraints on primordial non‐Gaussianity with varied bispectrum shapes that can be derived from the power spectrum of galaxies and clusters of galaxies detected in future wide field optical/near‐infrared surveys. Having in mind the proposed ESA space mission Euclid as a specific example, we combine the spatial distribution of spectroscopically selected galaxies with that of weak lensing selected clusters. We use the physically motivated halo model in order to represent the correlation function of arbitrary tracers of the large‐scale structure in the Universe. As naively expected, we find that galaxies are much more effective in jointly constrain the level of primordial non‐Gaussianity fNL and the amplitude of the matter power spectrum σ8 than clusters of galaxies, due to the much lower abundance of the latter that is not adequately compensated by the larger effect on the power spectrum. Nevertheless, combination of the galaxy power spectrum with the cluster–galaxy cross‐spectrum can decrease the error on the determination of fNL by up to a factor of ∼2. This decrement is particularly evident for the less studied non‐Gaussian bispectrum shapes, the so‐called enfolded and the orthogonal ones. Setting constraints on these models can shed new light on various aspects of the physics of the early Universe, and hence it is of extreme importance. By combining the power spectra of clusters and galaxies with the cluster–galaxy cross‐spectrum we find constraints on primordial non‐Gaussianity of the order ΔfNL∼ a few, competitive and possibly superior to future cosmic microwave background experiments.

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“…The simplest possible model for the primordial fluctuations consists of a Gaussian random field with a nearly scaleinvariant power spectrum (Bardeen et al 1986). However, many models exist for the inflationary phase (Lyth & Liddle 2009), many of which would alter the statistics of the fluctuations, in particular introducing a non-Gaussian component (Chen 2010). It is therefore important to put observational constraints on the presence (and, once detected, on the amount) of primordial non-Gaussianity (PNG), in order to distinguish between models of the early universe.…”

Section: Introductionmentioning

confidence: 99%

Constraining primordial non-Gaussianity with future galaxy surveys

Giannantonio¹,

Porciani²,

Carron³

et al. 2012

Monthly Notices of the Royal Astronomical Society

172

246

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We study the constraining power on primordial non-Gaussianity of future surveys of the large-scale structure of the Universe for both near-term surveys (such as the Dark Energy Survey - DES) as well as longer term projects such as Euclid and WFIRST. Specifically we perform a Fisher matrix analysis forecast for such surveys, using DES-like and Euclid-like configurations as examples, and take account of any expected photometric and spectroscopic data. We focus on two-point statistics and we consider three observables: the 3D galaxy power spectrum in redshift space, the angular galaxy power spectrum, and the projected weak-lensing shear power spectrum. We study the effects of adding a few extra parameters to the basic LCDM set. We include the two standard parameters to model the current value for the dark energy equation of state and its time derivative, w_0, w_a, and we account for the possibility of primordial non-Gaussianity of the local, equilateral and orthogonal types, of parameter fNL and, optionally, of spectral index n_fNL. We present forecasted constraints on these parameters using the different observational probes. We show that accounting for models that include primordial non-Gaussianity does not degrade the constraint on the standard LCDM set nor on the dark-energy equation of state. By combining the weak lensing data and the information on projected galaxy clustering, consistently including all two-point functions and their covariance, we find forecasted marginalised errors sigma (fNL) ~ 3, sigma (n_fNL) ~ 0.12 from a Euclid-like survey for the local shape of primordial non-Gaussianity, while the orthogonal and equilateral constraints are weakened for the galaxy clustering case, due to the weaker scale-dependence of the bias. In the lensing case, the constraints remain instead similar in all configurations.Comment: 20 pages, 10 Figures. Minor modifications; accepted by MNRA

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Cobalt-doping effects in single crystalline and polycrystalline EuFe2−x Co x As2 compounds

Cited by 33 publications

References 25 publications

Field dependence of the Eu²⁺spin relaxation in EuFe_2−xCo_xAs₂

Field dependence of the Eu²⁺spin relaxation in EuFe_2−xCo_xAs₂

The clustering of galaxies and galaxy clusters: constraints on primordial non-Gaussianity from future wide-field surveys

Constraining primordial non-Gaussianity with future galaxy surveys

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Cobalt-doping effects in single crystalline and polycrystalline EuFe2−x Co x As2 compounds

Cited by 33 publications

References 25 publications

Field dependence of the Eu2+spin relaxation in EuFe2−xCoxAs2

Field dependence of the Eu2+spin relaxation in EuFe2−xCoxAs2

The clustering of galaxies and galaxy clusters: constraints on primordial non-Gaussianity from future wide-field surveys

Constraining primordial non-Gaussianity with future galaxy surveys

Contact Info

Product

Resources

About

Field dependence of the Eu²⁺spin relaxation in EuFe_2−xCo_xAs₂

Field dependence of the Eu²⁺spin relaxation in EuFe_2−xCo_xAs₂