Neutron Scattering with a Triple-Axis Spectrometer

Shirane, G.; Shapiro, S. M.; Tranquada, J. M.

doi:10.1017/cbo9780511534881

Cited by 332 publications

(305 citation statements)

References 0 publications

Supporting

Mentioning

294

Contrasting

Order By: Relevance

“…To rule out spurious peaks as a source for the phonon localization feature, the spectral features were confirmed with measurements at equivalent points in reciprocal space. Spurious features, or spurions, may occur in triple-axis inelastic neutron scattering measurements due to higher order reflections from the monochromator or analyser, incoherent scattering from the monochromator or analyser and scattering from materials in the beam other than the crystal 41 . This type of scattering usually produces features in limited regions of reciprocal space, but in rare cases can produce streaks that mimic dispersion.…”

Section: Methodsmentioning

confidence: 99%

Phonon localization drives polar nanoregions in a relaxor ferroelectric

et al. 2014

View full text Add to dashboard Cite

Relaxor ferroelectrics exemplify a class of functional materials where interplay between disorder and phase instability results in inhomogeneous nanoregions. Although known for about 30 years, there is no definitive explanation for polar nanoregions (PNRs). Here we show that ferroelectric phonon localization drives PNRs in relaxor ferroelectric PMN-30%PT using neutron scattering. At the frequency of a preexisting resonance mode, nanoregions of standing ferroelectric phonons develop with a coherence length equal to one wavelength and the PNR size. Anderson localization of ferroelectric phonons by resonance modes explains our observations and, with nonlinear slowing, the PNRs and relaxor properties. Phonon localization at additional resonances near the zone edges explains competing antiferroelectric distortions known to occur at the zone edges. Our results indicate the size and shape of PNRs that are not dictated by complex structural details, as commonly assumed, but by phonon resonance wave vectors. This discovery could guide the design of next generation relaxor ferroelectrics.

show abstract

Section: Methodsmentioning

confidence: 99%

Phonon localization drives polar nanoregions in a relaxor ferroelectric

et al. 2014

View full text Add to dashboard Cite

show abstract

“…The neutron magnetic scattering cross-section 21 can be conveniently factored into the product of the dynamical spin-correlation function, S(Q,E), which is determined by the cooperative behaviour of electronic spins described by the Hubbard, t -J or Heisenberg model, and the square of the magnetic form factor, |F (Q)| 2 . F (Q) is the Fourier transform of the electronic magnetization cloud associated with each spin, that is, its Wannier wavefunction, and includes the covalency effects.…”

mentioning

confidence: 99%

Effect of covalent bonding on magnetism and the missing neutron intensity in copper oxide compounds

et al. 2009

View full text Add to dashboard Cite

Theories involving highly energetic spin fluctuations are among the leading contenders for explaining high-temperature superconductivity in the cuprates 1 . These theories could be tested by inelastic neutron scattering (INS), as a change in the magnetic scattering intensity that marks the entry into the superconducting state provides a precise quantitative measure of the spin-interaction energy involved in the superconductivity 2-11 . However, the absolute intensities of spin fluctuations measured in neutron scattering experiments vary widely, and are usually much smaller than expected from fundamental sum rules, resulting in 'missing' INS intensity 2-5,12,13 . Here, we solve this problem by studying magnetic excitations in the one-dimensional related compound, Sr 2 CuO 3 , for which an exact theory of the dynamical spin response has recently been developed. In this case, the missing INS intensity can be unambiguously identified and associated with the strongly covalent nature of magnetic orbitals. We find that whereas the energies of spin excitations in Sr 2 CuO 3 are well described by the nearestneighbour spin-1/2 Heisenberg Hamiltonian, the corresponding magnetic INS intensities are modified markedly by the strong 2p-3d hybridization of Cu and O states. Hence, the ionic picture of magnetism, where spins reside on the atomic-like 3d orbitals of Cu 2+ ions, fails markedly in the cuprates.Over the past 20 years, the magnetic properties of cuprates have been studied extensively by theorists and experimentalists alike. These systems are usually described within the antiferromagnetic Mott insulator model, in which the unpaired electrons are localized on the Cu 2+ ions because of the overwhelming cost in the on-site Coulomb interaction energy, U , associated with the charge transfer between the Cu sites, a strong correlation phenomenon. Virtual electron hopping, which in the one-band Hubbard model of a Mott insulator often adopted for cuprates 14 is quantified by the transition matrix element, t , results in antiferromagnetic exchange. For t U , electronic spins form the only low-energy electronic degrees of freedom. Their properties are well approximated by the spin-1/2 Heisenberg Hamiltonian on the lattice 15 , H = J i(nn)j S i S j , with the nearest-neighbour exchange coupling J ≈ 4t 2 /U . This description conveniently splits the problem of electronic magnetism in the Mott insulator into two parts 15 . The first deals with the electron transfer between the neighbouring sites of the crystal lattice, which is determined by the overlap integral (∼t ) of the wavefunctions occupied by the unpaired electrons, and leads to the Hubbard model, or the Heisenberg spin Hamiltonian. The second concerns the form of the electronic Wannier wavefunctions, that is, the shape of the spin magnetization cloud associated with 1 ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX, UK, 2 Department of Physics, University College London, Gower Street, London WC1E 6BT, UK, 3 London Centre for Nanotechnology, 17-19 Go...

show abstract

“…We now turn to the description of spectrometers dedicated to inelastic neutron scattering experiments [2][3][4][5][6][7][8][9][10]. As for diffraction, most of those experiments demand a monochromatic beam, to be prepared from the white beam produced by the neutron source (reactor or pulsed source).…”

Section: Principlesmentioning

confidence: 99%

“…The second method is by Bragg scattering from a single crystal, known as triple-axis spectroscopy (TAS) [8,10,11]:…”

Section: Principlesmentioning

confidence: 99%

Inelastic neutron scattering

Petit

2017

EPJ Web Conf.

View full text Add to dashboard Cite

Abstract. The goal of the JDN22 school was to propose a progressive teaching eager to improve the expertise of students in neutron diffraction. Neutron-based techniques have indeed proved for decades to be essential tools in the investigation of condensed matter. This lecture is however concerned with inelastic neutron scattering and is thus somehow apart. In the context of this school, it should then only be considered as a brief introduction. We give simple examples along with the basics of the spectrometers, and finally useful formula for the inelastic cross sections in different situations. We strongly encourage interested readers to refer to the bibliography for more detailed information.

show abstract

Neutron Scattering with a Triple-Axis Spectrometer

Cited by 332 publications

References 0 publications

Phonon localization drives polar nanoregions in a relaxor ferroelectric

Phonon localization drives polar nanoregions in a relaxor ferroelectric

Effect of covalent bonding on magnetism and the missing neutron intensity in copper oxide compounds

Inelastic neutron scattering

Contact Info

Product

Resources

About