Pure nuclear quadrupole resonance determination of the electric field gradient asymmetry for broad lines

Levy, Shahar; Keren, Amit

doi:10.1016/j.jmr.2004.01.005

Cited by 8 publications

(7 citation statements)

References 9 publications

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“…The maximum intensity is observed at the H 1 с orientation and decreases to zero at H 1 ||с. An analogous dependence was observed by us earlier for InSe [7] as well as by others authors in other compounds with layered crystal structure [8]. This confirms the anisotropy of the crystal structure and the existence of axial symmetry of the electric-field gradient in the local surroundings for Ga and In nuclei in GaSe and InSe compounds, respectively.…”

Section: Methodssupporting

confidence: 90%

Fine structure of NQR spectra in GaSe

Kovalyuk¹

2009

Semicond. phys. quantum electron. optoelectron.

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Peculiarities of the observation of nuclear quadrupole resonance (NQR) in GaSe crystals grown from melt are under investigations. The splitting of a resonance NQR line by two identical spectra is caused by the availability of non-equivalent positions of Ga atoms in the polytypes ,  and, probably, . The appearance of a fine structure in NQR spectra is related to ordering in the system of the lattice defects (polytypes), when the atomic Se-Ga-Ga-Se layers are stacked during the crystal growth.

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Section: Methodssupporting

confidence: 90%

Fine structure of NQR spectra in GaSe

Kovalyuk¹

2009

Semicond. phys. quantum electron. optoelectron.

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“…Our objective in this work is to determine η as a function of doping in different environments using ADNQR, which is described in detail elsewhere [11]. In this modification of standard NQR one measures the echo intensity in a coil, whose symmetry axis is in the direction r = (sin θ cos φ, sin θ sin φ, cos θ) with respect to the principal axis of the EFG, as a function of θ and ϕ.…”

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confidence: 99%

Charge-inhomogeneity doping relations inYBa2Cu3Oydetected by angle-dependent nuclear quadrupole resonance

et al. 2006

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The origin of charge inhomogeneity in YBa2Cu3Oy is investigated using a new experimental method designed to determine the nuclear quadrupole resonance (NQR) asymmetry parameter η for very wide NQR lines at different positions on the line. The method is based on the measurement of the echo intensity as a function of the angle between the radio frequency field H1 and the principal axis of the electric field gradient. Static charge inhomogeneity deduced from η > 0 are found in this compound, but only in conjunction with oxygen deficiency. This limits considerably the possible forms of charge inhomogeneity in bulk YBa2Cu3Oy.The discussion on the mechanism for high temperature superconductivity (HTSC) is focused these days on the presence or absence of charge and spin inhomogeneity in the CuO 2 planes. Such inhomogeneity can lead to a one dimensional boundary, possibly in the form of stripes, between "hole-rich" and "hole-poor" regions and, allegedly, to superconductivity.[1] Indeed, it is now established by both surface and bulk techniques that most of the underdoped cuprates phase separate into "hole-rich" and "hole-poor" regions. [LSCO] where the evidence for phase separation is derived from experiments sensitive to both magnetic fluctuation, such as muon spin relaxation (µSR) [3], and charge fluctuations such as nuclear quadrupole resonance (NQR).[4] Even in very underdoped YBa 2 Cu 3 O y (YBCO y ) phase separation is observed; neutron scattering from phonons related to charge inhomogeneity is found in doping levels up to YBCO 6.35 [5], and µSR detects a spin glass phase for a similar doping range. [6] However, the origin of this phase separation is still not clear; is it coming from competing phases in the CuO 2 plane, or does it simply stem from the quenched disorder introduced by doping?A possible way to address this question is to apply NQR to YBCO y since in this compound one can distinguish between different in-plane coppers [Cu(2)] resonance lines, and associate each line with a local environment. However, a standard NQR based determination of charge homogeneity is not available to date due to the complicated and very wide spectrum of underdoped YBCO (which will be reviewed below). The purpose of this work is to overcome the NQR problems and to shed light on the evolution of charge homogeneity in the bulk of YBCO close to optimal doping. For this purpose we developed a new experimental technique based on the measurement of the Cu(2) NQR echo intensity as a function of the angle between the radio frequency (RF) field, H 1 , and the principal axis of the electric field gradient (EFG) at the copper site. We call this angle-dependent NQR technique ADNQR. Standard NQR is based on the fact that nuclei with spin I > 1/2 can be viewed as positively charged oval objects. As a result, their energy inside a solid depends on their orientation in the electrostatic potential V (r) generated by the other nuclear and electronic charges. When the nuclear poles are close to positive charges their energy is high, and when th...

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“…Using the NQR method, the dependence of the spectrum intensity on the orientation of the crystallographic axes of an anisotropic crystal with respect to the vector of the magnetic component of the high-frequency field is investigated [12]. In fact, the two-dimensional crystal structure of monoselenide compounds makes it possible by the NQR method to orient the crystal along the selected coordinate system and, moreover, to reveal the features associated with the violation of the crystal symmetry, that is, structural defects.…”

Section: Research On 115 In Nqr Spectramentioning

confidence: 99%

The Use of Marginal Oscillator Detector with Increased Conversion Linearity for Recording Broadband Multiplet Nuclear Quadrupole Resonance Spectra

Samila¹

2021

J. Nano- Electron. Phys.

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Pure nuclear quadrupole resonance determination of the electric field gradient asymmetry for broad lines

Cited by 8 publications

References 9 publications

Fine structure of NQR spectra in GaSe

Fine structure of NQR spectra in GaSe

Charge-inhomogeneity doping relations inYBa2Cu3Oydetected by angle-dependent nuclear quadrupole resonance

The Use of Marginal Oscillator Detector with Increased Conversion Linearity for Recording Broadband Multiplet Nuclear Quadrupole Resonance Spectra

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