Pure nuclear quadrupole resonance determination of the electric field gradient asymmetry for broad lines (and application to YBa2Cu3O7)

TL;DR

This paper introduces ADNQR, a novel angle-dependent nuclear quadrupole resonance technique for measuring the electric field gradient asymmetry in broad-line systems, demonstrated on YBa2Cu3O7 superconductors.

Contribution

The paper presents a new ADNQR method capable of determining eta in broad-line systems where existing spectroscopic methods fail, especially useful for inhomogeneous samples.

Findings

ADNQR successfully measures eta in broad-line systems.

The method is effective for single crystals and oriented powders.

Application to YBa2Cu3O7 demonstrates practical utility.

Abstract

We present an angle dependent nuclear quadrupole resonance (ADNQR) method to determine the electric field gradient asymmetry parameter eta in systems where the resonance line is so broad that the radio frequency field can excite only a portion of the nuclear spins. In this situation the recently developed spectroscopic methods are not applicable. ADNQR is useful for single crystals and oriented powders, and, for small eta determines eta^4. Therefore, it can be used to evaluate fluctuations in eta due to inhomogeneities. We demonstrate the application of ADNQR experimentally to oriented superconducting YBa2Cu3O7 powder.