First neutron Bragg-edge imaging experimental results at CSNS

The neutron Bragg-edge imaging is expected to be a new non-destructive energy-resolved neutron imaging technique for quantitatively two-dimensional or three-dimensional visualizing crystallographic information in a bulk material,which could be benefited from pulsed neutron source.Here we build a Bragg-edge imaging system on the General Purpose Powder Diffractometer at the China Spallation Neutron Source.The residual strain mapping of a bent Q235 ferrite steel sample has been achieved with a spectral resolution of 0.15%by the time-of-flight neutron Bragg-edge imaging on this system.The results show its great potential applications in materials science and engineering.

Strong interlayer magnetic exchange coupling in La_(3)Ni_(2)O_(7-δ)revealed by inelastic neutron scattering

After several decades of studies of high-temperature superconductivity,there is no compelling theory for the mechanism yet;however,the spin fluctuations have been widely believed to play a crucial role in forming the superconducting Cooper pairs.The recent discovery of high-temperature superconductivity near 80 K in the bilayer nickelate La_(3)Ni_(2)O_(7)under pressure provides a new platform to elucidate the origins of high-temperature superconductivity.We perform elastic and inelastic neutron scattering studies on a polycrystalline sample of La_(3)Ni_(2)O_(7-δ)at ambient pressure.No magnetic order can be identified down to 10 K.The absence of long-range magnetic order in neutron diffraction measurements may be ascribed to the smallness of the magnetic moment.However,we observe a weak flat spin-fluctuation signal in the inelastic scattering spectra at~45 meV.The observed spin excitations could be interpreted as a result of strong interlayer and weak intralayer magnetic couplings for stripe-type antiferromagnetic orders.Our results provide crucial information on the spin dynamics and are thus important for understanding the superconductivity in La_(3)Ni_(2)O_(7).