Ferroelectric domain reversal by electric field poling of lithium niobate crystals (LiNbO3) with varying stoichiometry and magnesium (MgO) doping level obtained from various commercial suppliers is investigated. Magnesium doping lowers the domain-wall velocity, increases the uniformity of the growth of the domains, and reduces the impact of crystal symmetry on the shape of the domains. Illumination with ultraviolet (UV) laser light (305nm) reduces the coercive field by up to 34% in MgO-doped crystals, but is accompanied by a degradation of poling quality. UV light of longer wavelengths (334nm) has no influence on the coercive field except for the MgO:LiNbO3 material of one supplier, where the field is reduced by 27%. In this case the poling quality is excellent. UV-induced reduction of stress-induced birefringence is observed in some samples. The results are of crucial relevance for light-induced domain engineering of LiNbO3 crystals.

This article describes the development and testing of the first automatically microfabricated probes to be used in conjunction with the magic angle coil spinning (MACS) NMR technique. NMR spectroscopy is a versatile technique for a large range of applications, but its intrinsically low sensitivity poses significant difficulties in analyzing mass- and volume-limited samples. The combination of microfabrication technology and MACS addresses several well-known NMR issues in a concerted manner for the first time: (i) reproducible wafer-scale fabrication of the first-in-kind on-chip LC microresonator for inductive coupling of the NMR signal and reliable exploitation of MACS capabilities; (ii) improving the sensitivity and the spectral resolution by simultaneous spinning the detection microcoil together with the sample at the “magic angle” of 54.74° with respect to the direction of the magnetic field (magic angle spinning – MAS), accompanied by the wireless signal transmission between the microcoil and the primary circuit of the NMR spectrometer; (iii) given the high spinning rates (tens of kHz) involved in the MAS methodology, the microfabricated inserts exhibit a clear kinematic advantage over their previously demonstrated counterparts due to the inherent capability to produce small radius cylindrical geometries, thus tremendously reducing the mechanical stress and tearing forces on the sample. In order to demonstrate the versatility of the microfabrication technology, we have designed MACS probes for various Larmor frequencies (194, 500 and 700 MHz) testing several samples such as water, Drosophila pupae, adamantane solid and LiCl at different magic angle spinning speeds.