We report the behavior of low energy 8 Li + implanted into gold as revealed by beta-detected NMR. At an external magnetic field of 3 T, two narrow resonances are observed, which are attributed to Li in the octahedral interstitial and the substitutional lattice sites. The Knight shifts for these two resonances are found to be temperature independent with values of +141͑4͒ and +73͑5͒ ppm, respectively. The spin-lattice relaxation rate in high magnetic fields at 290 K is slow, consistent with the Korringa relation; however, the rate increases dramatically for magnetic fields below about 2 mT. We attribute this to interaction of the 8 Li spin with the host lattice nuclear spins.
A β-detected nuclear quadrupole resonance (NQR) spectrometer becomes a powerful tool to study changes in nuclear ground-state properties along isotopic chains when coupled to a laser excitation beamline to polarize the nuclei of interest. Recently, the β-NQR technique in a zero magnetic field has been applied for the first time to measure the ratio of static nuclear quadrupole moments of 8,9 Li, Q 9 /Q 8 = 0.966 75(9) denoted by Q 8 for 8 Li and Q 9 for 9 Li, respectively. This shows agreement with present literature values but with significantly improved precision. Based on the literature, the quadrupole moment for 8 Li has been re-evaluated to be |Q 8 | = 32.6(5) mb. From this, the quadrupole moment for 9 Li is calculated as |Q 9 | = 31.5(5) mb with the error being dominated by the error of Q 8 .
Thin film reactions of Cu/Al multilayer films were investigated by differential scanning calorimetry and transmission electron microscopy. Sequential intermetallic compound formation was found in the temperature range from 300 to 620 K. With excess copper present in the as-deposited trilayer and multilayer films, the observed sequence was CuAl2 and Cu9Al4, and the interfacial reactions were controlled by interfacial and grain boundary diffusion. The activation energies for the formation of CuAl2 and Cu9Al4 are 0.78±0.11 and 0.83±0.2 eV, respectively.
Non-Hermitian physics has recently attracted much attention in optics and photonics. Less explored is non-Hermitian magnonics that provides opportunities to take advantage of the inevitable dissipation of magnons or spin waves in magnetic systems. Here we demonstrate non-Hermitian coherent coupling of two distant nanomagnets by fast spin waves with sub-50 nm wavelengths. Magnons in two nanomagnets are unidirectionally phase-locked with phase shifts controlled by magnon spin torque and spin-wave propagation. Our results are attractive for analog neuromorphic computing that requires unidirectional information transmission.
The temperature dependence of the frequency shift and spin-lattice relaxation rate of isolated, nonmagnetic (8)Li impurities implanted in a nearly ferromagnetic host (Pd) are measured by means of beta-detected nuclear magnetic resonance (beta-NMR). The shift is negative, very large, and increases monotonically with decreasing T in proportion to the bulk susceptibility of Pd for T > T* approximately 100 K. Below T*, an additional shift occurs which we attribute to the response of Pd to the defect. The relaxation rate is much slower than expected for the large shift and is linear with T below T*, showing no sign of additional relaxation mechanisms associated with the defect.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.