Abstract
A detailed analysis of the hyperfine properties of the lighter group-II metals, beryllium and magnesium, has been carried out to understand the relation between the electronic structures of these hcp metals. The "lens" and "butterflies" of the magnesium Fermi surface have large character, leading to an appreciable value of the Knight shift . In contrast, beryllium does not have these pieces of the Fermi surface, and this qualitatively explains the vanishingly small for beryllium. Core polarization (cp) plays an important role in explaining the experimental values of . There is a basic difference between beryllium and magnesium as regards the cp contribution to the Knight shift (). For beryllium, , the part of the cp contribution is negative and this, together with a small direct contribution , leads to a vanishingly small value for (0.7×%), as compared to -0.25×% obtained experimentally. Orbital effects are expected to explain the remaining discrepancy in beryllium. For magnesium, is roughly 38% of , and the total theoretical value of is 0.0554%, compared to the experimental value of 0.112%. The uncertainties in the exchange enhancement of and the role of other contributions to are discussed. The relaxation time in beryllium is quite large because of the small spin density, and is found to be 1.0035× deg sec as compared to 1.66× obtained experimentally. No experimental value of is available for magnesium. Our theoretical value, including exchange enhancement effects, is 0.0346× deg sec. The relatively large contribution to in both the metals plays an important role in the deviation of from its ideal value, .
- Received 25 May 1969
DOI:https://doi.org/10.1103/PhysRevB.1.432
©1970 American Physical Society