THE LOW-TEMPERATURE HYPERFINE-STRUCTURE OF QUARTZ UNDER UNIAXIAL PRESSURE

The uniaxial pressure dependence of the muonium hyperfine tensor was m easured at 80 K. Uniaxial pressures (0 and 0.2 GPa) were applied along the a-axis of quartz, and the hyperfine tensor was measured by applyi ng various transverse fields between 0 and 7 G. The structure appears to be the result of the three chemically equivalent sites in quartz. W hen pressure is applied perpendicular to the crystallographic c-axis o f quartz, the symmetry of these sites is broken such that two chemical ly inequivalent sites are observed. The resulting hyperfine structure is discussed and qualitative explanations are proposed.