Chemical shift of NMR in HgTe, CdTe and their alloys

Abstract

The chemical shifts of nuclear magnetic resonance in Hg_1-xCd_xTe alloys have been measured for the three nuclei at various compositions. A calculation of the band structure allows one to predict the observed shifts in the pure compounds HgTe and CdTe. In alloys the band structure is no longer a useful tool since the shifts are related to the local electronic structure. The shifts of mercury, cadmium and tellurium behave very differently as a function of cadmium content: mercury shift changes strongly, cadmium shift is weakly affected while the tellurium shift is practically constant. It is shown that the variation of the mercury shift occurs when second neighbours of mercury are substituted by cadmium atoms. On the other hand, the tellurium atoms are already surrounded by p-electrons; as the number of these electrons does not change, there is only an anisotropic chemical shift of tellurium.