In115andTe125Nuclear Magnetic Resonance in the High-Pressure Metallic Phase of InTe

Abstract

The ${\mathrm{In}}^{115}$ and ${\mathrm{Te}}^{125}$ nuclear magnetic resonances have been observed in the cubic, metallic polymorph of InTe. Both resonances exhibit paramagnetic Knight shifts and have derivative linewidths which are more than an order of magnitude larger than predicted from either Van Vleck dipolar broadening or spin-lattice relaxation-time broadening. The Knight shifts of the indium resonance at 4.2, 77, and 300\ifmmode^\circ\else\textdegree\fi{}K are 2.52, 2.65, and 2.79%, respectively, while the corresponding values for the tellurium resonance are 0.185, 0.194, and 0.221%. The linewidths of both resonances increase with a decrease in temperature and at 4.2\ifmmode^\circ\else\textdegree\fi{}K the ${\mathrm{Te}}^{125}$ resonance has a derivative linewidth of 29.6 G. The ${\mathrm{In}}^{115}$ resonance shows evidence of electric quadrupole and Knight-shift broadening due to local deviations from cubic symmetry; however, an extrapolated residual linewidth of 57 G exists at 4.2\ifmmode^\circ\else\textdegree\fi{}K. Using calculated second moments with lattice sums over like and unlike nearest neighbors, the tellurium-resonance linewidth is seen to arise from both pseudodipolar and isotropic indirect exchange interactions with indium nuclei. The linewidth of the indium resonance contains a large contribution from the In-In psuedodipolar interaction, although exchange narrowing due to isotropic indirect exchange between like nuclei produces a Lorentzian lineshape. A model which is consistent with the observed Knight shifts and linewidths is proposed for the electronic structure of the metallic phase of InTe.