TE125 MOSSBAUER EFFECT IN PARAMAGNETIC AND ANTIFERROMAGNETIC MNTE2

The Mössbauer effect associated with the 35.6-keV (3212) transition in Te125 is applied to extract the electronic structure and the induced magnetic features of the ditelluride ligand in antiferromagnetic MnTe2 (TN=83.8°K). Measurements above TN at 90.1°K, reveal a quadrupole split spectrum with |e2qQ|=15.5 mm/sec. Absorption spectra obtained below TN result from a combination of a magnetic dipole interaction and a predominant electric quadrupole interaction with negative e2qQ. At 4.2°K (TTN=0.05) and 20.3°K (TTN=0.24) the internal magnetic field H=1147 kOe and the angle formed with qzz is 30°-5+3. At 77.3°K (TTN=0.925), H=553 kOe, and 0°<10°. The sign and magnitude of the quadrupole coupling constant as well as the observed anisotropy in the recoilless fraction are consistent with the molecular" conception of the Te1 - Te1- anion. Comparison of H in (Te125)1- and H in substituted (I129)1- (obtained from a separate experiment) suggests a transferred hyperfine interaction mechanism involving the unpairing of the ligand 5s orbitals. The resulting angle was found to be inconsistent with the suggested model of the spin arrangement as deduced from a neutron-diffraction pattern in powder samples by other authors. © 1969 The American Physical Society."