POLARIZATION EFFECTS ON MAGNETIC RESONANCES IN FERROELECTRIC POTASSIUM TANTALATE.
MASSACHUSETTS INST OF TECH CAMBRIDGE RESEARCH LAB OF ELECTRONICS
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Electric field effects on electron paramagnetic resonances EPR associated with Fe3 impurity ions in the perovskite ferroelectric KTaO3 are presented and discussed. A large effect D 0.003cm for E 14 kvcm was predicted and observed at 4.2 degrees K. The EPR angular dependence data for the Fe3 ion in a cubic environment are interpreted in terms of appropriate spin Hamiltonian parameters. The result is alpha 34510 x 0.0001cm and g 1.99 0.01. We also reported EPR spectra for Fe3 ions that have a neighboring oxygen vacancy, and also for Fe5, Mn, and Cr. Evidence for covalent bonding of magnetic impurities to the KTaO3 lattice is given. Optical absorption spectra associated with Fe, Mn, and Co impurities are also reported. A brief investigation was made of transport properties of slightly reduced, electrically conducting n-type samples of KTaO3. There is a strong temperature-dependent Hall mobility 28 sq cmvolt sec at room temperature and at least 63,000 sq cmvolt sec at 4.2K. A method for growing fairly large about 1 cu cm and good quality single crystals of KTaO3 is described.