Manganese-doped intrinsic semiconductors offer tremendous promise for developing and advancing traditional electronic and spin-based electronic devices. These technologies rely on imparting dynamic control over the intrinsic charge carriers that transfer information within the electronic pathways. One potential strategy to achieve this level of control is through the modulation of specific electronic ground states of Mn and the other transition-metal dopants. In this talk, we discuss our recent work that focuses on revealing dopant-defect interactions of redox-active Mn centers in two particularly favorable semiconductor materials, SrTiO3 and the layered Ruddelsden-Popper, Sr2TiO4 bulk powders. The ground state electronic structure of the Mn dopants was monitored via multifrequency and variable-temperature electron paramagnetic resonance (EPR) spectroscopy and analyzed using the appropriate Spin-Hamiltonian parameters and EasySpin computer simulation/fitting software. We demonstrate that a mild chemical reduction can reduce substitutional Mn4+ dopants by two electrons to Mn2+ and create Ti3+ defects. A brief but comprehensive analysis of the two hosts will be presented vis-à-vis the incorporation of Mn ions, the differences in the intrinsic and dopant-induced defects, and the structural variations that facilitate (or hinder) these charge-compensation mechanisms. Additional spectroscopic evidence of the dopants and defect states will be presented to support our findings from EPR spectroscopy.

Spectroscopic Examination of the Tunable Valency of Mn Dopants in Strontium Titanate-based Powders

ACS Spring Meeting 2021

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