Work

Increased static dielectric constant in ZnMnO and ZnCoO thin films with bound magnetic polarons

Year: 2020

Type: article

Abstract: A novel small signal equivalent circuit model is proposed in the inversion regime of metal/( ZnO , ZnMnO , and ZnCoO ) semiconductor/ Si 3 N 4 insulator/p-Si semiconductor (MSIS) structures to describe the distinctive nonlinear frequency dependent capacitance ( C-F ) and conductance ( G-F ) behaviour in the frequency range from 50 Hz to 1 MHz. We modelled the fully depleted ZnO thin films to extract the static dielectric constant ( ε r ) of ZnO , ZnMnO , and ZnCoO . The extracted enhancement of static dielectric constant in magnetic n-type conducting ZnCoO ( ε r ≥ 13.0) and ZnMnO ( ε r ≥ 25.8) in comparison to unmagnetic ZnO ( ε r = 8.3–9.3) is related to the electrical polarizability of donor-type bound magnetic polarons ( BMP ) in the several hundred GHz range (120 GHz for CdMnTe ). The formation of donor-BMP is enabled in n-type conducting, magnetic ZnO by the s-d exchange interaction between the electron spin of positively charged oxygen vacancies $${V}_{o}^{+}$$ V o + in the BMP center and the electron spins of substitutional Mn 2+ and Co 2+ ions in ZnMnO and ZnCoO , respectively. The BMP radius scales with the Bohr radius which is proportional to the static dielectric constant. Here we show how BMP overlap can be realized in magnetic n-ZnO by increasing its static dielectric constant and guide researchers in the field of transparent spintronics towards ferromagnetism in magnetic, n-ZnO .

Source: Scientific Reports

DOI: 10.1038/s41598-020-63195-1