講演情報
[14p-P01-10]Cation defect influence on the inelastic carrier scattering time in γ-Al2O3/SrTiO3 heterostructures
〇(D)JIWON YANG1, Mikk Lippmaa1 (1.ISSP, Univ. of Tokyo)
キーワード：
Oxide thin film、Heterostructure、Pulsed laser deposition
The γ-Al2O3/SrTiO3 heterostructure interface is known to form a high-mobility two-dimensional electron gas (2DEG) at low temperatures due to electron doping at the interface caused by oxygen vacancies. Interestingly, this heterostructure exhibits Rashba-type spin-orbit interaction (SOI) due to the interfacial electric field asymmetry between the substrate and the film. However, since the carriers at the interface are derived from oxygen vacancies, the 2DEG in this heterostructure simultaneously contains both high-mobility carriers and scattering centers, complicating the analysis of the transport properties and the intrinsic SOI strength.
Therefore, to isolate factors affecting the transport properties of the heterostructure, the cation defect density (VSr, VTi) was intentionally varied to systematically change the inelastic scattering time. Since the SOI originates from the asymmetry of the heterostructure, it should be independent of the cation defect density. Thus, the effect of cation defects on inelastic scattering can be investigated independently.
We employed pulsed laser deposition (PLD) to fabricate the heterostructures because the interface defect density in PLD-grown heterostructures is proportional to the re-sputtering damage caused by the ablation plume plasma. The plume damage generates both oxygen and cation defects, but the oxygen vacancy density can be independently controlled by mild oxygen annealing. Systematic change of the cation vacancy density is thus possible.
This presentation examines the effects of controlled cation defects on the inelastic scattering time through low-temperature magnetotransport measurements, including the analysis of the weak antilocalization (WAL) signature in magnetoconductance. The analysis revealed information on the SOI strength and the inelastic scattering time.
Therefore, to isolate factors affecting the transport properties of the heterostructure, the cation defect density (VSr, VTi) was intentionally varied to systematically change the inelastic scattering time. Since the SOI originates from the asymmetry of the heterostructure, it should be independent of the cation defect density. Thus, the effect of cation defects on inelastic scattering can be investigated independently.
We employed pulsed laser deposition (PLD) to fabricate the heterostructures because the interface defect density in PLD-grown heterostructures is proportional to the re-sputtering damage caused by the ablation plume plasma. The plume damage generates both oxygen and cation defects, but the oxygen vacancy density can be independently controlled by mild oxygen annealing. Systematic change of the cation vacancy density is thus possible.
This presentation examines the effects of controlled cation defects on the inelastic scattering time through low-temperature magnetotransport measurements, including the analysis of the weak antilocalization (WAL) signature in magnetoconductance. The analysis revealed information on the SOI strength and the inelastic scattering time.