title: Spin injection and detection in lanthanum- and niobium-doped SrTiO3 using the Hanle technique.
abstract: There has been much interest in the injection and detection of spin-polarized carriers in semiconductors for the purposes of developing novel spintronic devices. Here we report the electrical injection and detection of spin-polarized carriers into Nb-doped strontium titanate single crystals and La-doped strontium titanate epitaxial thin films using MgO tunnel barriers and the three-terminal Hanle technique. Spin lifetimes of up to ~100 ps are measured at room temperature and vary little as the temperature is decreased to low temperatures. However, the mobility of the strontium titanate has a strong temperature dependence. This behaviour and the carrier doping dependence of the spin lifetime suggest that the spin lifetime is limited by spin-dependent scattering at the MgO/strontium titanate interfaces, perhaps related to the formation of doping induced Ti(3+). Our results reveal a severe limitation of the three-terminal Hanle technique for measuring spin lifetimes within the interior of the subject material.
authors.affiliation: IBM Almaden Research Center, San Jose, California 95120, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Han
authors.forename: Xin
authors.initials: X
authors.lastname: Jiang
authors.forename: Adam
authors.initials: A
authors.lastname: Kajdos
authors.forename: See-Hun
authors.initials: SH
authors.lastname: Yang
authors.forename: Susanne
authors.initials: S
authors.lastname: Stemmer
authors.forename: Stuart S P
authors.initials: SS
authors.lastname: Parkin