Gd-doped BaSnO3: A transparent conducting oxide with localized magnetic moments

We have synthesized transparent, conducting, paramagnetic stannate thin films via rare-earth doping of BaSnO3. Gd3+ (4f7) substitution on the Ba2+ site results in optical transparency in the visible regime, low resistivities, and high electron mobilities, along with a significant magnetic moment. Pulsed laser deposition was used to stabilize epitaxial Ba0.96Gd0.04SnO3 thin films on (001) SrTiO3 substrates, and compared with Ba0.96La0.04SnO3 and undoped BaSnO3 thin films. Gd as well as La doping schemes result in electron mobilities at room temperature that exceed those of conventional complex oxides, with values as high as 60 cm2/V·s (n = 2.5 × 1020cm-3) and 30 cm2/V·s (n = 1 × 1020cm-3) for La and Gd doping, respectively. The resistivity shows little temperature dependence across a broad temperature range, indicating that in both types of films the transport is not dominated by phonon scattering. Gd-doped BaSnO3 films have a strong magnetic moment of ∼7 μB/Gd ion. Such an optically transparent conductor with localized magnetic moments may unlock opportunities for multifunctional devices in the design of next-generation displays and photovoltaics

Structure and magnetism of Fe-doped BaSnO3 thin films

BaSnO is an excellent candidate system for developing a new class of perovskite-based dilute magnetic semiconductors. In this study, we show that BaSn Fe O can be grown from a background pressure of ∼2×10 mTorr to oxygen pressures of 300 mTorr with high crystallinity and excellent structural quality. When grown in vacuum, the films may be weakly ferromagnetic with a nonzero x-ray magnetic circular dichroism signal on the Fe L edge. Growth with oxygen flow appears to suppress magnetic ordering. Even for very thick films grown in 100 mTorr O , the films are paramagnetic. The existence of ferromagnetism in vacuum-grown BaSnO may be attributed to the F-center exchange mechanism, which relies on the presence of oxygen vacancies to facilitate the ferromagnetism. However, other possible extrinsic contributions to the magnetic ordering, such as clusters of Fe O and FeO or contamination can also explain the observed behavior. 3 0.95 0.05 3 3 2 3 3 4 −

Reversible control of magnetism in La0.67Sr0.33MnO3 through chemically-induced oxygen migration

We demonstrate reversible control of magnetization and anisotropy in La Sr MnO films through interfacial oxygen migration. Gd metal capping layers deposited onto La Sr MnO leach oxygen from the film through a solid-state redox reaction to form porous Gd O . X-ray absorption and polarized neutron reflectometry measurements show Mn valence alterations consistent with high oxygen vacancy concentrations, resulting in suppressed magnetization and increased coercive fields. Effects of the oxygen migration are observed both at the interface and also throughout the majority of a 40 nm thick film, suggesting extensive diffusion of oxygen vacancies. After Gd-capped La Sr MnO is exposed to atmospheric oxygen for a prolonged period of time, oxygen diffuses through the Gd O layer and the magnetization of the La Sr MnO returns to the uncapped value. These findings showcase perovskite heterostructures as ideal candidates for developing functional interfaces through chemically-induced oxygen migration. 0.67 0.33 3 0.67 0.33 3 2 3 0.67 0.33 3 2 3 0.67 0.33

Magnetism and transport in transparent high-mobility BaSnO3 films doped with La, Pr, Nd, and Gd

We have explored the effect of magnetic rare-earth dopants substitutionally incorporated on the Ba sites of BaSnO3 in terms of electronic transport, magnetism, and optical properties. We show that for Ba0.92R0.08SnO3 thin films (where R=La,Pr,Nd,Gd), there is a linear increase of mobility with carrier concentration across all doping schemes. La-doped films have the highest mobilities, followed by Pr- and Nd-doped films. Gd-doped samples have the largest ionic size mismatch with the Ba site and correspondingly the lowest carrier concentrations and electron mobilities. However, crystallinity does not appear to be a strong predictor of transport phenomena; our results suggest that point defects more than grain boundaries are key ingredients in tuning the conduction of BaSnO3 films grown by pulsed laser deposition. Pronounced, nonhysteretic x-ray magnetic dichroism signals are observed for Pr-, Nd-, and Gd-doped samples, indicating paramagnetism. Finally, we probe the optical constants for each of the BaSnO3 doping schemes and note that there is little change in the transmittance across all samples. Together these results shed light on conduction mechanisms in BaSnO3 doped with rare-earth cations

Magnetism and transport in transparent high-mobility BaSnO3 films doped with La, Pr, Nd, and Gd

We have explored the effect of magnetic rare-earth dopants substitutionally incorporated on the Ba sites of BaSnO3 in terms of electronic transport, magnetism, and optical properties. We show that for Ba0.92R0.08SnO3 thin films (where R=La,Pr,Nd,Gd), there is a linear increase of mobility with carrier concentration across all doping schemes. La-doped films have the highest mobilities, followed by Pr- and Nd-doped films. Gd-doped samples have the largest ionic size mismatch with the Ba site and correspondingly the lowest carrier concentrations and electron mobilities. However, crystallinity does not appear to be a strong predictor of transport phenomena; our results suggest that point defects more than grain boundaries are key ingredients in tuning the conduction of BaSnO3 films grown by pulsed laser deposition. Pronounced, nonhysteretic x-ray magnetic dichroism signals are observed for Pr-, Nd-, and Gd-doped samples, indicating paramagnetism. Finally, we probe the optical constants for each of the BaSnO3 doping schemes and note that there is little change in the transmittance across all samples. Together these results shed light on conduction mechanisms in BaSnO3 doped with rare-earth cations.</p