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Abstract Exchange bias (EB), manifested as a hysteresis‐loop offset after field‐cooling, is demonstrated in perovskite‐structured ferromagnet/antiferromagnet (La0.67Sr0.33MnO3/YFeO3)nheterostructures grown on (100) SrTiO3substrates. Bilayer samples show an EB of 306 Oe at 50 K, whereas multilayers with five layers exhibit an exchange bias of up to 424 Oe at 50 K. A spin valve consisting of La0.67Sr0.33MnO3/SrTiO3/La0.67Sr0.33MnO3/YFeO3shows stable remanent configurations resulting from pinning of the upper La0.67Sr0.33MnO3layer by the YFeO3. In contrast, EB is not observed on (111)‐oriented SrTiO3substrates due to interface roughening. These results demonstrate YFeO3as an alternative orthoferrite antiferromagnet compared to BiFeO3and LaFeO3for incorporation into exchange‐biased heterostructures.
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Synthesis and Structure of an Ion‐Exchanged SrTiO 3 Photocatalyst with Improved Reactivity for Hydrogen Evolution
Abstract BaTiO3heated in an excess of SrCl2at 1150 °C converts to SrTiO3through an ion exchange reaction. The SrTiO3synthesized by ion exchange produces hydrogen from pH 7 water at a rate more than twice that of conventional SrTiO3treated identically. The apparent quantum yield for hydrogen production in pure water of the ion exchanged SrTiO3is 11.4% under 380 nm illumination. The catalyst resulting from ion‐exchange differs from conventional SrTiO3by having ≈2% residual Ba, inhomogeneous Cl‐doping at a concentration less than 1%, Kirkendall voids in the centers of particles that result from the unequal rates of Sr and Ba diffusion together with the transport of Ti and O, and nanoscale regions near the surface that have lattice spacings consistent with the Sr‐excess phase Sr2TiO4. The increased photochemical efficiency of this nonequilibrium structure is most likely related to the Sr‐excess, which is known to compensate donor defects that can act as charge traps and recombination centers.
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- PAR ID:
- 10400185
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Materials Interfaces
- Volume:
- 10
- Issue:
- 10
- ISSN:
- 2196-7350
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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