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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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This content will become publicly available on February 3, 2027
Transient Terahertz Oscillations During Photoinduced Polarization Topology Reconfiguration in Ferroelectric Superlattices
ABSTRACT Terahertz resonances embedded in crystalline heterostructures could close a spectral gap between conventional electronics and photonics while opening new windows on phenomena in non‐equilibrium lattice dynamics. We show that femtosecond optical screening of the depolarization field in epitaxial PbTiO3/SrTiO3superlattices launches a collective polar mode that oscillates near 1 THz and coherently spans the entire mini‐Brillouin zone. Wave‐vector‐resolved pump–probe X‐ray diffraction resolves a nearly dispersion‐less oscillation at 0.87 and 0.94 THz at the zone boundary and zone center, respectively, persisting for ∼2.5 ps, corresponding to a weakly damped resonance. Dynamical phase‐field simulations reveal the origin of the mode to mesoscopic rotation of closure‐domain textures during the photoexcited transition from an unscreened to a screened electrostatic state. Varying the PbTiO3and SrTiO3ratio tunes the mode frequency continuously from 0.9 to 1.4 THz, providing a quantitative design rule for frequency‐selectable THz oscillators in ferroelectric heterostructures. By coupling nanoscale polarization reconfiguration to long‐wavelength coherent dynamics, this work establishes depolarization‐field engineering to topology‐driven THz functionality and expanding the landscape of collective lattice dynamics.
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- Award ID(s):
- 2237884
- PAR ID:
- 10684287
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Advanced Science
- ISSN:
- 2198-3844
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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