12,938 research outputs found
Growth and characterization of superconductor-ferromagnet thin film heterostructure la1.85sr0.15cuo4/srruo3
No full text© 2021, Korea Institute of Applied Superconductivity and Cryogenics. All rights reserved.Superconductor-ferromagnet thin film heterostructure is an ideal system for studying the interplay between superconductivity and ferromagnetism. These two antagonistic properties combined in thin film heterostructure create interesting proximity effects such as spin-triplet superconductivity. Thin film heterostructure of optimally doped La2-xSrxCuO4(LSCO) cuprate superconductor and SrRuO3(SRO) ruthenate ferromagnet has been grown by pulsed laser deposition. Its temperature-dependent resistivity and Hall effect measurements show that our LSCO/SRO heterostructure has both superconductivity and ferromagnetism. In the Hall effect measurement results, we find additional hump-like structures appear in the anomalous Hall effect signal in the vicinity of superconducting transition. We conclude that giant magnetoresistance of the LSCO layer distorts the AHE signal, which results in a hump-like structure.11Nscopuskc
Ferromagnetic insulating substrate for magnetic proximity studies: LaCoO3 thin film
No full textFerromagnetic insulators (FMIs) are intriguing not only due to their rare nature, but also due to their potential applications in spintronics and various electronic devices. One of its key promising applications is based on an FMI-induced magnetic proximity effect, which can impose an effective time-reversal symmetry breaking on the target ultrathin layer to realize novel emergent phenomena. Here, we conduct systematic studies on thin film LaCoO3, an insulator known to be ferromagnet under tensile strain, with varying thicknesses, to establish it as an FMI platform to be integrated in heterostructures. The optimal thickness of the LaCoO3 layer, providing a smooth surface and robust ferromagnetism with large remanence, is determined. A heterostructure consisting of an ultrathin target layer (2 uc SrRuO3), the LaCoO3 FMI layer, and the La0.5Sr0.5CoO3 conducting layer has been fabricated and the angle-resolved photoemission spectroscopy measurement on the multi-layer system demonstrates a sharp Fermi edge and a well-defined Fermi surface without the charging effect. This demonstrates the feasibility of the proposed heterostructure using LaCoO3 thin film as the FMI layer, and further lays a groundwork to investigate the magnetic proximity induced phases in quantum materials.11Nsciescopu
Active-Clamp Forward Converter With Asymmetric Transformer Turns For Reducing Transformer DC Offset Current
No full textCapping and gate control of anomalous Hall effect and hump structure in ultra-thin SrRuO3 films
No full text© 2021 Author(s).Ferromagnetism and exotic topological structures in SrRuO3 (SRO) induce sign-changing anomalous Hall effect (AHE). Recently, hump structures have been reported in the Hall resistivity of SRO thin films, especially in the ultra-thin regime. We investigate the AHE and hump structure in the Hall resistivity of SRO ultra-thin films with an SrTiO3 (STO) capping layer and ionic liquid gating. STO capping results in sign changes in the AHE and modulation of the hump structure. In particular, the hump structure in the Hall resistivity is strongly modulated and even vanishes in STO-capped 4 unit cell films. In addition, the conductivity of STO-capped SRO ultra-thin films is greatly enhanced with restored ferromagnetism. We also performed ionic liquid gating to modulate the electric field at SRO/STO interface. Drastic changes in the AHE and hump structure are observed with different gate voltages. Our study shows that the hump structure as well as the AHE can be controlled by tuning inversion symmetry and the electric field at the interface.11Nsciescopu
Growth and Electronic Structure of Copper Oxide Monolayer Epitaxial Films
No full textCopper-basedhigh-temperature superconductors share acommon featurein their crystal structure, which is the presence of a CuO2 plane, where superconductivity takes place. Therefore, importantquestions arise as to whether superconductivity can exist in a singlelayer of the CuO2 plane and, if so, how such superconductivityin a single CuO2 plane differs from that in a bulk cupratesystem. To answer these questions, studies of the superconductivityin cuprate monolayers are necessary. In this study, we constructeda heterostructure system with a La2-x Sr x CuO4 (LSCO) monolayercontaining a single CuO2 plane and measured the resultingelectronic structures. Monolayer LSCO has metallic and bulk-like electronicstructures. The hole doping ratio of the monolayer LSCO is found todepend on the underlying buffer layer due to the interface effect.Our work will provide a platform for research into ideal two-dimensionalcuprate systems.11Nsciescopu
Author Correction: Evaluation of skin cancer resection guide using hyper‑realistic in‑vitro phantom fabricated by 3D printing
No full textThe original version of this Article contained an error in the spelling of the author Taehun Kim which was incorrectly given as Teahun Kim. The original Article has been corrected
Observation of metallic electronic structure in a single-atomic-layer oxide
No full text© 2021, The Author(s).Correlated electrons in transition metal oxides exhibit a variety of emergent phases. When transition metal oxides are confined to a single-atomic-layer thickness, experiments so far have shown that they usually lose diverse properties and become insulators. In an attempt to extend the range of electronic phases of the single-atomic-layer oxide, we search for a metallic phase in a monolayer-thick epitaxial SrRuO3 film. Combining atomic-scale epitaxy and angle-resolved photoemission measurements, we show that the monolayer SrRuO3 is a strongly correlated metal. Systematic investigation reveals that the interplay between dimensionality and electronic correlation makes the monolayer SrRuO3 an incoherent metal with orbital-selective correlation. Furthermore, the unique electronic phase of the monolayer SrRuO3 is found to be highly tunable, as charge modulation demonstrates an incoherent-to-coherent crossover of the two-dimensional metal. Our work emphasizes the potentially rich phases of single-atomic-layer oxides and provides a guide to the manipulation of their two-dimensional correlated electron systems.11Nsciescopu
A novel accurate primary side control (PSC) method for half-bridge (HB) LLC converter
No full textRecently, several researches have been progressed on the primary-side control (PSC) methods which decrease the size and cost of the control stage. However, most of the researches have been applied to the flyback converter, and they have some challenges in applying them to the half-bridge (HB) LLC converter due to the large voltage across the secondary leakage inductor of the transformer. In this letter, a new PSC method for the HB LLC converter is proposed to obtain accurate output voltage. In the proposed method, the output voltage is regulated by obtaining the voltage across the primary side of the transformer when the external resonant inductor voltage becomes 0 V. At this time, since the voltage across the transformer secondary leakage inductor is small, the proposed method can accurately regulate the output voltage. A 400 V input and 20 V/85 W output laboratory prototype is built and tested to verify the effectiveness of the proposed PSC method
A simple control scheme for improving light-load efficiency in a full-bridge LLC resonant converter
No full textIn this paper, a load adaptive phase-shift control is proposed for the full-bridge LLC resonant converter to improve light-load efficiency. The proposed method reduces the effective duty ratio and the magnetizing current. Therefore, the core loss on transformer and the turn-off switching loss on switches are significantly reduced. To confirm the validity of this study, the prototype with 320~400V DC input, 12V/40A DC output is experimented
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