Browsing by Author "Zhang, Zaoli"

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Crossover between superconductivity and magnetism in SrRuO3 mesocrystal embedded YBa2Cu3O7-x heterostructures
(2016)
Suresh, Vandrangi
;
Lin, Jheng-Cyuan
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Liu, Heng-Jui
;
Zhang, Zaoli
;
Chiang, Ping-Chih
The competition between superconductivity and ferromagnetism poses great challenges and has attracted renewed interest for applications in novel spintronic devices. In order to emphasize their interactions, we fabricated a heterostructure composed of superconducting YBa2Cu3O7-delta (YBCO) film embedded with itinerant ferromagnetic SrRuO3 (SRO) mesocrystals. Starting from a doping concentration of 10 vol% of SRO mesocrystal in a YBCO matrix, corresponding to the density of SRO nanocrystals similar to 5 x 10(9) cm(-2), which exhibits the typical characteristic of a metal-superconductor transition, and then increasing the magnetic interactions as a function of SRO embedment, the electronic correlation and the interplay between superconductivity and magnetism throughout the temperature regime were investigated. A metal-insulator transition in the normal state of YBCO and a crossover between superconductivity and magnetism at low temperatures were found upon increasing the density of nano-size SRO crystallites in the YBCO matrix as a consequence of competing interactions between these two ordered phases.
Ultrafast Giant Photostriction of Epitaxial Strontium Iridate Film with Superior Endurance
(2018-12-01)
Yang, Jan-Chi
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Liou, Yi-De
;
Tzeng, Wen-Yen
;
Liu, Heng-Jui
;
Chang, Yao-Wen
Photostriction, optical stimulus driven mechanical deformation in materials, provides a solution toward next-generation technology. Here, the giant photostriction (similar to 2% change of lattice) of epitaxial strontium iridate (SrIrO3) films under illumination at room temperature is revealed via power-dependent Raman scattering, which is significantly larger as compared to conventional inorganic materials. The time scale and mechanism of this giant photostriction in SrIrO3 are further studied through time-resolved transient reflectivity measurements. The main mechanism is determined to be the electron-phonon coupling. In addition, we find that such an exotic behavior happens within few picoseconds and remains up to 107 cyclic on/off operations. The observation of giant photostriction in SrIrO3 films with superior endurance promises the advance of shape responsive solids that are sensitive to environmental stimuli, which could be widely utilized for multifunctional optoelectronics and optomechanical devices.