Browsing by Author "Hsiao, Yen-Fu"

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Effects of Strain and Ordering of Rare-Earth Element Moments on Magnetic-Reordering in Orthorhombic Multiferroic Manganites
(2013-10-01)
Hsiao, Yen-Fu
;
Lai, Jun-Yo
;
Lin, Jun-Yu
;
Fang, Hau-Wei
;
Hung, Yi-Tse
Orthorhombic multiferroic manganite thin films with various orientations and strain states were prepared to show the effects of anisotropic strain and antiferromagnetic (AFM) ordering of rare-earth f-electrons on the orientation of the incommensurate-to-commensurate AFM reordering. Systematic analyses suggest that the low-temperature AFM ordering of the rare-earth f-electrons may have played a decisive role in causing the orientation changes in AFM reordering, although the b-axis strain does have a significant influence on the zero-field magnetization behaviors. (C) 2013 The Japan Society of Applied Physics
Effects of strain on the electronic structure and magnetic properties in SrMn0.5Fe0.5O3
(2016-09-01)
Mi, Chun-Wei
;
Chin, Yi-Ying
;
Hsiao, Yen-Fu
;
Fang, Hau-Wei
;
Luo, Chih-Wei
The electronic structure and magnetic properties of SrMn0.5Fe0.5O3 powder and films grown on (100)-SrTiO3 (STO) and (100)-LaAlO3 (LAO) substrates by pulsed laser deposition (PLD) were investigated by temperature dependent magnetization and soft x-ray absorption. The results exhibit characteristics of 3d(5) Fe3+, 3d(5) (L) under bar Fe4+, and 3d(3) + 3d(4) (L) under bar Mn4+ at room temperature in all samples. However, the features of 3d(5) Fe3+ and 3d(3) Mn4+ increased significantly for SMFO/LAO at 35 K, which also displayed substantial competition between antiferromagnetic and ferromagnetic order well-above the Neel temperature of SrFeO3 (T-N similar to 134 K). We attributed this to being caused by charge disproportionation resulting from ligand-hole localization, which is more favorable to take place when the sample is under compressive strain.
Effects of Structural Strain and Rare-Earth Moments on Spin Cycloidal-Plane in Multiferroic Rare-Earth Manganites
(2016-05)
Hsiao, Yen-Fu
;
Kuo, Wei-Cheng
;
Mi, Chun-Wei
;
Chang, Kai-Ting
;
Luo, Chih-Wei
A series of orthorhombic multiferroic manganites (o-ReMnO3) thin films with deliberately designed strain states and different rare-earth elements were prepared to unveil the roles played by the strain and 4f-electron moments in determining the magnetic ordering and associated polarizations. The results obtained from temperature-dependent magnetization, dielectric and ferroelectric measurements revealed that the orientations of magnetic reordering and polarization varied with the specific rare-earth element involved. Namely, with the increase of total angular momentum J of the 4f-electrons of rare-earth element the orientation of magnetic reordering was changed from the b-axis (sinusoidal state) for Yb3+ to the a-axis (ab-cycloidal) for Tm3+ and, eventually to the c-axis (bc-cycloidal) for Er3+ and Ho3+. These results indicate that the Re-Mn magnetic exchange interaction plays a more important role than the external strain does in determining the magnetic and hence polarization states in multiferroic o-ReMnO3 manganites. Our results also confirmed the coexistence of different magnetic spin states in o-ReMnO3 thin films.
The Effect of Vapor Transport Annealing on FeSe Films Deposited on 2D Material
(2020-01-01)
Fitriyah, Nurul
;
Hong, Ten-Her
;
Duy, Ha Thai
;
Mi, Juinn-Wei
;
Hsiao, Yen-Fu
Owing to its simple crystal structure, tetragonal FeSe has been considered as a perfect candidate for investigating the interplays among the superconductivity, magnetism and structural phase transition. Previous works had revealed that superconductivity could only be seen in samples with Se deficiency for the otherwise ferromagnetic tetragonal FeSe. In this study, we investigated the effect of vapor transport annealing on the crystalline quality of FeSe films deposited on flexible muscovite (mica) substrates by pulsed laser deposition. The annealing processes were conducted by sealing FeSe powder in tandem with the as-deposited FeSe films in a quartz tube. The FeSe powder was placed at a distance of about 18.5 cm from the FeSe films and the entire sealed quartz tube (about 1.2 cm in diameter) assembly was put into a Lindberg three-zone furnace and maintained a temperature gradient between the two ends of the quartz tube. The results showed that FeSe films successfully grown on flexible mica substrates and the annealing did improve the morphology and crystallinity of the films, however, the films appeared to have more inhomogeneous phases. We suspect that this might be due to uncompleted FeSe phase nucleation in non-optimum condition. The interface between the muscovite substrate and the FeSe films also could be the caused of the formation of other impurity phases, such as FeSe2 and Fe3Se4. Consequently, the obtained films exhibited only paramagnetic behaviors, and there was no sign of zero-resistance down to 2 K.