Browsing by Author "Mi, Chun-Wei"

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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.