Browsing by Author "Lin, Po-Jung"

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A NOVEL NANOELECTROMAGNETIC SYSTEM USING MULTIFERROIC/MAGNETOELECTRIC NI-NANO-CHEVRON/PMN-PT HETEROSTRUCTURE TO DEMONSTRATE AN ELECTRIC -FIELD -CONTROLLED PERMANENT MAGNETIC SINGLE -DOMAIN TRANSFORMATION
(2018-01-01)
Cheng, Chih-Cheng
;
Lin, Shin-Hung
;
Chen, Yu-Jen
;
Wang, Hsin-Min
;
Chu, Hou-Jen
In this paper, we report a novel nanoelectromagnetic system using multiferroic/magnetoelectric Ni-nanochevron/PMN-PT heterostructure to demonstrate an electric field -controlled permanent magnetic single-domain transformation. The heterostructure consists of a magnetostrictive Ni-nano-chevron, Pt top and bottom electrodes, and a piezoelectric PMN-PT substrate. In initial state (as demagnetized), the magnetization of the magnetic single domain is stably along the long axis of the nano-chevron. A magnetic field of 3000 Oe (along 45 degree of nano-chevron) is applied to magnetize the Ni-nano-chevron from stable single domain to metastable two-domains. After this, an electric field of 0.8MV/m is applied to the PMN-PT substrate to produce the converse magnetoelectric effect to transform the two-domains. After the electric field is removed, the two-domains are further transformed back to the single-domain. Finally, when comparing the domains before and after applying our approach, approximately 50 % of single-domains are successfully and permanently switched (i.e., magnetization-direction is permanently rotated 180 degrees).
ELECTRICAL CONTROL OF MAGNETIC MULTI-DOMAIN TRANSFORMATION IN A SPECIFIC GEOMETRIC-PATTERNED NI NANOSTRUCTURE ON A PIEZOELECTRIC [PB(MG(1/3)NB(2/3))O3](0.68)-[PBTIO3](0.32) SUBSTRATE
(2016)
Chen, Yu-Jen
;
Chung, Tien-Kan
;
Lin, Po-Jung
;
Hung, Chiao-Fang
;
Chu, Hou-Jen
In this paper, we report an electrical control of magnetic multi-domain-walls transformation in an N-shape-patterned Ni nanostructures on a piezoelectric [Pb(Mg1/3Nb2/3)O-3](0.68)-[PbTiO3](0.32) substrate. Based on the converse-magnetoelectric-effect induced domain-wall transformation and the specific N-shape geometry guided domain-wall motion, the domain walls are successfully transformed by an applied electric field of 0.8 MV/m from the transverse domain wall state into the flux closure vortex domain state. These experimental results achieve the electrical control of multi-domain-walls transformation and would create more data storage and memory applications in the future.
Growth characteristics of Fe-doped GaN epilayers on SiC (001) substrates and their effects on high breakdown voltage devices
(2020-11-15)
Chang, Kai-Ping
;
Lin, Po-Jung
;
Horng, Ray-Hua
;
Wuu, Dong-Sing
;
電子工程學系及電子研究所
The growth characteristics of Fe-doped GaN epitaxial layers on semi-insulating SiC (001) substrates were studied using metalorganic chemical vapor deposition for high breakdown voltage device applications. A smooth Fe-doped GaN epilayer surface can be realized by changing the ferrocene flow, while higher Fe concentrations in the GaN epilayer affect the surface morphology. To reduce the Fe trapping carrier and the sheet resistances of the two-dimension electron gas generated from the interface of AlGaN and GaN, the thickness ratio of Fe-doped and undoped GaN bi-epilayers was also optimized. AlGaN/GaN high electron mobility transistors with the optimum doping concentration of Fe-doped GaN and suitable thickness of undoped GaN have been successfully developed. The achieved breakdown voltage of the Fe-doped GaN epitaxial layer can be as high as 2457 V, which is attributed to the Fe-doped GaN epitaxial layer with higher resistance, which can sustain the high breakdown voltage. The details of the correlation between the surface morphology, Fe concentration, and thickness of Fe-doped GaN epitaxial layers used for high breakdown voltage devices will be also discussed in this paper.
Magnetic-field-assisted electric-field-controlled rotation of magnetic stripe domains in a magnetoelectric Ni microbar/[Pb(Mg1/3Nb2/3)O-3](0.68)-[PbTiO3](0.32) heterostructure
(2016-04)
Chung, Tien-Kan
;
Wang, Hsin-Min
;
Chen, Yu-Jen
;
Lin, Shin-Hung
;
Chu, Hou-Jen
We report a magnetic-field-assisted electric-field-controlled approach to rotate magnetic stripe domains in a magnetoelectric Ni-microbar/[Pb(Mg1/3Nb2/3)O-3](0.68)-[PbTiO3](0.32) heterostructure. A magnetic field is applied for magnetizing the microbar\'s stripe domains along the microbar\'s short/magnetic-hard axis. Subsequently, an electric field is applied for induction of a transformation of domains through the converse magnetoelectric effect. Owing to the microbar\'s geometry, the transformation causes the stripe domains to rotate away from the short/magnetichard axis toward the long/magnetic-easy axis. The rotation angle increases in proportion to the increasing electric field intensity. A maximal rotation of 90 degrees is obtained at the electric field intensity of 0.8MV/m. The rotation state persists after removing the electric field. (C) 2016 The Japan Society of Applied Physics