http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Introduction of Brillouin Light Scattering for Spintronics Research
Jaehun Cho,June-Seol Kim,Chun-Yeol You 한국자기학회 2021 한국자기학회 학술연구발표회 논문개요집 Vol.31 No.2
We will explain about Brillouin Light Scattering (BLS), which is an in-elastic light scattering with magnon of the magnetic samples. Magnon excitation frequency (or spin-wave (SW) resonance frequency) is determined by the dispersion relations of SW as a function of the basic magnetic properties of the samples, sample’s geometrical structure, SW wavevector, and external magnetic field. In BLS measurement, we varied the external magnetic field and obtained the basic magnetic properties of the sample by non-linear regression process, so that we can determine the saturation magnetization, anisotropy energy, exchange stiffness. In addition, we can also determine the interfacial Dzyaloshinskii-Moriya Interaction (iDMI) energy density by using non-reciprocal nature of the SW with non-zero iDMI. Since BLS is based on optical measurement, BLS has a lateral resolution of the laser beam spot size (~50 um), and BLS can measure the magnetic properties of the sub-nm ferromagnetic films. In this lecture, we will discuss about basic principles of BLS measurement and application of BLS for spintronics devices researches.
Cho, Jaehun,Kim, Nam-Hui,Jung, Jinyong,Han, Dong-Soo,Swagten, Henk J. M.,Kim, June-Seo,You, Chun-Yeol IEEE 2018 IEEE transactions on magnetics Vol.54 No.6
<P>We investigate the interfacial Dzyaloshinskii–Moriya interaction (iDMI) and the perpendicular magnetic anisotropy (PMA) in the annealed inversion symmetry breaking structures (Pt/Co (CoFeB)/AlO<SUB><I>x</I></SUB> and Ta/CoFeB/AlO<SUB><I>x</I></SUB>) by Brillouin light scattering. The iDMI energy density of Pt/Co and Pt/CoFeB samples decreases while increasing annealing temperature, but the iDMI energy density of Ta/CoFeB sample slightly increases by increasing annealing temperature. By applying the thermal annealing process, PMA energies slightly increase at the Pt/Co interface; however, Pt/CoFeB, (Ta/CoFeB) structures are dramatically decreased (increased) by the annealing process. The effects of the annealing show complicate variation for iDMI and PMA for each structure; however, we find overall weak correlations between iDMI and PMA despite different materials and annealing process.</P>
브릴루앙 광산란을 이용한 자성박막에서의 자화 동역학연구
조재훈(Jaehun Cho),김준서(June-Seo Kim),유천열(Chun-Yeol You) 한국자기학회 2021 韓國磁氣學會誌 Vol.31 No.2
Brillouin light scattering (BLS) is used to measure thermally exited surface and bulk spinwave (SW) modes in various magnetic materials and it is to study SW frequency ranges up to sub-hundred GHz. In this review, we discuss magnetic properties on magnetic thin films including Heisenberg interaction, in-plane biaxial magnetic anisotropy, perpendicular magnetic anisotropy, Dzyaloshinskii-Moriya interaction probed by using a BLS spectroscopy.
Jung, Jaehun,Kim, Jun,Park, Gyurim,You, Youngmin,Cho, Eun Jin WILEY‐VCH Verlag 2016 Advanced Synthesis & Catalysis Vol.358 No.1
<P><B>Abstract</B></P><P>Two transformations initiated by photoinduced one‐electron transfer to α‐bromo ketones have been demonstrated. Hantzsch esters donate one electron to α‐bromo ketones under photoirradiation, promoting reductive debromination. Subsequent reactions of the resulting radical species of the ketones with molecular oxygen and Hantzsch esters lead to α‐hydroxylation or debromination, respectively. The relative dominance of the two pathways depends profoundly on the reaction conditions, including solvent, O<SUB>2</SUB> levels, and the concentration of the Hantzsch esters. The synthetic protocols feature advantages because they require the environmentally benign sources, molecular oxygen and visible light.</P>
두께변화에 대한 Ni<SUB>81</SUB>Fe<SUB>19</SUB> 박막의 자화 동역학 특성연구
조재훈(Jaehun Cho),김준서(June-Seo Kim),유천열(Chun-Yeol You) 한국자기학회 2021 韓國磁氣學會誌 Vol.31 No.5
The thickness dependent magnetic properties of Ni<SUB>81</SUB>Fe<SUB>19</SUB> thin film are investigated using Brillouin light scattering and Vector network analyzer-ferromagnetic resonance. Ni<SUB>81</SUB>Fe<SUB>19</SUB> thin films are fabricated by DC magnetron sputtering system as 15, 30, 50, 70 nm. The determined magnetic parameters are saturation magnetization (M<SUB>s</SUB>), exchange stiffness constant (A<SUB>ex</SUB>), and Gilbert damping constant (α). M<SUB>s</SUB> values are slightly increased as increasing Ni<SUB>81</SUB>Fe<SUB>19</SUB> thickness and decreased as increasing Ni<SUB>81</SUB>Fe<SUB>19</SUB> thickness. A<SUB>ex</SUB> values are almost identical value as 8.9 pJ/m, and α is decreased from 0.0113 ± 0.0001 to 0.0086 ± 0.0002 as increasing Ni<SUB>81</SUB>Fe<SUB>19</SUB> thickness.