https://scholar.dgist.ac.kr/handle/20.500.11750/37 2026-10-27T10:04:23Z https://scholar.dgist.ac.kr/handle/20.500.11750/60997 Title: Reversal of interlayer exchange coupling through post-annealing process accompanying asymmetric crystallization in Ta/Co2Fe6B2/MgO/Co2Fe6B2/ MgO heterostructures Author(s): Kim, Tae-Hwan; Cho, Jaehun; Kim, Soojung; Hong, Jung-Il; Kim, June-Seo Abstract: The effect of the post-annealing process accompanying asymmetric crystallization on interlayer exchange coupling in the Ta/Co2Fe6B2/MgO/Co2Fe6B2/MgO heterostructure is systematically investigated using ferromagnetic resonance. To induce structural asymmetry, the bottom Co2Fe6B2 layer is in contact with a Ta buffer, which acts as a boron absorber, while the top Co2Fe6B2 layer is encapsulated between two MgO layers. Structural analysis and magnetization measurements confirm that the selective crystallization of the bottom Co2Fe6B2 layer is well established upon a thermal annealing process, while the top Co2Fe6B2 layer is remained as a disordered state. The ferromagnetic resonance spectra reveal distinct coupling regimes depending on the annealing state. In as-grown samples, an antiferromagnetic (AFM)-like coupling is observed for MgO thicknesses, tMgO above 2.0 nm. In particular, the post-annealing process can trigger a sign reversal of the interlayer exchange coupling to a ferromagnetic (FM)-like state in the thick spacer regime (tMgO ≥2.6 nm). 2026-08-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/60968 Title: Electrical Tuning of Ferrimagnetic Spin Alignment Angle and Compensation Temperature in Pt/IrMn3/CoGd Multilayers Author(s): Choi, Won- Chang; Sim, Tae- Bo; Park, Kwonjin; Kim, Tae- Hwan; Lee, Soobeom; Tran, Bao Xuan; Kim, Soojung; You, Chun- Yeol; Hong, Jung- Il Abstract: Compensation temperature (T M) is a characteristic parameter for a ferrimagnetic (FIM) material that requires careful consideration in the functional applications of FIM spintronics. Attempts at precise and localized control of T M have remained rare and challenging, but apparently a worthy issue for the expansion of spintronics to include FIMs. Conventional approaches such as thermal annealing or ion injection suffer from limited spatial selectivity and switching speed. Here, we show a novel route to control the T M of FIM by manipulating the alignments of the constituent spins through spin-orbit torque (SOT)-controlled exchange couplings with adjacent antiferromagnets. At the interface between antiferromagnetic IrMn3 and FIM CoGd multilayers, it was found that the antiferromagnet established firm exchange couplings with Co atoms, but negligible couplings with Gd. Such selective coupling modified the traditionally known collinear antiparallel arrangement of CoGd spins into a noncollinear spiral spin configuration, and the T M was found to correspondingly change significantly. Additionally, precise tuning of FIM properties through the modulation of SOT amplitude and application time was demonstrated, establishing an efficient electrical pathway for controlling the compensation phenomena in ferrimagnetic systems. 2026-09-30T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/60590 Title: A comparative synthesis study of α-MnTe across solid-state, Arc-melting, and Te-flux routes Author(s): Kim, Bomin; Jeong, Yunseong; Baek, Wonjung; Kim, Hobyeong; Rhee, Taeseong; Cho, Beopgil; Choi, Woo-Jae; Ha, Jae-Hyun; Park, Jaemun; Hong, Jung-Il; Kwon, Yong Seung; Seo, Jungpil; Park, Keeseong Abstract: Although alpha-MnTe has attracted renewed interest in both thermoelectric and altermagnetic contexts, direct comparisons of practically accessible synthesis routes within a common experimental framework remain limited. Here, we compare conventional solid-state reaction, arc melting and Te self-flux growth methods under a common framework of composition control and thermal history. Within the explored conditions, the phase outcome depends not only on the nominal starting composition but also on route-dependent synthesis environments, including volatilization in sealed ampoules, repeated remelting and rapid quenching in arc melting, and crystal-flux interfacial segregation in Te self-flux growth. In the solid-state route, slow heating with a slightly Mn-rich starting composition was associated with reduced MnTe2 and alpha-MnTe-dominant products. Arc melting yielded alpha-MnTe-dominant products without post-annealing, accompanied by dendritic-like microstructures. Te self-flux growth yielded single crystals, although a minor MnTe2-rich interfacial or surface layer often remained. While the present dataset does not define a rigorous phase boundary or a definitive mechanistic model, it provides a systematic comparative framework for route-dependent phase outcomes and impurity persistence in alpha-MnTe synthesis. 2026-07-31T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/60502 Title: A comparative synthesis study of α-MnTe across solid-state, Arc-melting, and Te-flux routes Author(s): Kim, Bomin; Jeong, Yunseong; Baek, Wonjung; Kim, Hobyeong; Rhee, Taeseong; Cho, Beopgil; Choi, Woo-Jae; Ha, Jae-Hyun; Park, Jaemun; Hong, Jung-Il; Kwon, Yong Seung; Seo, Jungpil; Park, Keeseong Abstract: Although alpha-MnTe has attracted renewed interest in both thermoelectric and altermagnetic contexts, direct comparisons of practically accessible synthesis routes within a common experimental framework remain limited. Here, we compare conventional solid-state reaction, arc melting and Te self-flux growth methods under a common framework of composition control and thermal history. Within the explored conditions, the phase outcome depends not only on the nominal starting composition but also on route-dependent synthesis environments, including volatilization in sealed ampoules, repeated remelting and rapid quenching in arc melting, and crystal-flux interfacial segregation in Te self-flux growth. In the solid-state route, slow heating with a slightly Mn-rich starting composition was associated with reduced MnTe2 and alpha-MnTe-dominant products. Arc melting yielded alpha-MnTe-dominant products without post-annealing, accompanied by dendritic-like microstructures. Te self-flux growth yielded single crystals, although a minor MnTe2-rich interfacial or surface layer often remained. While the present dataset does not define a rigorous phase boundary or a definitive mechanistic model, it provides a systematic comparative framework for route-dependent phase outcomes and impurity persistence in alpha-MnTe synthesis. 2026-07-31T15:00:00Z