https://scholar.dgist.ac.kr/handle/20.500.11750/831 2026-04-04T14:59:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/58509 Title: Electrical modulation of spin-orbit torque efficiencies in electric-double-layer gated Pt/Co/Pt trilayer Author(s): 이수범; 안수혁; 백은총; 조재용; 김동률; 유천열 Abstract: Spin current electrically generated via spin-orbit coupling exerts so-called spin-orbit torque onto ferromagnetic materials. Until now, much effort has been devoted to engineering spin-orbit torque by modifying film structure. In this method, however, spin-orbit torque could not be controlled after the device fabrication. Despite the versatile applications of spin-orbit torque in manipulating magnetic materials, the absence of dynamic tunability for spin-orbit torque has constrained the potential for constructing spin-orbit torque-based logic gates[1]. Furthermore, dynamic control of spin-orbit torque provides a novel function for the future spin-orbit torque devices. Here we focus on the electric double layer created at a polarized electrolyte/channel surface, which enables a tunable spin-charge interconversion in ultrathin Pt films through the utilization of an electric double layer[2]. In this study, we report the electrical modulation of spin-orbit torque efficiencies using electric-double-layer gating in a Pt/Co/Pt trilayer system with Ta seed layer, where the opposing spin-orbit torques from the top and bottom Pt layers cancel out each other. Harmonic Hall measurements with electric-double-layer gating reveal that the damping-like torque efficiency is switched on or off, as shown in Fig. 1. A more detailed discussion will be given in the presentation. 2023-11-22T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/57887 Title: Improved the conductivity of PEDOT:PSS by magnetic field for bio-electrode applications Author(s): Doe, Juha; Choi, Hyeokjoo; Lee, Sungwon; You, Chun-Yeol Abstract: Poly(3,4-ehtylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) is a mixture of two ionomers. Especially, its conductive polymer PEDOT is well-known conductive polymer widely utilized for organic and stretchable device fabrication. However, PEDOT:PSS itself is not conductive polymer owing to another ionomer PSS so that pretreatment is necessary to enable PEDOT. Recently, it is found that hydrothermal (HT) treatment significantly increases the activity of PEDOT:PSS up to 250 times [1]. Also, this treatment has advantages in that it is compatible with biological environments since it doesn’t leave organic solution or strong acid. Here, we introduce additional improvement of PEDOT:PSS activation, more than twice, applying magnetic field over hydrothermal treatment. We also exhibit analysis of molecular structure with Raman spectroscopy, XPS, and GIWAXS. The results shows enhanced attraction force between PEDOT:PSS and water molecules. 2024-05-30T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/57699 Title: Effect of sputtering power on the magnetic properties in Pt/Co system for spin-orbit torque devices Author(s): Cho, Jae Yong; Baek, Eunchong; An, Suhyeok; Lee, Soobeom; You, Chun-Yeol Abstract: As CMOS integration continues to advance, the semiconductor industry faces several challenges. Spintronics has emerged as a promising technology to go “beyond CMOS” and overcome these limitations.[1] Spintronics is a field of research that ut ilizes not just electron charge but also electron spin, introducing a new degree of freedom. The key materials employed in spintronics predominantly consist of magnetic materials. Although there are wide variety of categories in magnetic materials, perpendicular magnetic anisotropy (PMA) which prefer magnetization alignment perpendicular to the film plane gets significant notice because of its advantage in terms of information density.[2] To control these magnetic elements, techniques like spin-transfer torque (STT) and spin-orbit torque (SOT) are utilized. Notably, the SOT method offers the advantage of high speed and is gaining attention in various devices.[3]To improve better SOT devices, researchers aim to manipulate the material properties of magnetic materials using a range of methods.[4] In particular, there are several research exploring how variations in sputtering power can influence material properties.[5][6] Given this, we hypothesized that altering the sputtering power would likewise lead to changes in the physical properties of the magnetic material. In this report, we investigate the impact of the deposition power of the Co layer on the material properties in the Pt/Co bilayer structure, which is a representative system exhibiting PMA characteristics and controllable through SOT. The structure was deposited using a magnetron DC sputtering method on an oxidized silicon substrate with a thickness of 300 nm. Sputtering power was varied from 40W to 80W at 10W intervals. We confirmed how this variation in deposition power affects magnetic anisotropy. We believe that this research holds significant potential for advancing the development of spintronic SOT based devices that rely on PMA. 2023-11-21T15:00:00Z https://scholar.dgist.ac.kr/handle/20.500.11750/56797 Title: Spin wave dynamics in epitaxial antiferromagnetic α-Fe₂O₃ thin film prepared by pulsed laser deposition method Author(s): Kim, Soo-Jung; Ha, Jae-Hyun; Baek, Eunchong; Kim, Jun-Su; Hong, Jung-Il; You, Chun-Yeol Abstract: Spin wave dynamics in antiferromagnetic materials, which has large group velocity (over 20 km/s) and long diffusion length (up to 10 μm), is getting more attention in many fields. [1-2] Especially, the α-Fe2O3, which has high bulk Dzyaloshinskii-Moriya interaction (DMI), low Gilbert damping constant (~10-5) and relatively low resonance frequency (tens to hundreds of GHz frequency) than other antiferromagnetic materials (over THz frequency), is emerging as a promising material recently. [3-5] However, the relevant spin wave dynamics studies are mostly dealing with the bulk single crystal structure, which shows considerably different characteristics in epitaxial thin film structure.In this study, we investigate the unique characteristics of spin wave dynamics in the α-Fe2O3 thin film at room temperature. The sample is deposited by using pulsed laser deposition (PLD) system with 85 nm of epitaxial Fe2O3 on the c-plane Al2O3 substrate. We confirm the crystallinity by X-ray diffractometer (XRD) and check the magnetic properties using SQUID-VSM. To measure the special features of spin wave dynamics in the α-Fe2O3 thin film, we used ferromagnetic resonance (FMR) and micro-Brillouin light scattering (μBLS). We detect the unexpected low frequency mode (f-) and multiple peaks of BLS signal which could be the clue of the new properties. Our results can widen the insight of the spin wave dynamics in the thin film α-Fe2O3 and the usage in the antiferromagnetic spintronics applications. 2023-11-21T15:00:00Z