https://scholar.dgist.ac.kr/handle/20.500.11750/87 2026-04-08T16:43:19Z 2026-04-08T16:43:19Z Hwang, Hee-Kyeong Kwon, Jaesuk Lee, Ki-Seung Hong, Jung-Il You, Chun-Yeol https://scholar.dgist.ac.kr/handle/20.500.11750/9468 2025-07-24T07:31:28Z 2018-10-31T15:00:00Z

Title: Memristive behavior of field-driven domain-wall motion in a width-modulated structure with multiple Hall crosses Author(s): Hwang, Hee-Kyeong; Kwon, Jaesuk; Lee, Ki-Seung; Hong, Jung-Il; You, Chun-Yeol Abstract: The remarkable property of a memristor is that it provides multiple resistance states by remembering the current or voltage history associated with the magnetic flux and charge in the device. We investigate the domain wall (DW) motion in a multiple Hall crosses (MHCs) structure to realize the memristive DW device. We fabricated perpendicular magnetic anisotropy (PMA) micro-wires for a [Co/Pt]4 multilayer stack, and they contain MHCs with various widths. When an external field is applied, a DW alternately passes through each Hall cross, thereby creating a hysteresis loop with various magnitudes of Hall resistance states depending on the DW position. Because the measured Hall signal relies on the DW position, which is a function of the history of the field, the basic requirements of a memristor are satisfied. In addition to the anomalous Hall signal, the movement of the DW in the PMA system by field pulses has been recorded using a Kerr microscope to confirm the DW position. The results reveal that the DW motion in the width-modulated MHCs system can be used as a promising test bed and/or application of the memristive DW-motion device. © 2018 Author(s).

2018-10-31T15:00:00Z Khan, A. Kaneko, H. Faruk, M.O. Alam, M.K. Kim, C. Naher, S. Suzuki, H. https://scholar.dgist.ac.kr/handle/20.500.11750/4279 2025-07-24T07:29:29Z 2016-12-31T15:00:00Z

Title: Geometric Spin Frustration in Zn1-xNixCr2O4 System Author(s): Khan, A.; Kaneko, H.; Faruk, M.O.; Alam, M.K.; Kim, C.; Naher, S.; Suzuki, H. Abstract: At room temperature, the cubic spinel ZnCr2O4 is known as the typical geometrically frustrated spin system. Upon cooling this compound undergoes a crystal structure change driven by removing the frustrated degenerated states, accompanying with the magnetic ordering. In the tetragonal phase the c-axis is larger than the a-axis. Another spinel compound NiCr2O4 takes the cubic structure above 310 K. Below 310 K NiCr2O4 is tetragonally distorted (c/a < 1) due to cooperative Jahn-Teller ordering. In the previous reports, the geometrical frustrated spin fluctuations still exist in NiCr2O4. In this report we investigated how the geometrical frustration changes and how the ratio of the crystal axis, c/a changes in Zn1-xNixCr2O4 system by the low temperature x-ray diffraction measurement and the SQUID magnetometer.

2016-12-31T15:00:00Z Song, Hyon-Seok Lee, Kyeong-Dong Sohn, Jeong-Woo Yang, See-Hun Parkin, Stuart S. P. You, Chun-Yeol Shin, Sung-Chul https://scholar.dgist.ac.kr/handle/20.500.11750/3251 2025-07-24T07:28:26Z 2013-03-10T15:00:00Z

Title: Observation of the intrinsic Gilbert damping constant in Co/Ni multilayers independent of the stack number with perpendicular anisotropy Author(s): Song, Hyon-Seok; Lee, Kyeong-Dong; Sohn, Jeong-Woo; Yang, See-Hun; Parkin, Stuart S. P.; You, Chun-Yeol; Shin, Sung-Chul Abstract: We investigate the intrinsic Gilbert damping constant in perpendicular magnetic anisotropy Co/Ni multilayer system by means of an all-optical method. We find that the intrinsic Gilbert damping constant does not depend on the stack number and the perpendicular magnetic anisotropy when the magnetic field is high enough. In contrast, the extrinsic Gilbert damping is strongly correlated with the inhomogeneous anisotropy distribution in the low-field regime, as observed in magneto-optical images. Intriguingly, the extrinsic Gilbert damping is consistently reduced with decreasing length scale in the measurements, providing a concrete means to determine the intrinsic Gilbert damping. © 2013 American Institute of Physics.

2013-03-10T15:00:00Z Lee, Kyeong-Dong Song, Hyon-Seok Kim, Ji-Wan Ko, Hyun Seok Sohn, Jeong-Woo Park, Byong-Guk Shin, Sung-Chul https://scholar.dgist.ac.kr/handle/20.500.11750/3006 2025-07-24T07:29:02Z 2014-10-31T15:00:00Z

Title: Gilbert damping and critical real-space trajectory of L1(0)-ordered FePt films investigated by magnetic-field-induction and all-optical methods Author(s): Lee, Kyeong-Dong; Song, Hyon-Seok; Kim, Ji-Wan; Ko, Hyun Seok; Sohn, Jeong-Woo; Park, Byong-Guk; Shin, Sung-Chul Abstract: The magnetization dynamics of perpendicularly magnetized FePt films is studied using both magnetic-field-induction and all-optical methods. A critically damped trajectory was observed in this system, where the precession ended within subnanoseconds after a single large oscillation. Using the Landau-Lifshitz-Gilbert (LLG) calculation with an experimental configuration, the effective anisotropy and damping constant were obtained. A damping constant of approximately 0.2 was determined after both a magnetic field and a laser pulse were used. The laser-induced real-space trajectory was well explained by the modified LLG calculation taking into account the demagnetization and time-dependent anisotropy. © 2014 The Japan Society of Applied Physics

2014-10-31T15:00:00Z