A5080551562- Magnetic properties of thin films
- Advanced Memory and Neural Computing
- Magnetic and transport properties of perovskites and related materials
- ZnO doping and properties
- Quantum and electron transport phenomena
- Theoretical and Computational Physics
- Magnetic Properties and Applications
- Physics of Superconductivity and Magnetism
- Multiferroics and related materials
- Magnetic Field Sensors Techniques
- Magneto-Optical Properties and Applications
- Characterization and Applications of Magnetic Nanoparticles
- Physical Unclonable Functions (PUFs) and Hardware Security
- Advanced Condensed Matter Physics
- Integrated Circuits and Semiconductor Failure Analysis
- Heusler alloys: electronic and magnetic properties
- Graphene research and applications
- Ferroelectric and Negative Capacitance Devices
- Topological Materials and Phenomena
- Surface and Thin Film Phenomena
- HVDC Systems and Fault Protection
- Electronic and Structural Properties of Oxides
- Magnetic Properties and Synthesis of Ferrites
- Near-Field Optical Microscopy
- Power Systems and Technologies
Korea Advanced Institute of Science and Technology
2019-2024
Gachon University
2023-2024
Yonsei University
2009-2022
University of Ulsan
2021
LS Cable & System (South Korea)
2010
LG (South Korea)
2010
The orbital Hall effect describes the generation of current flowing in a perpendicular direction to an external electric field, analogous spin effect. As carries angular momentum as does, injection into ferromagnet can result torque on magnetization, which provides way detect With this motivation, we examine current-induced spin-orbit torques various ferromagnet/heavy metal bilayers by theory and experiment. Analysis magnetic reveals presence contribution from heavy metal, competes with In...
Spin Hall effect, an electric generation of spin current, allows for efficient control magnetization. Recent theory revealed that orbital effect creates which can be much larger than Hall-induced current. However, current cannot directly exert a torque on ferromagnet, requiring conversion process from to Here, we report two effective methods the through spin-orbit coupling engineering, us unambiguously demonstrate orbital-current-induced torque, or torque. We find is greatly enhanced by...
While it is often assumed that the orbital response suppressed and short ranged due to strong crystal field potential quenching, we show can be remarkably long in ferromagnets. In a bilayer consisting of nonmagnet ferromagnet, spin injection from interface results accumulation torque which rapidly oscillate decay by dephasing. contrast, even when an external electric applied only on nonmagnet, find substantially long-ranged induced angular momentum go far beyond dephasing length. This...
Abstract Graphene is currently at the forefront of cutting-edge science and technology due to exceptional electronic, optical, mechanical, thermal properties. However, absence a sizeable band gap in graphene has been major obstacle for application. To open control functionalized graphene, several gapping strategies have developed. In particular, hydrogen plasma treatment triggered great scientific interest, because it known be an efficient way modify surface single-layered apply standard...
The electrical control of antiferromagnetic moments is a key technological goal antiferromagnet-based spintronics, which promises favourable device characteristics such as ultrafast operation and high-density integration compared to conventional ferromagnet-based devices. To date, the manipulation by electric current has been demonstrated in epitaxial antiferromagnets with broken inversion symmetry or interfaced heavy metal, spin-orbit torque (SOT) drives domain wall. Here, we report...
Physical unclonable function (PUFs) utilize inherent random physical variations of solid-state devices and are a core ingredient hardware security primitives. PUFs promise more robust information than that provided by the conventional software-based approaches. While silicon- memristor-based advancing, their reliability scalability require further improvements. These currently limited output fluctuations associated additional peripherals. Here, highly reliable spintronic exploit field-free...
Magnetic random-access memory (MRAM), which stores information through control of the magnetization direction, offers promising features as a viable nonvolatile alternative, including high endurance and successful large-scale commercialization. Recently, MRAM applications have extended beyond traditional memories, finding utility in emerging computing architectures such in-memory probabilistic bits. In this work, we report highly reliable MRAM-based security devices, known physical...
Abstract Spin‐orbit torque (SOT), arising from spin currents induced by the Hall effect, enables efficient electrical switching of magnetization. However, for practical application in spintronic devices, current must be reduced. Recent studies have shown that orbital conductivity is much larger than various transition metals, prompting investigations to exploit it enhance SOT efficiency. Despite extensive research on currents, a demonstration showing orbital‐current‐induced (OT) surpassed...
Magnetic and spintronic media have offered fundamental scientific subjects technological applications. Magneto-optic Kerr effect (MOKE) microscopy provides the most accessible platform to study dynamics of spins, magnetic quasi-particles, domain walls. However, in research nanoscale spin textures state-of-the-art devices, optical techniques are generally restricted by extremely weak magneto-optical activity diffraction limit. Highly sophisticated, expensive electron scanning probe methods...
We investigate the magnetoresistance of ferrimagnetic GdFeCo across magnetization compensation temperature ${T}_{\mathrm{M}}$. The magnetic field dependence longitudinal resistivity (${\ensuremath{\rho}}_{\mathrm{xx}}$) shows opposite trends below and above ${T}_{\mathrm{M}}$, variation ${\ensuremath{\rho}}_{\mathrm{xx}}$ with $B$ becomes more significant as decreases. observed unconventional is attributed to sperimagnetism GdFeCo. Further investigations on transverse...
Abstract Spin Seebeck effect (SSE) refers to the generation of an electric voltage transverse a temperature gradient via magnon current. SSE offers potential for efficient thermoelectric devices because geometry enables utilize waste heat from large-area source by greatly simplifying device structure. However, suffers low conversion efficiency that must be improved widespread application. Here we show substantially enhances oxidizing ferromagnet in normal metal/ferromagnet/oxide structures....
Low-energy proton irradiation was applied to pattern an array of metallic, ferromagnetic nanoislands through the local phase transformation oxidic, paramagnetic in a complex superlattice composed repetitions oxidic and metallic layer. The inflicted minimal damage on structure, resulting absence unwanted defects side effects. This nondestructive transfer clearly confirmed by contrast between irradiated unirradiated regions electrical, chemical, magnetic images. Simulation based properties...
Abstract Physical unclonable functions (PUFs), which exploit uncontrollable and unpredictable randomness of materials or devices, have been investigated as a hardware‐based security primitive owing to their robustness against adversarial attacks. Spin–orbit torque (SOT) switching is one the promising techniques for PUF applications because it can provide by stochastic distribution perpendicular magnetization. In this study, improvement in reliability SOT‐based PUFs external magnetic fields...
Abstract Unidirectional Spin Hall magnetoresistance (USMR) is a non-linear phenomenon recently observed in ferromagnet (FM)/nonmagnetic metal (NM) bilayer structures. Two very different mechanisms of USMR have been proposed; one relies on the current-direction-dependence electron-magnon scattering FM layer, and other spin accumulation at FM/NM interface. In this study, we investigate epitaxial Cr/Fe bilayers finding that significantly enhanced when Fe magnetization aligned to particular...
A magnetic Bloch line (BL) is a nanoscale topological defect with nontrivial charge. Herein, we propose novel memory that utilizes current-driven BL motion. We demonstrate it possible to write and shift BLs using spin-transfer-torque scheme. The writing efficiency shifting velocity of the BL-based racetrack are better than or comparable those domain wall (DW)-based memory. Moreover, motion more robust against defects DW motion, suggesting BL-motion-based can serve as next-generation beyond...
Abstract Current-induced spin-orbit torque (SOT) provides efficient magnetization control in spintronic devices. However, applications of SOT are limited, as deterministic switching perpendicular typically requires an external magnetic field. To overcome this, various approaches have been developed for field-free switching, including lateral symmetry breaking to generate out-of-plane SOT. In this study, we demonstrate with a 4-fold enhancement the ratio [Co/Ni] ferromagnetic multilayers...
In‐situ Raman spectroscopy was performed on chemical vapor deposited graphene microbridge (3 μm × 80 μm) under electrical current density up to 2.58 10 8 A/cm 2 in ambient conditions. We found that both the G and G′ peak of spectra do not restore back initial values at zero current, but slightly higher after switching off through microbridge. The up‐shift peak, is believed be due p‐doping by oxygen adsorption, which confirmed scanning photoemission microscopy. Both C–O C=O bond components C1...
We studied the dependence of exchange coupling on cooling-field strength in an exchange-biased spin valve with a synthetic antiferromagnetic layer by experiment and theory. Our theory calculates magnetic anisotropy energies each composing during field-cooling process, finds minimum state total energy, explains how magnetizations layers interact one another under various strengths. Calculations based well match results experimental measurements. observation shows that has to carefully choose...
Orbital anisotropy at interfaces in magnetic heterostructures has been key to pioneering spin-orbit-related phenomena. However, modulating the interface's electronic structure make it abnormally asymmetric challenging because of lack appropriate methods. Here, authors report that low-energy proton irradiation achieves a strong level inversion asymmetry and unusual strain [Co/Pd] superlattices through nondestructive, selective removal oxygen from Co
Abstract Spin‐orbit torque (SOT) promises fast and reliable switching of the perpendicular magnetization in spintronic devices, such as magnetic random‐access memory or spin logic devices. To apply SOT technology to practical devices with low power consumption, it is necessary reduce current. this end, most research date area has focused on improving charge‐to‐spin conversion efficiency heavy metal/ferromagnet structures. In study, reported that current significantly reduced by modulating...