A5050951421- Magnetic properties of thin films
- Quantum and electron transport phenomena
- Physics of Superconductivity and Magnetism
- Magnetic and transport properties of perovskites and related materials
- Magnetic Properties and Applications
- Semiconductor materials and devices
- ZnO doping and properties
- Semiconductor materials and interfaces
- Iron-based superconductors research
- Topological Materials and Phenomena
- Advanced Condensed Matter Physics
- Advancements in Semiconductor Devices and Circuit Design
- Magneto-Optical Properties and Applications
- Surface and Thin Film Phenomena
- Theoretical and Computational Physics
- Transition Metal Oxide Nanomaterials
- Magnetic Field Sensors Techniques
- Electronic and Structural Properties of Oxides
- Graphene research and applications
- Microstructure and Mechanical Properties of Steels
- 2D Materials and Applications
- Silicon Carbide Semiconductor Technologies
- Organic and Molecular Conductors Research
- Rare-earth and actinide compounds
- Ultrasound Imaging and Elastography
Chung-Ang University
2024
Max Planck Institute of Microstructure Physics
2020-2023
University of Cambridge
2018-2020
Korea Advanced Institute of Science and Technology
1994-2017
Korea Institute of Science and Technology
2017
National Institute of Advanced Industrial Science and Technology
2013-2015
358 (Finland)
2011
Oxygen defects and their atomic arrangements play a significant role in the physical properties of many transition metal oxides. The exemplary perovskite SrCoO3-δ (P-SCO) is metallic ferromagnetic. However, its daughter phase, brownmillerite SrCoO2.5 (BM-SCO), insulating an antiferromagnet. Moreover, BM-SCO exhibits oxygen vacancy channels (OVCs) that thin films can be oriented either horizontally (H-SCO) or vertically (V-SCO) to film's surface. To date, orientation these OVCs has been...
Non-reciprocal electronic transport in a spatially homogeneous system arises from the simultaneous breaking of inversion and time-reversal symmetries. Superconducting Josephson diodes, key ingredient for future non-dissipative quantum devices, have recently been realized. Only few examples vertical superconducting diode effect reported its mechanism, especially whether intrinsic or extrinsic, remains elusive. Here we demonstrate substantial supercurrent non-reciprocity van der Waals junction...
Sub-5nm all-around gate FinFETs with 3nm fin width were fabricated for the first time. The n-channel FinFET of sub-5nm 1.4nm HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2 </sub> shows an I xmlns:xlink="http://www.w3.org/1999/xlink">Dsat</sub> 497μA/μm at V xmlns:xlink="http://www.w3.org/1999/xlink">G</sub> =V xmlns:xlink="http://www.w3.org/1999/xlink">D</sub> =1.0V. Characteristics transistor are verified by using 3-D simulations as well...
We first report the all-electrical spin injection and detection in CoFe/MgO/moderately doped n-Ge contact at room temperature (RT), employing threeterminal Hanle measurements. A sizable signal of ~170 k{\Omega} {\mu}m^2 has been observed RT, analysis using a single-step tunneling model gives lifetime ~120 ps diffusion length ~683 nm Ge. The shows asymmetric bias dependences which are strongly related to asymmetry process.
We investigate the influence of Meissner screening and trapped magnetic flux on magnetization dynamics for a Ni80Fe20 film sandwiched between two thick Nb layers (100 nm) using broadband (5-20 GHz) ferromagnetic resonance (FMR) spectroscopy. Below superconducting transition Tc Nb, significant zero-frequency line broadening (5-6 mT) DC field shift (50 to low are both observed if thickness is comparable London penetration depth films (>= 100 nm). attribute peculiar behaviors increased...
The proximity-coupling of a chiral non-collinear antiferromagnet (AFM)1-5 with singlet superconductor allows spin-unpolarized Cooper pairs to be converted into spin-polarized triplet pairs6-8, thereby enabling non-dissipative, long-range spin correlations9-14. mechanism this conversion derives from fictitious magnetic fields that are created by non-zero Berry phase15 in AFMs atomic-scale arrangements1-5. Here we report long-ranged lateral Josephson supercurrents through an epitaxial thin...
We report the electrical spin accumulation with enhanced bias voltage dependence in n-type Si, employing a crystalline CoFe/MgO tunnel contact. A sizable signal of ∼4.8 kΩμm2, lifetime ∼155 ps, and diffusion length ∼220 nm were obtained at 300 K. The this system show consistent behavior temperature variation irrespective voltage. Notably, exhibits nearly symmetric respect to polarity, which is ascribed improved polarization.
Spin-triplet supercurrent spin valves are of practical importance for the realization superconducting spintronic logic circuits. In ferromagnetic Josephson junctions, magnetic-field-controlled non-collinearity between spin-mixer and spin-rotator magnetizations switches spin-polarized triplet supercurrents on off. Here we report an antiferromagnetic equivalent such spin-triplet in chiral junctions as well a direct-current quantum interference device. We employ topological antiferromagnet...
Recent progress in superconducting spintronics has highlighted the potential of superconductors (SCs) low-energy computing technologies. Most studies quasiparticle spin transport SCs have relied on dc measurements, but this one utilizes inverse spin-Hall effect induced by pumping to investigate spin-orbit coupling and Nb, standard material for applications. The authors not only provide reliable values angle spin-diffusion length also suggest a better device geometry electrical detection...
A recent ferromagnetic resonance study [Jeon et al., Nat. Mater. 17, 499 (2018)] has reported that spin pumping into a singlet superconductor (Nb) can be greatly enhanced over the normal state when Nb is coupled to large spin-orbit-coupling (SOC) sink such as Pt. This behavior been explained in terms of generation spin-polarized triplet supercurrents via SOC at Nb/Pt interface, acting conjunction with nonlocally induced magnetic exchange field. Here we report effect adding ferromagnet (Fe)...
We present measurements of ferromagnetic-resonance - driven spin pumping and inverse spin-Hall effect in NbN/Y3Fe5O12 (YIG) bilayers. A clear enhancement the (effective) Gilbert damping constant thin-film YIG was observed due to presence NbN sink. By varying thickness employing spin-diffusion theory, we have estimated room temperature values diffusion length Hall angle be 14 nm -1.1 10-2, respectively. Furthermore, determined spin-mixing conductance NbN/YIG interface 10 nm-2. The...
Although recent experiments and theories have shown a variety of exotic transport properties non-equilibrium quasiparticles (QPs) in superconductor (SC)-based devices with either Zeeman or exchange spin-splitting, how QP interplays magnon spin currents remains elusive. Here, using non-local spin-transport where singlet SC (Nb) on top ferrimagnetic insulator (Y3Fe5O12) serves as detector, we demonstrate that the conversion efficiency to charge via inverse spin-Hall effect (iSHE) such an...
Spin-transport in superconductors is a subject of fundamental and technical importance with the potential for applications superconducting-based cryogenic memory logic. Research this area rapidly intensifying recent discoveries establishing field superconducting spintronics. In perspective, we provide an overview experimental state-of-the-art particular focus on local nonlocal spin-transport propose device schemes to demonstrate viability spin-based devices.
We report Abrikosov vortex nucleation in Pt/Nb/Ni80Fe20/Nb/Pt proximity-coupled structures under oblique ferromagnetic resonance (FMR) that turns out to be detrimental superconducting spin pumping. By measuring an out-of-plane field-angle {\theta}H dependence and comparison with Pt-absent control samples, we show as increases, the degree of enhancement (suppression) pumping efficiency state for Pt-present (Pt-absent) sample diminishes it reverts normal value at = 90{\deg}. This can explained...
Recent ferromagnetic resonance experiments and theory of Pt/Nb/Ni8Fe2 proximity-coupled structures strongly suggest that spin-orbit coupling (SOC) in Pt conjunction with a magnetic exchange field Ni8Fe2 are the essential ingredients to generate pure spin supercurrent channel Nb. Here, by substituting for perpendicularly magnetized Pt/Co/Pt spin-sink, we able demonstrate role SOC, show pumping efficiency across Nb is tunable controlling magnetization direction Co. By inserting Cu spacer weak...
We report the epitaxial growth of MgO and CoFe/MgO on Ge (001) substrates using molecular beam epitaxy. It was found that a film could be realized at low temperature 125 ± 5 °C matches with cell ratio 21/2:1, which renders rotated by 45° relative to Ge. In-situ ex-situ structural characterizations reveal crystal bcc in-plane crystallographic relationship CoFe(001)[100]∥MgO(001)[110]∥Ge(001)[100], exhibiting sharp interfaces in matching planes. The saturation magnetization sample is 1430 20...
We investigated the correlation between ferromagnetism and electric resistivity of Mo-doped (3–10 at. %) In2O3 films. find that saturation magnetization increases with Mo concentration until it reaches its maximum at 7 % doping (7.1 emu/cm3), after which rapidly decreases upon higher concentration. Interestingly, reveals opposite behavior concentration, showing a minimum value doping. According to temperature-dependent Hall effect measurements, we samples show metallic electron Notably,...
We have investigated the temperature and bias dependence of Hanle effect in a composite n-type Ge system consisting heavily doped surface layer moderately substrate, using three-terminal measurements. A large spin signal ∼5.1 kΩμm2 lifetime ∼105 ps are obtained at 300 K. The signal, lifetime, their asymmetries with respect to polarity been measured over range from 5 K Intriguingly, an inverted effect, indicating sign inversion polarization Ge, is observed low temperature.
Understanding the interplay between spin and heat is a fundamental intriguing subject. Here we report thermal injection accumulation in CoFe/MgO/n-type Ge contacts with an asymmetry of tunnel polarization. Using local heating electrodes by laser beam or electrical current, thermally-induced observed for both polarities temperature gradient across contact. We observe that magnitude thermally injected signal scales linearly power its sign reversed as invert gradient. A large Hanle...
We report a breakdown of Barkhausen critical-scaling behavior in NiO/Fe films with increasing domain-wall pinning by means Kerr microscope capable direct domain observation. The time-resolved images the revealed that jump size is generally decreased NiO thickness, showing an enhanced effect. Interestingly enough, power-law scaling distribution gradually disappears as walls Fe layer increased. This ascribed to fact magnetization reversal mechanism changed from avalanche dominant mode creep mode.
We report the proper resistance-area products in single crystalline bcc CoFe/MgO tunnel contact on nondegenerate n-Ge desirable for efficient spin injection and detection at room temperature. The electric properties of CoFe(5.0 nm)/MgO/n-Ge(001) contacts with an ultrathin MgO thickness 1.5, 2.0, 2.5 nm have been investigated by I-V-T C-V measurements. Interestingly, 2.0-nm exhibits Ohmic behavior RA 5.20×10−6/1.04×10−5 Ω m2 ±0.25 V, satisfying theoretical conditions required significant...
We have investigated the electrical Hanle effect with magnetic fields applied at an oblique angle (\ensuremath{\theta}) to spin direction [the (OHE)] in CoFe/MgO/semiconductor (SC) contacts by employing a three-terminal measurement scheme. The signals obtained CoFe/MgO/Si and CoFe/MgO/Ge show clearly different line shapes depending on lifetime of host SC. Notably, moderate fields, asymptotic values (in both contacts) are consistently reduced factor ${\mathrm{cos}}^{2}(\ensuremath{\theta})$...