Article
Chemistry, Physical
Maciej J. Szary, Semir El-Ahmar, Tymoteusz Ciuk
Summary: This study investigates the effects of partial H termination on the structural and electronic properties of graphene, suggesting that even with incomplete termination, QFS graphene can still benefit from its intrinsic properties.
APPLIED SURFACE SCIENCE
(2021)
Article
Chemistry, Physical
Yong Han, Marek Kolmer, Michael C. Tringides, James W. Evans
Summary: SiC-supported graphene intercalated by a two-dimensional Pb monolayer is a promising platform for spintronic applications. The thermodynamic stability of this structure has been confirmed in recent experiments. However, the details of intercalated phases, location of atoms, thermodynamic preference, and intercalation pathways are still not fully understood. In this study, extensive density functional theory calculations were conducted to investigate the thermodynamics and kinetics of Pb intercalation on graphene/SiC(0001). The results suggest that intercalation of complete Pb layers in the gallery is strongly favored over other configurations, and more complex intercalation pathways are involved.
Article
Chemistry, Physical
K. Idczak, E. Wachowicz
Summary: This study demonstrates that intercalated gadolinium atoms can significantly affect the electronic properties of graphene and the buffer layer, and temperature-induced intercalation can cause the buffer layer to decouple and transform into a new graphene layer.
APPLIED SURFACE SCIENCE
(2023)
Review
Chemistry, Multidisciplinary
Ivan Shtepliuk, Filippo Giannazzo, Rositsa Yakimova
Summary: The growth of materials on a dangling-bond-free interface like graphene requires additional surface pre-treatment steps, but epitaxial graphene on SiC might offer better conditions. The study focuses on understanding the growth mechanisms through magnetron sputtering, electrodeposition, and atomic layer deposition, with the hope of contributing to the development of new electronic devices.
APPLIED SCIENCES-BASEL
(2021)
Article
Nanoscience & Nanotechnology
Gabriela Copetti, Eduardo H. Nunes, Tais O. Feijo, Lauren A. Galves, Martin Heilmann, Gabriel Soares, J. Marcelo J. Lopes, Claudio Radtke
Summary: Incorporation of chlorine into graphene nanoribbons can increase compressive uniaxial strain, serving as a promising method for tuning the band gap of GNRs.
Article
Materials Science, Multidisciplinary
You-Ron Lin, Susanne Wolff, Philip Schaedlich, Mark Hutter, Serguei Soubatch, Tien-Lin Lee, F. Stefan Tautz, Thomas Seyller, Christian Kumpf, Francois C. Bocquet
Summary: The structure of quasifreestanding monolayer graphene obtained by intercalation of antimony under the reconstructed graphitized SiC surface has been investigated using x-ray and electron microscopy techniques. The results show that the antimony intercalation decouples the graphene layer from the substrate effectively, and the distance between them is similar to the van der Waals bonding distance between carbon and antimony. The antimony intercalation layer is monoatomic, flat, and located close to the substrate, consistent with it being on top of the uppermost silicon atoms of the SiC bulk.
Article
Materials Science, Multidisciplinary
A. A. Rybkina, S. O. Filnov, A. Tarasov, D. Danilov, M. Likholetova, V. Yu Voroshnin, D. A. Pudikov, D. A. Glazkova, A. Eryzhenkov, I. A. Eliseyev, V. Yu Davydov, A. M. Shikin, A. G. Rybkin
Summary: The electronic and crystal structure of zero-layer graphene grown on 6H-SiC(0001) is modified after Co intercalation, transforming into a graphene monolayer with CoSi/CoSi2 structure formed between graphene and SiC substrate. The magnetic properties show ferromagnetic behavior with an open hysteresis loop, and the Dirac cone characteristic of quasi-freestanding graphene is observed.
Article
Chemistry, Physical
Yann Girard, Sarah Benbouabdellah, Outhmane Chahib, Cyril Chacon, Amandine Bellec, Vincent Repain, Jerome Lagoute, Yannick J. Dappe, Cesar Gonzalez, Wei-Bin Su
Summary: The coupling of graphene with cobalt allows for technological advances in spintronics. The study focuses on cobalt intercalation between graphene and a buffer layer, which results in cobalt islands covered by graphene. These islands exhibit distinct shapes and properties, including small atomic islands and flat cobalt nanodots encapsulated by graphene.
Article
Nanoscience & Nanotechnology
P. D. Bentley, T. W. Bird, A. P. J. Graham, O. Fossberg, S. P. Tear, A. Pratt
Summary: Activation of the carbon buffer layer on SiC substrates using elements with high magnetic moments may lead to novel spintronic devices. Intercalation of Er underneath the buffer layer at high temperatures results in the formation of quasi-free-standing graphene, indicating potential applications in spintronics. Further annealing leads to surface graphitization without desorption of Er atoms.
Article
Physics, Applied
Ryotaro Sakakibara, Jianfeng Bao, Keisuke Yuhara, Keita Matsuda, Tomo-o Terasawa, Michiko Kusunoki, Wataru Norimatsu
Summary: We have discovered a step unbunching phenomenon that is the opposite of the step bunching phenomenon. When a 4H-SiC (0001) surface is annealed at a high temperature, steps bunch up due to different velocities of step motion, resulting in steps taller than several nanometers. However, we found that these bunched steps can be unbunched into lower height steps when subsequently annealed at lower temperatures. This competition between energetics and kinetics can explain the underlying mechanism. This finding provides a new method for surface smoothing of SiC using hydrogen etching and has potential implications for SiC power devices and two-dimensional material growth techniques.
APPLIED PHYSICS LETTERS
(2023)
Article
Materials Science, Multidisciplinary
Kohei Fukuma, Anton Visikovskiy, Takushi Iimori, Toshio Miyamachi, Fumio Komori, Satoru Tanaka
Summary: Thermal decomposition of vicinal 6H-SiC(0001) surfaces with miscut angles toward the [1 (1) over bar 00] direction leads to the formation of pairs of (0001) macroterraces and (1 (1) over bar 0n) macrofacets covered with graphene. The graphene forms a (6 root 3 x 6 root 3) buffer layer on the macroterraces and generates a pseudographene nanoribbon (pseudo-GNR) array on the macrofacets.
PHYSICAL REVIEW MATERIALS
(2022)
Article
Chemistry, Physical
Filippo Fabbri, Manuela Scarselli, Naveen Shetty, Sergey Kubatkin, Samuel Lara-Avila, Mathieu Abel, Isabelle Berbezier, Holger Vach, Matteo Salvato, Maurizio De Crescenzi, Paola Castrucci
Summary: Epitaxial graphene has been proven to be an excellent substrate for synthesizing two-dimensional materials. Silicene, a highly anticipated material, has been successfully grown on a slightly defective epitaxial graphene network, opening possibilities for controlled intercalation of silicon atoms and future nanotechnology applications.
SURFACES AND INTERFACES
(2022)
Article
Materials Science, Coatings & Films
Yong Han, James W. Evans, Michael C. Tringides
Summary: We analyze the adsorption and intercalation processes of hydrogen on a graphene surface on SiC through first-principles calculations. Our results show that intercalation between the top-layer and buffer-layer graphene is thermodynamically more favorable than adsorption on the top-layer graphene. We also calculate the energy barriers for hydrogen diffusion on and under the graphene layer and assess the penetration capability of hydrogen atoms on the graphene terrace.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2022)
Article
Nanoscience & Nanotechnology
T. Ciuk, L. Ciura, P. P. Michalowski, J. Jagiello, A. Dobrowolski, K. Pietak, D. Kalita, M. Wzorek, R. Budzich, D. Czolak, A. Kolek
Summary: This report introduces a novel method based on low-frequency noise analysis for evaluating the quality and pattern of inhomogeneity in intentionally-aged Hall effect sensors. By comparing the measured noise with the calculated noise for a homogeneous sensor, we speculate about the presence of unintentional contamination in the active regions of the sensors. Through in-depth structural characterization, we discover that the graphene's characteristics and interface make it susceptible to uncontrolled contamination, leading to blistering of the material.
PHYSICA E-LOW-DIMENSIONAL SYSTEMS & NANOSTRUCTURES
(2022)
Article
Materials Science, Coatings & Films
Hsueh- Chen, Kun-An Chiu, Jing-Feng Lin, Kuan-Yu Lin, Wei-Chia Chen, Ping-Hsun Wu, Cheng-Jung Ko, Li Chang, Chun-Hua Chen
Summary: Epitaxial TiN film has been successfully grown on a semi-insulating single crystal SiC substrate. The effects of growth temperature and nitrogen flow ratio on film quality and growth rate were investigated, revealing that increasing the nitrogen flow ratio improves film quality but decreases growth rate.
SURFACE & COATINGS TECHNOLOGY
(2022)
Article
Mechanics
A. D. Lai, J. F. Jia, J. L. Qu, J. Y. Wang, J. B. Sun, Z. H. Zhou, X. S. Xu, C. W. Lim
Summary: This study investigates the influence of local thinning thickness defects on the buckling of cylindrical shells. A static buckling model is established based on the Hamiltonian system, and the complete symplectic eigensolutions are superimposed to derive the buckling modes of the cylindrical shell with defects. The influence of different defect shapes on the shell's buckling is analyzed by constraining the defect volume, and it is concluded that defects of exponential function are more harmful.
MECHANICS BASED DESIGN OF STRUCTURES AND MACHINES
(2023)
Article
Chemistry, Physical
Sunghun Lee, Sanghyun Ji, Jinsu Kim, Do Duc Cuong, Sonny H. Rhim, Soon Cheol Hong, Yun Chang Park, Young Haeng Lee, Dae Keun Park, Takeshi Toyama, Jiyeong Gu, Myung-Hwa Jung
Summary: The discovery of high-temperature ferromagnetism in beta-Ag2Se topological semimetal, composed of non-magnetic constituents, opens up a significant new direction in material engineering for spintronic applications.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Materials Science, Multidisciplinary
Qurat-ul-Ain, Soon Cheol Hong, S. H. Rhim
Summary: A theoretical study on spin reorientation transition (SRT) was conducted, presenting a phenomenological model that considers the magnetic energy as a sum of various contributions. Analytical solutions revealed the existence of critical strain resulting from the interactions between these contributions. Numerical estimates for thin FePt and Fe60Co40 films showed experimentally accessible critical strain of 2%, attributed to the large magnetoelastic coefficient and optimal saturation magnetization achievable in these films.
JOURNAL OF MAGNETICS
(2021)
Article
Materials Science, Multidisciplinary
Gyu Won Kim, Do Duc Cuong, Yong Jin Kim, In Ho Cha, Taehyun Kim, Min Hyeok Lee, OukJae Lee, Hionsuck Baik, Soon Cheol Hong, Sonny H. Rhim, Young Keun Kim
Summary: The study introduces W-Ta and W-V alloy layers to enhance spin-orbit torque efficiency, with experimental results confirming a 40% improvement in SOT switching efficiency with W-V alloy. Through a combination of theory and experiment, an optimized heterostructure is found to boost torque-based switching efficiency by 40%.
NPG ASIA MATERIALS
(2021)
Article
Chemistry, Physical
Woo Seung Ham, Abdul-Muizz Pradipto, Kay Yakushiji, Kwangsu Kim, Sonny H. Rhim, Kohji Nakamura, Yoichi Shiota, Sanghoon Kim, Teruo Ono
Summary: Dzyaloshinskii-Moriya interaction (DMI) is considered a crucial energy for specific chiral textures like magnetic skyrmions. The research mainly focuses on heavy metal/ferromagnet bilayer systems due to the absence of structural inversion symmetry and exchange energy with spin-orbit coupling. A recent study showed the formation of asymmetric bands in superlattices due to inversion symmetry breaking in stacking order, highlighting the role of bulk-like contribution and strong spin-orbit coupling affecting the bands.
NPJ COMPUTATIONAL MATERIALS
(2021)
Article
Materials Science, Multidisciplinary
T. Thuy Hoang, S. H. Rhim, S. C. Hong
Summary: This paper presents a systematic density functional study on alkali-metal-based half-Heusler compounds, revealing that most ACrZ compounds have a wide band gap and stable half-metallicity. The compounds LiCrZ and NaCrZ (Z = As, Sb) are proposed as promising candidates for spintronics applications, due to their stability, surface and strain tolerance, and good lattice mismatch with zinc-blende semiconductors.
PHYSICAL REVIEW MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Sanghoon Kim, Sachin Pathak, Sonny H. Rhim, Jongin Cha, Soyoung Jekal, Soon Cheol Hong, Hyun Hwi Lee, Sung-Hun Park, Han-Koo Lee, Jae-Hoon Park, Soogil Lee, Hans-Georg Steinruck, Apurva Mehta, Shan X. Wang, Jongill Hong
Summary: This study demonstrates the achievement of inversion asymmetry and unusual strain at interfaces in [Co/Pd] superlattices through low-energy proton irradiation and selective removal of oxygen. The results highlight the importance of establishing both giant orbital anisotropy and strong spin-orbit coupling at the interface for exploring spintronic devices with new functionalities.
Article
Materials Science, Multidisciplinary
Thi H. Ho, D. Odkhuu, S. H. Rhim, S. C. Hong
Summary: In this study, density functional calculations were used to investigate the magnetocrystalline anisotropy (MCA) of hcp and fcc Co films. The results reveal that symmetry, thickness, and surface have significant effects on the MCA of the films. The MCA energy of Co films is greatly enhanced compared to bulk, and thickness-dependent oscillations in MCA were observed.
CURRENT APPLIED PHYSICS
(2022)
Article
Materials Science, Multidisciplinary
T. Thuy Hoang, S. H. Rhim, S. C. Hong
Summary: In this study, the half-metallicity and electronic structure of the LiCrSb/InSb hybrid system are investigated using first-principles calculations. The research reveals that the half-metallicity at the interface is well retained, and the system prefers magnetization parallel to the plane.
JOURNAL OF MAGNETICS
(2022)
Article
Chemistry, Physical
Taehyun Kim, Quynh Anh T. Nguyen, Gyu Won Kim, Min Hyeok Lee, Seok In Yoon, Sonny H. Rhim, Young Keun Kim
Summary: Spin-orbit torque (SOT) based magnetization switching is a current area of interest, and we propose a W-Si alloy as a potential spin current-generating layer in nonvolatile embedded memory and logic devices. Experimental results confirm the required properties of the proposed W-Si/CoFeB heterostructures.
APPLIED SURFACE SCIENCE
(2023)
Article
Materials Science, Multidisciplinary
Thi H. Ho, S. H. Rhim, S. C. Hong
Summary: This study investigates the magnetism of Pd(111) films using first-principles density functional calculations. The results show that a ferromagnetic state is more stable than a paramagnetic state at around 2.5 monolayers thick. The observation of a nesting wave vector and periodic crossing of quantum well states on the Fermi level helps understand the formation of ferromagnetism in the Pd(111) films. The study also finds that tensile strain can enhance the ferromagnetism, and the stability of the film is affected by its thickness.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
Quynh Anh T. Nguyen, Thi H. Ho, Myung-Hwa Jung, Sonny H. Rhim
Summary: The effect of Co substitution on Mn3Ga was examined using first-principles study, revealing that Mn3Ga prefers tetragonal phase when Co concentration (x) is less than or equal to 0.5, and cubic phase when x is greater than or equal to 0.5. The ferrimagnetic property remains robust regardless of x in both phases.
CURRENT APPLIED PHYSICS
(2023)
Article
Nanoscience & Nanotechnology
Kai Liu, Jian Zheng, Yating Sha, Bosai Lyu, Fengping Li, Youngju Park, Yulu Ren, Kenji Watanabe, Takashi Taniguchi, Jinfeng Jia, Weidong Luo, Zhiwen Shi, Jeil Jung, Guorui Chen
Summary: Interactions among charge carriers in graphene can lead to the spontaneous breaking of multiple degeneracies. In this study, the stacking orders of tetralayer graphene devices were determined using near-field infrared imaging. Through quantum transport measurements, a range of spontaneous broken-symmetry states and their transitions were observed, which could be finely tuned by carrier density and electric displacement field. These findings highlight the potential of multilayer graphene as a platform for investigating broken symmetries.
NATURE NANOTECHNOLOGY
(2023)
Article
Physics, Multidisciplinary
Minkyu Park, Guihyun Han, S. H. Rhim
Summary: Traditionally, it was believed that the anomalous Hall effect (AHE) could only be observed in ferromagnets. However, this study shows that any magnetic material can exhibit AHE due to the broken time-reversal symmetry. By using symmetry arguments and first-principles calculations, the researchers present a nontrivial AHE on the compensated ferrimagnet Mn3Al. The nature of Berry curvature responsible for the intrinsic origin of AHE is further identified using group theory, and the overlooked contributions around X' are revealed by showing the global behaviors of Berry curvatures over the whole Brillouin zone.
PHYSICAL REVIEW RESEARCH
(2022)
Article
Materials Science, Multidisciplinary
Nam-Hui Kim, Qurat-ul-ain, Joonwoo Kim, Eunchong Baek, June-Seo Kim, Hyeon-Jong Park, Hiroshi Kohno, Kyung-Jin Lee, Sonny H. Rhim, Hyun-Woo Lee, Chun-Yeol You
Summary: The interfacial perpendicular magnetic anisotropy (iPMA) and interfacial Dzyaloshinskii-Moriya interaction (iDMI) in ferromagnet/heavy metal bilayers exhibit similar Slater-Pauling-like dependence on the FM variation as the saturation magnetization (MS) does. This finding suggests that the density of states structure important for the Slater-Pauling dependence is crucial for iPMA and iDMI as well, providing a useful method to engineer chiral magnetic textures.