Article
Physics, Applied
N. Saenphum, J. Chureemart, R. F. L. Evans, R. W. Chantrell, P. Chureemart
Summary: This paper explores the use of GMR heads to improve reader performance by studying the effect of material properties and layer thickness on RA and MR ratio. It is found that using a Co2FeAl Heusler alloy electrode in the spin valve leads to better performance compared to conventional ferromagnetic materials. Additionally, the study considers the thickness dependence of Delta RA and its relationship with the spin diffusion length of nonmagnetic materials.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2021)
Article
Engineering, Electrical & Electronic
William Frost, Marjan Samiepour, Atsufumi Hirohata
Summary: Half-metallic Heusler alloys with in-plane magnetic anisotropy can be converted to perpendicular with bcc seed layers like V and W, but these layers have shown limited GMR ratios in spin-valve structures due to high resistivity. Nonmagnetic overlayers, particularly Ag layers, have been found to effectively maintain the perpendicular anisotropy and improve GMR performance in Heusler-alloy films.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2022)
Article
Physics, Applied
Kresna B. Fathoni, Yuya Sakuraba, Yoshio Miura, Taisuke Sasaki, Tomoya Nakatani, Kazuhiro Hono
Summary: The study indicates that in order to enhance the magnetoresistance ratio in CIP-GMR using half-metallic materials, it is crucial to match the resistivity between the ferromagnetic layers and the nonmagnetic layer, in addition to considering the high electronic band matching as a key factor to achieve high MR ratio in CIP-GMR devices.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2022)
Article
Physics, Applied
Yu Feng, Haonan Ding, Xiaohua Li, Bo Wu, Hong Chen
Summary: A highly lattice-matched all-Heusler-alloy magnetic tunnel junction (MTJ) with a CoFeTiSi electrode and a Fe2TiSi barrier is proposed. The MTJ exhibits a high equilibrium tunnel magnetoresistance (TMR) ratio and has two transport channels, with channel I playing a dominant role. The non-equilibrium spin transport analysis shows that the MTJ can produce a highly polarized transport current and has good stability.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Physics, Applied
Fen Xue, Shy-Jay Lin, D. C. Mahendra, Chong Bi, Xiang Li, Wilman Tsai, Shan X. Wang
Summary: This study reports a novel high-efficiency spin Hall material, achieved through the design of a multilayer structure that combines low resistivity and tunable spin Hall effect. Various detection methods were used to study the mechanism and efficiency of SOT in the [Pt/Co](n) multilayer, revealing important spin reorientation transition states.
APPLIED PHYSICS LETTERS
(2021)
Article
Physics, Condensed Matter
Lei Zhang, Binyuan Zhang, Liwei Jiang, Yisong Zheng
Summary: In this study, a high-performance "All-Heusler" spin valve is constructed by replacing atoms in the electrode material. The most stable interface is determined using first-principles calculations, and it is found that the half-metallicity at the interface is maintained. The spin valve exhibits significant theoretical magnetoresistance.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2022)
Article
Nanoscience & Nanotechnology
B. Kaiser, J. Ramberger, J. D. Watts, J. Dewey, Y. Zhang, C. Leighton
Summary: In order to increase the spin signal, we integrated high-spin-polarization Co-Fe alloy ferromagnetic injectors and detectors into Al-based non-local spin valves. Smooth, polycrystalline (110-textured), solid-solution body-centered-cubic Co75Fe25 films were generated by room-temperature deposition on amorphous substrates from an alloy target, characterized by various techniques. Integration into transparent-interface Al non-local spin valves resulted in a similar to 5-fold enhancement of the spin signal relative to Co, with temperature-independent current spin polarizations exceeding 60%. Comparisons with prior literature show that Co-Fe alloys offer a facile route to higher spin polarization and spin signals in non-local spin valves, with minimal barrier to adoption.
Article
Nanoscience & Nanotechnology
Ryo Toyama, Varun K. Kushwaha, Taisuke T. Sasaki, Yuma Iwasaki, Tomoya Nakatani, Yuya Sakuraba
Summary: In this study, a high-throughput compositional optimization method for high spin polarization in Co-2(Mn, Fe)Ge Heusler alloys is demonstrated. By combining composition-spread films and anisotropic magnetoresistance (AMR) measurement, the composition dependence of AMR and spin polarization is investigated. The results show that the highest spin polarization can be achieved at specific composition ratios.
Article
Physics, Multidisciplinary
Po-Hsun Wu, Danru Qu, Yen-Chang Tu, Yin-Ze Lin, C. L. Chein, Ssu-Yen Huang
Summary: This study demonstrates the interplay of pure spin current, spin-polarized current, and spin fluctuation in 3d NixCu1-x. By exploiting the interaction of spin current with spin fluctuation in suitable Ni-Cu alloys, an unprecedentedly high spin Hall angle and spin-dependent thermal transport are achieved, which are of great significance for spintronic applications.
PHYSICAL REVIEW LETTERS
(2022)
Article
Engineering, Electrical & Electronic
Sajib Biswas, Saumen Chaudhuri, Niladri Kander, Srimanta Mitra, Suman Guchhait, Amal Kumar Das
Summary: The performance of spintronic devices is highly dependent on spin polarization, as shown in calculations and experiments on Co2FeSi alloys. Both L2(1)-ordered and B2-disordered structures exhibit decreased spin polarization but increased total magnetic moment. Additionally, the accumulation of spin-polarized carriers in p-type silicon from Co2FeSi film was demonstrated, along with a prominent spin-valve effect at low temperature in the device.
ACS APPLIED ELECTRONIC MATERIALS
(2021)
Article
Physics, Multidisciplinary
B. Stoddart-Stones, X. Montiel, M. G. Blamire, J. W. A. Robinson
Summary: Superconducting spintronics aims to enhance the performance of spintronics-based devices by utilizing the interaction between magnetic order and superconductivity. In this study, the authors experimentally investigate a superconducting spin valve and observe a crossover from giant magnetoresistance to the superconducting spin-valve effect as the thickness of the material changes.
COMMUNICATIONS PHYSICS
(2022)
Article
Physics, Applied
Xinlu Li, Yurong Su, Meng Zhu, Fanxing Zheng, Peina Zhang, Jia Zhang, Jing-Tao Lu
Summary: The study reveals a vdW CPP GMR with significant advantages, including perpendicular magnetic anisotropy, large GMR, low RA, and sizable AMR, which mainly originate from the bulk electronic structure properties of Fe3GeTe2. This work may stimulate future experimental explorations and have potential applications in spintronic devices.
PHYSICAL REVIEW APPLIED
(2021)
Article
Materials Science, Multidisciplinary
Ivan Kurniawan, Kenji Nawa, Keisuke Masuda, Yoshio Miura, Kazuhiro Hono
Summary: The study found that modulation of the Fermi level position in half-metallic alloys can improve the temperature dependence of spin polarization, but alloys rich in Co or Fe show lower spin polarization compared to stoichiometric alloys.
Article
Materials Science, Multidisciplinary
Xueli Yang, Ankang Guo, Lidan Guo, Yunqi Liu, Xiangnan Sun, Yunlong Guo
Summary: This article summarizes the basic operating principle and mechanism of organic spin valves (OSVs) and discusses the importance of accomplishing room-temperature spin transport, FM electrode selection, and spinterface. The state-of-the-art progress of organic semiconductors (OSCs) with room-temperature spin transport in spin valves is reviewed. Furthermore, the effects of carrier mobility and spin relaxation time on the spin diffusion length are systematically analyzed. A feasible perspective for improving the spin transport properties of OSCs is presented.
ACS MATERIALS LETTERS
(2022)
Article
Materials Science, Multidisciplinary
Kresna B. Fathoni, Zehao Li, Tomoya Nakatani, Yuya Sakuraba, Taisuke Sasaki, Kazuhiro Hono
Summary: The MR ratio of CoFe/bcc-Cu/CoFe CIP-GMR devices grown on Si(0 0 1) substrate is slightly lower than that grown on MgO(0 0 1) substrate due to the presence of fcc phase of Cu.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
Z. X. Chen, Y. Sakuraba, K. Masuda, X. D. Xu, L. S. R. Kumara, H. Tajiri, Y. Kotani, V Kushwaha, A. Perumal, K. Hono
Summary: In this study, the transport properties, microstructure, and atomic order of CoFeCrAl (CFCA) thin films were systematically analyzed. It was predicted that CFCA is a spin-gapless semiconductor (SGS), but experimental results revealed that one of the films lost this property after annealing. However, the film still exhibited some transport properties similar to those of a spin-gapless semiconductor.
Article
Physics, Applied
Tomohiro Ichinose, Tatsuya Yamamoto, Jun Uzuhashi, Takayuki Nozaki, Tadakatsu Ohkubo, Kay Yakushiji, Shingo Tamaru, Kazuhiro Hono, Shinji Yuasa
Summary: Thermally robust perpendicular magnetic anisotropy and voltage-controlled magnetic anisotropy effects were achieved in magnetic tunnel junctions with ultrathin CoFeB films by utilizing Ta/Mo layered adhesion structures.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Materials Science, Multidisciplinary
Shin Inagaki, Yan-Cheng Lin, Hisakazu Tanaka, Tomoyuki Koganezawa, Wen-Chang Chen, Tomoya Higashihara
Summary: A novel A-b-(B-co-C)-type terpolymer was synthesized to address the issue of irreversible damage caused by stretching in organic semiconductors for wearable electronic devices. The terpolymer showed high stretchability, stable device performance, and stable bipolar charge trapping.
MATERIALS CHEMISTRY AND PHYSICS
(2022)
Article
Multidisciplinary Sciences
Xin Tang, H. Sepehri-Amin, N. Terada, A. Martin-Cid, I Kurniawan, S. Kobayashi, Y. Kotani, H. Takeya, J. Lai, Y. Matsushita, T. Ohkubo, Y. Miura, T. Nakamura, K. Hono
Summary: The authors demonstrate a series of materials with a large and reversible magnetocaloric effect, suitable for the full temperature range required for hydrogen liquefaction. By eliminating the magneto-structural phase transition, the giant magnetocaloric effect becomes reversible.
NATURE COMMUNICATIONS
(2022)
Review
Nanoscience & Nanotechnology
Shinji Isogami, Yukiko K. Takahashi
Summary: Light elements such as B, C, and N play a crucial role in various functional materials and have attracted considerable attention in recent years. In this article, the evolution and utilization of light elements are reviewed, and their representative applications and characteristics are highlighted. Additionally, the effect of B and C on magnetic structures is discussed, and future strategies for practical material development are proposed.
ADVANCED ELECTRONIC MATERIALS
(2023)
Article
Nanoscience & Nanotechnology
Kazuho Okada, Akinobu Shibata, Taisuke Sasaki, Hisashi Matsumiya, Kazuhiro Hono, Nobuhiro Tsuji
Summary: This study aimed to improve the resistance against hydrogen embrittlement by increasing the concentration of carbon segregated at prior austenite grain boundary (PAGB), XPAGB, in low-carbon martensitic steels. The specimens with and without carbon segregation treatment (Non-seg and Seg specimens, respectively) had similar microstructures, except for higher XPAGB in the Seg specimen. The Seg specimen exhibited higher maximum stress and smaller fraction of intergranular fracture surface under hydrogen-charged conditions, indicating that segregated carbon suppressed hydrogen accumulation and increased cohesive energy of PAGB.
SCRIPTA MATERIALIA
(2023)
Article
Materials Science, Multidisciplinary
Yann Kervella, Jose Maria Andres Castan, Yatzil Alejandra Avalos-Quiroz, Anass Khodr, Quentin Eynaud, Tomoyuki Koganezawa, Noriyuki Yoshimoto, Olivier Margeat, Agnes Rivaton, Antonio J. Riquelme, Valid Mwatati Mwalukuku, Jacques Pecaut, Benjamin Grevin, Christine Videlot-Ackermann, Jorg Ackermann, Renaud Demadrille, Cyril Aumaitre
Summary: We synthesized a star-shape non-fullerene acceptor (NFA) with a D(A)(3) structure based on an aza-triangulene unit as the electron-donating core. The NFA exhibited strong absorption in the visible range and demonstrated good optoelectronic properties in solution and thin films. When combined with PTB7-Th as the electron donor, the NFA achieved a high power conversion efficiency of around 6.3% in inverted solar cells.
JOURNAL OF MATERIALS CHEMISTRY C
(2023)
Article
Microscopy
Sujin Lee, Atsuko Sato, Takehiro Tamaoka, Kunio Yubuta, Mitsunari Auchi, Taisuke Sasaki, Tadakatsu Ohkubo, Kazuhiro Hono, Yasukazu Murakami
Summary: This paper proposes a method using electron holography to provide a phase image of the demagnetization field (H-d) within a thin-foil permanent magnet. The observation of H-d remains challenging because electron holography can only image the magnetic flux density (B), which is a combination of contributions from magnetization (M), stray magnetic field (H-s) outside the specimen, and H-d inside the specimen. The phase map approximating H-d, determined from electron holography observation of a Nd2Fe14B single-crystalline specimen, shows good agreement with micromagnetic theory's prediction. This method can be applied to study the coercivity mechanism of permanent magnets, which is sensitive to the demagnetization field.
Article
Materials Science, Multidisciplinary
Z. Wang, T. T. Sasaki, Y. Une, T. Ohkubo, K. Hono
Summary: Record-breaking high coercivity is achieved in Dy-free sintered magnets by separately diffusing Dy70Cu30 and Pr68Cu32 eutectic alloys. The low Dy content sample exhibits a high coercivity of 2.8 T and an excellent temperature coefficient of coercivity. The unique presence of a uniform Dy-rich shell and enriched Pr near the surface of Nd2Fe14B grains strengthens the anisotropy field, resulting in the high coercivity without alloying Dy to the initial magnet.
Article
Chemistry, Multidisciplinary
Ming-Shui Yao, Ken-ichi Otake, Jiajia Zheng, Masahiko Tsujimoto, Yi-Fan Gu, Lu Zheng, Ping Wang, Shivanna Mohana, Mickaele Bonneau, Tomoyuki Koganezawa, Tetsuo Honma, Hirotaka Ashitani, Shogo Kawaguchi, Yoshiki Kubota, Susumu Kitagawa
Summary: A method of integrating the soft porosity and electrical properties of metal-organic frameworks (MOFs) into a single material is achieved through the design of conductive-on-insulating MOF (cMOF-on-iMOF) heterostructures. The cMOF-on-iMOF heterostructures exhibit enhanced selective sorption of CO2 and flexibility in sensing and electrical shape memory. These properties are attributed to the porous interface formed by the hybridization of both frameworks at the molecular level, as observed through operando synchrotron grazing incidence wide-angle X-ray scattering measurements.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Physical
Z. H. Kautsar, H. Sepehri-Amin, Xin Tang, R. Iguchi, K. Uchida, T. Ohkubo, K. Hono
Summary: The resistivities of anisotropic Nd-Fe-B-based magnets were increased in parallel and perpendicular directions to the c-axis by hot-deforming Nd-Fe-B melt-spun flakes coated with DyF3 through electrophoretic deposition. As a result, the operating temperature under high-frequency AC magnetic field decreased by 20°C due to the reduction of eddy current loss. The formation of a resistive layer composed of NdF3 at the interface of original ribbons in the hot-deformed magnet was observed. The excess Dy diffused into the original ribbon flakes and formed a Dy-rich shell in Nd2Fe14B grains, resulting in a high coercivity.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Microscopy
Jun Uzuhashi, Tadakatsu Ohkubo, Kazuhiro Hono
Summary: Atom probe tomography (APT) is a widely used technique for analyzing the microstructure of alloys and devices. In this study, a method for automatically fabricating the desired tip shape using a script-controlled FIB-SEM system was developed. The effect of intentionally changing the tip shape on APT data was also discussed.
Article
Materials Science, Multidisciplinary
Phillip David Bentley, Songtian Li, Keisuke Masuda, Yoshio Miura, Ye Du, Takaya Mitsui, Kosuke Fujiwara, Yasuhiro Kobayashi, Tengyu Guo, Guoqiang Yu, Chihiro Suzuki, Shunya Yamamoto, Fu Zheng, Yuya Sakuraba, Seiji Sakai
Summary: This study developed ferrimagnetic cubic Heusler compound Mn(2)FexGa (MFG) thin films with large perpendicular magnetic anisotropy (PMA). By growing MFG on a Cr buffer layer, large PMA exceeding 0.75 MJ m(-3) was obtained in stoichiometric Mn2FeGa (x = 1). First-principles calculations demonstrated that Fe's characteristic electronic structure in the X-a-ordered cubic MFG causes a large uniaxial magnetocrystalline anisotropy under the tetragonal strain consistent with experiment. Cubic Mn2FeGa with its small saturation magnetization, large PMA, and possibility of being highly spin polarized is an ideal candidate for spintronic device development.
PHYSICAL REVIEW MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Ryo Toyama, Satoshi Kokado, Keisuke Masuda, Zehao Li, Varun K. Kushwaha, Taisuke T. Sasaki, Loku Singgappulige Rosantha Kumara, Tomoyuki Koganezawa, Hiroo Tajiri, Takahiro Yamazaki, Masato Kotsugi, Yuma Iwasaki, Yuya Sakuraba
Summary: In this paper, the origin of the anisotropic magnetoresistance (AMR) effect in thin films is investigated through experimental observation and theoretical modeling. It is found that the addition of Ir atoms leads to a sign change in the AMR ratio, with the highest negative values observed at high Ir concentrations. The theoretical model confirms that this sign change is due to the B2 ordering phase. These findings provide insights into the AMR origin in heavy-metal-doped ferromagnetic alloys.
PHYSICAL REVIEW MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Q. Eynaud, Y. A. Avalos Quiroz, T. Koganezawa, R. Sato, N. Yoshimoto, O. Margeat, C. M. Ruiz, J. Ackermann, C. Videlot-Ackermann
Summary: For wavelength-selective photodetection or color discrimination, organic photodetectors (OPDs) have advantages such as solution processability, chemical versatility, and functionality. This study demonstrates a bulk-heterojunction (BHJ) organic blend that exhibits a filter-free visible-blind near-infrared light responsive characteristic. The optimized OPD achieves a high-selective spectral response with an external narrowband quantum efficiency of 24.5% and a bandwidth of 42 nm centered at 807 nm.
JOURNAL OF MATERIALS CHEMISTRY C
(2023)
