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
Engineering, Electrical & Electronic
Michihiro Yamada, Takahiro Naito, Kazuaki Sumi, Kentarou Sawano, Kohei Hamaya
Summary: The study investigates the temperature dependence of two-terminal local magnetoresistance effect in Ge-based lateral spin-valve devices with Fe insertion. The significant improvement in local MR signals at low temperatures to room temperature is observed, but the large temperature dependence of the MR ratio remains.
IEEE TRANSACTIONS ON MAGNETICS
(2022)
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
Chemistry, Physical
Yu Feng, Haonan Ding, Bo Wu
Summary: High spin-injection-efficiency (SIE) and thermal spin-filter-effect (SFE) are crucial for the high performance of spintronic and spin caloritronic devices. In this study, we investigate the spin transport properties of a RuCrAs-based spin valve with different atom-terminated interfaces using nonequilibrium Green's function and first-principles calculations. The spin valve with a CrAs-top (or Ru-top) interface structure exhibits a high equilibrium magnetoresistance (MR) ratio, 100% SIE, large MR ratio, and high spin current intensity under bias voltage, making it promising for spintronic applications. The spin valve with the CrAs-top (or CrAs-bri) interface structure shows perfect SFE due to its high spin polarization of temperature-driven currents, making it useful for spin caloritronic devices.
JOURNAL OF CHEMICAL PHYSICS
(2023)
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
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, Ceramics
Pradeep Kumar, Anuj Kumar, Davinder Kaur
Summary: In this study, few-layer molybdenum disulfide (FL-MoS2) was successfully fabricated as a non-magnetic spacer layer in a magnetic tunnel junction (MTJ), exhibiting spin valve effect in the presence of an external magnetic field. Detailed investigation on the thickness and temperature-dependent behavior of tunneling magnetoresistance (TMR) in the MTJ was conducted, providing insights for advanced magnetic device applications using sputtered FL-MoS2 and ferromagnetic shape memory alloy in ultrafast spintronics.
CERAMICS INTERNATIONAL
(2021)
Article
Nanoscience & Nanotechnology
Konstantin V. Larionov, Jose J. Pais Pereda, Songtian Li, Seiji Sakai, Pavel B. Sorokin
Summary: Integrating half-metallic materials and 2D spacers into vertical magnetoresistive spin valves may lead to effective low-power consumption storage and memory technologies. The study investigated magnetic tunnel junctions based on ferromagnetic CFGG Heusler alloy and MoS2 spacers of different thicknesses, demonstrating a large magnetoresistance value. The findings support the development of spintronics devices utilizing half-metallic Heusler alloys and diverse transition metal dichalcogenide family.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Materials Science, Multidisciplinary
Manikandan Gunasekaran, Dhanalakshmi Dhandapani, Manivel Raja Muthuvel
Summary: Organic semiconductors have potential applications in spintronics. In this study, an organic spin valve device using RR-P3HT material was fabricated, and both positive and negative magnetoresistance were observed. The magnetic properties of the device were analyzed using VSM.
ELECTRONIC MATERIALS LETTERS
(2023)
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
Nanoscience & Nanotechnology
Amit Chanda, Deepika Rani, Derick Detellem, Noha Alzahrani, Dario A. Arena, Sarath Witanachchi, Ratnamala Chatterjee, Manh-Huong Phan, Hariharan Srikanth
Summary: This study investigates the temperature-dependent anomalous Nernst effect (ANE) and longitudinal spin Seebeck effect (LSSE) in CoFeCrGa thin films grown on MgO substrates. The results show that the MgO/CoFeCrGa films have high ANE and LSSE coefficients at room temperature, with peaks observed as the temperature increases.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Materials Science, Multidisciplinary
Rudolf Smorka, Pavel Balaz, Michael Thoss, Martin Zonda
Summary: In this study, we investigated the spin dynamics and spin-transfer torque in a spin valve under bias voltage using a hybrid quantum-classical equation of motion approach. We found that the interaction between localized classical magnetic moments and conduction electrons results in a complex effective exchange coupling between the magnetic layers, leading to a deviation of magnetizations from their anisotropy axes even in equilibrium. The introduction of a finite bias voltage triggers spin currents and spin-transfer torques, which further tilt the magnetizations and govern the relaxation processes of the spin dynamics. By analyzing different scenarios of the applied bias voltage, we observed that symmetric and asymmetric voltage drops can cause relaxation times of the spin dynamics to differ by several orders of magnitude at comparable charge currents. In both cases, resonant features were observed, where the relaxation was enhanced whenever the chemical potential of the leads matched the maxima in the density of the states of the spin-valve electrons.
Article
Physics, Applied
Andrei Azovtsev, Nikolay A. Pertsev
Summary: Acoustic excitation is an attractive tool for generating spin dynamics in magnetoelastic materials. In this study, we theoretically describe the magnetization dynamics and spin flow induced by acoustic waves in trilayer structures. Our results show that the acoustic waves cause inhomogeneous magnetization precession, oscillating spin current, and spin accumulation in the spacer.
PHYSICAL REVIEW APPLIED
(2022)
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
Materials Science, Multidisciplinary
Ying Wang, Jiarong Yao, Shuaishuai Ding, Siyu Guo, Dapeng Cui, Xinyue Wang, Shuyuan Yang, Lijuan Zhang, Xinzi Tian, Di Wu, Chao Jin, Rongjin Li, Wenping Hu
Summary: Research on organic single crystals grown on a liquid substrate and used to construct single-crystalline OSVs revealed high magnetoresistance responses and spin transport properties. A magnetoresistance value as high as 17% was measured with an intermediate layer thickness of 269 nm. Spin transport was observed in single crystals up to a thickness of 457 nm, much larger than that of polycrystalline thin films.
SCIENCE CHINA-MATERIALS
(2021)
Article
Physics, Multidisciplinary
E. Tisserond, J. N. Fuchs, M. O. Goerbig, P. Auban-Senzier, C. Meziere, P. Batail, Y. Kawasugi, M. Suda, H. M. Yamamoto, R. Kato, N. Tajima, M. Monteverde
Article
Physics, Applied
Hiroshi M. Yamamoto, Masayuki Suda, Yoshitaka Kawasugi
JAPANESE JOURNAL OF APPLIED PHYSICS
(2018)
Article
Multidisciplinary Sciences
Yoshitaka Kawasugi, Kazuhiro Seki, Satoshi Tajima, Jiang Pu, Taishi Takenobu, Seiji Yunoki, Hiroshi M. Yamamoto, Reizo Kato
Article
Materials Science, Multidisciplinary
Hiroshi Ito, Yusuke Edagawa, Jiang Pu, Hiroki Akutsu, Masayuki Suda, Hiroshi M. Yamamoto, Yoshitaka Kawasugi, Rie Haruki, Reiji Kumai, Taishi Takenobu
PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS
(2019)
Article
Physics, Multidisciplinary
Ryotaro Kobara, Shin Igarashi, Yoshitaka Kawasugi, Ryusei Doi, Toshio Naito, Masafumi Tamura, Reizo Kato, Yutaka Nishio, Koji Kajita, Naoya Tajima
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN
(2020)
Article
Physics, Multidisciplinary
Yoshinari Unozawa, Yoshitaka Kawasugi, Masayuki Suda, Hiroshi M. Yamamoto, Reizo Kato, Yutaka Nishio, Koji Kajita, Takao Morinari, Naoya Tajima
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN
(2020)
Article
Crystallography
Hengbo Cui, Hamish H. -M. Yeung, Yoshitaka Kawasugi, Takaaki Minamidate, Lucy K. Saunders, Reizo Kato
Summary: A single-component molecular crystal [Pd(dddt)(2)] has been found to exhibit unique resistivity behavior under high pressure, with high-pressure single-crystal structure analysis revealing pressure-induced structural disorder. Calculations show that the electronic state at high pressure is more complex than previously thought. Magnetoresistance measurements under high pressure suggest unusual behavior originating from the Dirac electron state.
Article
Crystallography
Yoshitaka Kawasugi, Hiroshi M. Yamamoto
Summary: The physics of quantum many-body systems have been explored using bulk correlated materials and moire superlattices. In this review, a band-filling- and bandwidth-tunable electric double-layer transistor is introduced as an intermediate platform for studying these systems. Experimental results on a real organic Mott insulator reveal both electron and hole doping induced superconductivity and non-Fermi liquid behaviors in the same sample. Model calculations based on an anisotropic triangular lattice explain many of these phenomena and the doping asymmetry, highlighting the importance of the noninteracting band structure.
Article
Physics, Multidisciplinary
Ayano Mori, Yoshitaka Kawasugi, Ryusei Doi, Toshio Naito, Reizo Kato, Yutaka Nishio, Naoya Tajima
Summary: We investigated the interlayer magnetoresistance in an organic massless Dirac electron system alpha-(BEDT-TTF)(2)I-3 at different pressures. The experimental results demonstrate that the width of the zero mode is much narrower than that of the other Landau levels due to carrier scattering.
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN
(2022)
Article
Physics, Multidisciplinary
Naoya Tajima, Yoshitaka Kawasugi, Takao Morinari, Ryuhei Oka, Toshio Naito, Reizo Kato
Summary: Theoretical and experimental studies have shown that the electronic structure of alpha-(BEDT-TTF)2I3 can be described as two-dimensional Dirac fermions under pressure. When the interlayer tunneling is coherent, the system's electronic structure becomes three-dimensional, and a peak structure is expected to appear in the interlayer resistivity under magnetic fields. We have theoretically and experimentally observed this peak in the interlayer resistivity at low temperatures and high magnetic fields. From the experiment, we estimated the magnitude of the interlayer tunneling to be around 1 meV. Our results provide an opportunity for investigating the three-dimensional electronic structure of alpha-(BEDT-TTF)2I3.
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN
(2023)
Article
Physics, Applied
Yoshitaka Kawasugi, Haruto Suzuki, Hiroshi M. Yamamoto, Reizo Kato, Naoya Tajima
Summary: Uniaxial pressure can alter the properties of low-dimensional systems and induce electronic phase transitions. The unique features of the molecular massless Dirac electron system a-(BEDT-TTF)(2)I-3, such as its proximity to the Dirac point, strong electron correlation, and charge-ordered insulating state, have led to intensive studies. However, the Dirac state was previously only achieved under high pressure, which limits the measurement of physical properties. This study demonstrates that the Dirac state of a-(BEDT-TTF)(2)I-3 can be realized by applying uniaxial bending strain without the need for a pressure cell.
APPLIED PHYSICS LETTERS
(2023)
Article
Physics, Multidisciplinary
Yoshitaka Kawasugi, Shutaro Yamazaki, Andrej Pustogow, Naoya Tajima
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN
(2023)
Article
Multidisciplinary Sciences
A. Pustogow, Y. Kawasugi, H. Sakurakoji, N. Tajima
Summary: Researchers achieve a precise mapping of the spin-gapped phase in the triangular-lattice Mott insulator kappa-(BEDT-TTF)2Cu2(CN)3 by ultrahigh-resolution strain tuning, revealing a state with charge localization and a gap size of 30-50 K. The spin-gapped insulating state persists until unconventional superconductivity and metallic transport emerge at T -> 0, suggesting a low-entropy nature of the spin-singlet ground state.
NATURE COMMUNICATIONS
(2023)
Article
Materials Science, Multidisciplinary
Yoshitaka Kawasugi, Hikaru Masuda, Masashi Uebe, Hiroshi M. Yamamoto, Reizo Kato, Yutaka Nishio, Naoya Tajima
Summary: The study investigates the SdH oscillations in alpha-(BETS)2I-3 molecular conductor at 1.7K, showing that it is in the Dirac fermion phase under pressure. While the material is near the phase transition between strongly correlated insulating and Dirac fermion phases, it is a possible candidate for an ambient-pressure molecular Dirac fermion system. The Berry phase is zero at ambient pressure, but a π Berry phase emerges under pressure, indicating a suppressed metal-insulator crossover at around 0.5 GPa. This contrasts with the behavior of the pioneering molecular Dirac fermion system alpha-(BEDT-TTF)2I-3.
Article
Materials Science, Multidisciplinary
Yoshitaka Kawasugi, Kazuhiro Seki, Jiang Pu, Taishi Takenobu, Seiji Yunoki, Hiroshi M. Yamamoto, Reizo Kato
Article
Materials Science, Multidisciplinary
Jinfei Dai, Chenjing Zhao, Jie Xu, Hossein Roshan, Hua Dong, Francesco Di Stasio, Fang Yuan, Bo Jiao, Zhaoxin Wu
Summary: In this study, the performance of perovskite nanocrystal light emitting diodes (PNC-LEDs) was enhanced through rational device structure design and the application of high-performance perovskite nanocrystal emitting layers.
ORGANIC ELECTRONICS
(2024)
Article
Materials Science, Multidisciplinary
Jia-Hua Yeh, Suhendro Purbo Prakoso, Leon Lukhas Santoso, Shi-Ju Chen, Bryan Chiang, Ju-Chieh Cheng, Ru-Ning Zhang, Yu-Cheng Chiu
Summary: This study demonstrates the application of a renewable material called dextrin-SMS in the production of electret filters and transistor memory. Dextrin-SMS material can maintain prolonged electrostatic charges and has a relatively wide memory window, making it suitable for the production of biodegradable face masks and green electronics.
ORGANIC ELECTRONICS
(2024)
Article
Materials Science, Multidisciplinary
Ahmad Telfah, Qais M. Al-Bataineh, Ahmad A. Ahmad, Rund Abu-Zurayk, Carlos J. Tavares, Johannes Etzkorn, Farzad Foadian
Summary: Polyacrylic acid complexed with polyaniline (PAA/PANI) composite materials have the potential to form organic mixed ion-electron conductive (OMIEC) films, which can be used in optoelectronic and energy storage applications. The composite films are formed through an acid-base reaction, resulting in strong electrostatic interactions and intermolecular hydrogen bonds between PANI and PAA. The separation of PANI-rich domains from PAA-rich matrix in the composite films is observed. The electrical conductivity of the composite films is higher when the content of PANI is 33 wt%, due to the high ionic-electronic coupling at the interface between phase-separated regions.
ORGANIC ELECTRONICS
(2024)
Article
Materials Science, Multidisciplinary
Min-Chih Hou, Dian Luo, Yu-Ting Huang, Shun-Wei Liu, Chin-Wei Lu, Chih-Hao Chang, Hai-Ching Su
Summary: Light-emitting electrochemical cells (LECs) have great potential for novel emission applications, but their relatively low device efficiency hinders their competitiveness with other emission technologies. A study finds that increasing the concentration of small TiO2 nano-particles in the diffuser film can enhance light extraction and improve the device efficiency of LECs.
ORGANIC ELECTRONICS
(2024)
Article
Materials Science, Multidisciplinary
Qiaoli Niu, Yao Xu, Jun Yang, Wei Hua, Baoxiang Chai, Zequan Zhang, Yuhui Ma, Wenjin Zeng, Ana Flavia Nogueira, Ruidong Xia
Summary: By introducing CPB as a defect passivation agent in the perovskite precursor solution, the optoelectronic properties of perovskite films can be significantly improved and non-radiative carrier recombination can be effectively suppressed. CPB-modified perovskite solar cells exhibit lower trap-state density and stronger carrier migration capability, leading to enhanced power conversion efficiency and stability.
ORGANIC ELECTRONICS
(2024)
Article
Materials Science, Multidisciplinary
Hulya Ozturk Dogan, Fatma Yildirim, Zeynep Orhan, Ali Ben Ahmed, Mostefa Benhaliliba, Sakir Aydogan
Summary: In this study, efficient self-powered visible and UV photodetectors based on hybrid organic-inorganic materials were demonstrated. The photodetectors showed excellent UV detecting capability and good photoresponsivity.
ORGANIC ELECTRONICS
(2024)
