Article
Physics, Condensed Matter
Y. H. Zan, S. L. Ban
Summary: In symmetric MgxZn1-xO/ZnO quantum wells, the electron states and optical phonon modes are clarified using the dielectric continuum model, uniaxial model, and force balance equation. The electronic mobility affected by optical phonons is obtained through a weight model considering mixed phases in MgxZn1-xO. Results show fluctuations in QW's barriers in mixed phases region and different influences of WZ and RS phases on electronic mobility in HEMTs design.
SUPERLATTICES AND MICROSTRUCTURES
(2021)
Article
Chemistry, Physical
Yannic U. Staechelin, Michael Deffner, Sonja Krohn, Christian Castillo Delgadillo, Jan Steffen Niehaus, Holger Lange
Summary: By optical and THz pump-probe spectroscopy, we find that only shell-located electrons in quantum rods contribute to photoconductivity, while core-located carriers form immobile excitons that respond to external electrical fields.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Materials Science, Multidisciplinary
Qiuliang Zhong, Cheng Wu, Xiaoming Yu, Xuan Yu, Zhenhua Li, Qian Qiao, Yingtang Zhou, Yu Cao
Summary: In recent years, self-powered Schottky ultraviolet photodetectors have gained attention due to their low cost and zero-bias response. However, weak light response has limited the development of high-performance self-powered Schottky devices. In this study, the introduction of a MgxZn1-xO capping layer improved the device performance, resulting in increased photocurrent, responsivity, and linear dynamic range.
Article
Engineering, Electrical & Electronic
DongFeng Liu
Summary: Electron transport in MgxZn1-xO/ZnO heterostructures at room temperature is simulated using the ensemble Monte Carlo method. Various electron scattering mechanisms are considered, and it is found that electron escape scattering is a main limiting factor for drift velocity, while the competition between interface roughness and intersubband polar optical phonon scattering plays an important role in electron drift velocity change with increasing Mg mole fractions.
JOURNAL OF COMPUTATIONAL ELECTRONICS
(2023)
Article
Chemistry, Physical
Yaju Zhang, Huanxin Su, Hui Li, Zhongshuai Xie, Yuanzheng Zhang, Yan Zhou, Liya Yang, Haowei Lu, Guoliang Yuan, Haiwu Zheng
Summary: This study investigates the integration of pyroelectric and photovoltaic effects in BFO/Au/ZnO heterostructures, demonstrating superior photoelectric performance.
Article
Nanoscience & Nanotechnology
Jaeyoung Jeon, Kitae Eom, Yunhwa Hong, Chang-Beom Eom, Kwang Heo, Hyungwoo Lee
Summary: This study achieved a strong photoresponse of the 2DEG in a Pt/LAO/STO heterostructure with a maximum photoresponsivity of about 1.11 x 10(7)% by adopting a vertical tunneling configuration. Oxygen vacancy defects played a critical role in enhancing the tunneling photocurrent, and research consistently supported the contribution of photoexcited hot electrons from the oxygen vacancies to tunneling conduction under UV light.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Engineering, Electrical & Electronic
DongFeng Liu, GuoWei Chen
Summary: The energy level structures of MgxZn1-xO/ZnO/MgxZn1-xO quantum wells with different geometrical structures and material compositions have been obtained. Tunable terahertz intersubband absorption can be achieved by adjusting the Mg composition and well width. The linewidth broadening is analyzed by including electron scattering mechanisms such as piezoelectric acoustic phonon, polar optical phonon, interface roughness, and random alloy scattering. The findings show that increasing the Mg composition or decreasing the well width can result in high-frequency terahertz intersubband absorption, with interface roughness playing a significant role in linewidth broadening.
JOURNAL OF NANOELECTRONICS AND OPTOELECTRONICS
(2022)
Article
Physics, Multidisciplinary
A. R. Khisameeva, A. V. Shchepetilnikov, Yu. A. Nefyodov, I. V. Kukushkin
Summary: In this study, microwave-induced magnetoresistance oscillations were investigated in high-quality ZnO/MgxZn1-xO heterojunctions using a contactless technique. At least three oscillations were well resolved in the high-frequency conductivity when the sample was exposed to exciting microwave radiation in low magnetic fields. The absence of Ohmic contacts or metallization on the sample surface provided additional information for understanding the origin of this phenomenon.
Article
Chemistry, Multidisciplinary
Chadrasekhar Loka, Kee-Sun Lee
Summary: Ag-Ag2O-ZnO nanocomposite with localized surface plasmon resonance (LSPR) and p-n heterojunction structure was synthesized by hydrothermal process, which effectively improved the photocatalytic efficiency and suppressed the recombination of photogenerated electron-hole pairs. The nanocomposite exhibited excellent photocatalytic activity and achieved high degradation efficiency for different dyes under visible-light irradiation.
Article
Chemistry, Multidisciplinary
Jia Liu, Fengjing Liu, Haining Liu, Junyi Yue, Jiyou Jin, Julienne Impundu, Hui Liu, Zhu Yang, Zhisheng Peng, Haonan Wei, Chao Jiang, Yong Jun Li, Liming Xie, Lianfeng Sun
Summary: The study presented the construction of a 1D-3D ZnO/CsPbBr3 p-n junction with superior rectification and photodetection performance. As a rectifier, it exhibited high rectification ratio and ambipolar transfer characteristics; as a photodetector, it covered light from ultraviolet to visible light with high photoelectric switching ratio and responsivity.
Article
Chemistry, Multidisciplinary
Youngdong Yoo, Minjung Kim, Bongsoo Kim
Summary: In this study, 3D hierarchical plasmo-photonic nanoarchitectures were successfully fabricated by epitaxially integrating semiconducting zinc oxide (ZnO) nanowires with vertically oriented plasmonic gold (Au) and silver (Ag) nanoplatforms, and their growth mechanisms were investigated. The developed growth mechanism can be generally employed to fabricate 3D hierarchical plasmo-photonic nanoarchitectures.
Article
Materials Science, Multidisciplinary
Xiang-Hong Chen, Dong-Yu Hou, Zhi-Xin Hu, Kuang-Hong Gao, Zhi-Qing Li
Summary: In this paper, the formation mechanisms of two-dimensional electron gas (2DEG) near the interfaces of (001) Zn1-xMgxO/ZnO heterostructures were investigated using first-principles calculations. The results showed that neither polarity discontinuity nor thick Zn1-xMgxO layers can lead to the formation of 2DEG. The presence of oxygen vacancies near the interface or the absorption of hydrogen atoms, oxygen atoms, or OH groups on the Zn1-xMgxO film surface plays a key role in the formation of 2DEG in thin Zn1-xMgxO layers. These findings provide insights into the sources of 2DEGs in Zn1-xMgxO/ZnO heterostructures at the electronic structure level.
Review
Chemistry, Multidisciplinary
Serguei P. Murzin
Summary: Nanostructured metal oxides are attracting significant interest in advanced research and high-tech industries due to their wide range of applications. Studies focused on controlling the morphology of materials containing copper and zinc oxide nanowires are limited, but relevant considering their sensitivity and difficulty in synthesis. The use of nanoheterojunctions and innovative techniques like laser-induced vibrations show promise for improving the physical properties of oxide heterostructures.
APPLIED SCIENCES-BASEL
(2023)
Article
Chemistry, Physical
Shuxian Sun, Jiahe Zang, Jiafeng Ruan, Fang Fang, Dalin Sun, Yun Song, Fei Wang
Summary: A two-dimensional sheet morphology MOF-coated CuGaSe2@ZnSe-NC heterostructure has been synthesized and utilized as an anode material for sodium ion batteries, showing stable capacity of 276 mAh g(-1) over 2000 cycles at a high current density of 2.0 A g(-1).
ACS APPLIED ENERGY MATERIALS
(2021)
Article
Chemistry, Multidisciplinary
Amina Zafar, Muhammad Younas, Syeda Arooj Fatima, Lizhi Qian, Yanguo Liu, Hongyu Sun, Rubina Shaheen, Amjad Nisar, Shafqat Karim, Muhammad Nadeem, Mashkoor Ahmad
Summary: The successful synthesis of large-scale ZnO-ZnS heterostructures and the mechanism of sulfur atoms filling oxygen vacancies to induce charge transfer from ZnO to ZnS were discovered, forming a capacitor-like structure at the interface. By fitting an equivalent circuit model, the electrical behaviors of different phases were well explained, leading to the identification of a systematic approach to enhance the dielectric energy-storage performance.
Article
Physics, Multidisciplinary
Yuma Okazaki, Takehiko Oe, Minoru Kawamura, Ryutaro Yoshimi, Shuji Nakamura, Shintaro Takada, Masataka Mogi, Kei S. Takahashi, Atsushi Tsukazaki, Masashi Kawasaki, Yoshinori Tokura, Nobu-Hisa Kaneko
Summary: The quantum anomalous Hall effect (QAHE) is a transport phenomenon where the Hall resistance is quantized to the von Klitzing constant, with a precision of 10 parts per billion demonstrated in this study. By directly comparing QAHE with the quantum Hall effect (QHE), it has been confirmed that QAHE meets the required level of quantization accuracy as a primary standard of electric resistance. This high accuracy of quantization is achieved by using a weak magnetic field supplied by a permanent disc magnet to align the magnetization domains, paving the way for developing a quantum resistance standard without strong magnetic fields.
Article
Physics, Applied
Junichi Shiogai, Kohei Fujiwara, Tsutomu Nojima, Atsushi Tsukazaki
Summary: This study investigates the structural dependence of UMR in Fe-Sn heterostructure devices, revealing a weak dependence of UMR on interface configuration but an enhancement in UMR amplitude with increasing Fe-Sn layer thickness.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2022)
Article
Nanoscience & Nanotechnology
Kohei Fujiwara, Koya Shibata, Shunsuke Nishimura, Junichi Shiogai, Atsushi Tsukazaki
Summary: The effect of annealing on the crystalline ordering and physical properties in thin films of Co2FeSn is reported. The annealing process induced structural changes and significantly influenced the electrical and thermoelectric transport properties. These findings highlight the importance of annealing in studying the topological band features in Co2FeSn thin films.
Article
Materials Science, Multidisciplinary
Yoshihiro D. Kato, Yoshihiro Okamura, Susumu Minami, Reika Fujimura, Masataka Mogi, Ryutaro Yoshimi, Atsushi Tsukazaki, Kei S. Takahashi, Masashi Kawasaki, Ryotaro Arita, Yoshinori Tokura, Youtarou Takahashi
Summary: This research reveals that the large intrinsic anomalous Hall effect in the ferromagnetic nodal line semimetal Fe3GeTe2 is generated by the cooperation of flat bands and band crossings near the Fermi level. The study finds that two resonance structures in the terahertz and infrared magneto-optical spectroscopy are closely related to the anomalous Hall effect.
NPJ QUANTUM MATERIALS
(2022)
Article
Physics, Applied
Junichi Shiogai, Atsushi Tsukazaki
Summary: In this study, a freestanding single-crystalline FeSe membrane was prepared using a water-soluble Sr3Al2O6 sacrificial layer as a growth template. The FeSe membrane was fully relaxed with minimal degradation of its structural properties during the lift-off process. The freestanding FeSe membrane exhibited superconductivity below 4.2 K, while it was not observed in a compressed thin-film form.
APPLIED PHYSICS LETTERS
(2023)
Letter
Physics, Multidisciplinary
Minoru Kawamura, Masataka Mogi, Ryutaro Yoshimi, Takahiro Morimoto, Kei S. Takahashi, Atsushi Tsukazaki, Naoto Nagaosa, Masashi Kawasaki, Yoshinori Tokura
Summary: Adiabatic charge pumping is observed in a thin-film magnetic heterostructure of topological insulators, confirming the theoretical prediction of topological magnetoelectric effect. The pumped charge is proportional to the surface Hall conductivity, providing clues for its direct observation.
Article
Physics, Applied
Kohei Fujiwara, Junya Ikeda, Shun Ito, Atsushi Tsukazaki
Summary: Solid-liquid interfaces composed of functional inorganic materials and liquid electrolytes exhibit interesting responses when an electric bias is applied. By using an electric-double-layer device on a thin-film channel of magnetic Weyl semimetal Co3Sn2S2 with an ionic liquid gate electrolyte, it is shown that the thickness of the conducting channel can be effectively reduced with a negative gate voltage. This finding allows for the examination of the thickness dependence of the anomalous transport properties of Co3Sn2S2 in a single sample.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Masamichi Negishi, Kohei Fujiwara, Atsushi Tsukazaki
Summary: Pulsed-laser deposition is a widely used method to fabricate complex oxide thin films, and film composition is regulated by various conditions. This study reports an experimental scheme to tune the composition ratio in Mg-Ir-O films fabricated by pulsed-laser deposition. By examining different parameters, a wide range of composition ratio was regulated in the films, and a spinel-related crystalline phase was discovered in the Mg-rich compositions.
Article
Multidisciplinary Sciences
Kohei Fujiwara, Yasuyuki Kato, Hitoshi Abe, Shun Noguchi, Junichi Shiogai, Yasuhiro Niwa, Hiroshi Kumigashira, Yukitoshi Motome, Atsushi Tsukazaki
Summary: Amorphous semiconductors are widely used in electronic and energy-conversion devices. This study reveals that the short-range crystalline order in amorphous Fe-Sn films contributes to anomalous electrical and magneto-thermoelectric properties. This finding sheds light on the topology of amorphous materials and may enable the realization of functional topological amorphous electronic devices.
NATURE COMMUNICATIONS
(2023)
Article
Nanoscience & Nanotechnology
Saikat Das, Satoshi Sugimoto, Varun Kumar Kushwaha, Yusuke Kozuka, Shinya Kasai
Summary: Magnetization switching can be achieved by utilizing spin-orbit torque, which shows potential for developing non-volatile memory technologies. In this study, we observed charge-to-spin current conversion at the interface between ferromagnetic Ni0.8Fe0.2 and ferroelectric Bi2WO6 thin films. The resulting spin-orbit torque consists of damping-like and field-like components, with an estimated efficiency comparable to contemporary spintronic materials. We propose that the Rashba Edelstein effect and the spin-orbit proximity effect contribute to the charge-to-spin current conversion and the giant efficiency, respectively.
Article
Materials Science, Multidisciplinary
Motoki Osada, Kohei Fujiwara, Tsutomu Nojima, Atsushi Tsukazaki
Summary: The nickelate superconductor with infinite NiO2 layer was synthesized by reducing the perovskite precursor phase through topochemical reduction. By increasing the reduction temperature, La1-xSrxNiO2 films transformed from the insulating state to the superconducting state, with a maximum onset superconducting transition temperature T onset c of about 14K at x = 0.20. The electrical conduction in NiO2 planes is found to be a sensitive parameter for optimizing the reduction state. The systematic optimization of reduction temperature resulted in an expanded superconducting dome in the phase diagram with higher T onset c and wider x range (0.12 x 0.28) compared to previous reports.
PHYSICAL REVIEW MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Yusuke Kozuka, Taisuke T. Sasaki, Terumasa Tadano, Jun Fujioka
Summary: In this study, the fabrication and transport properties of SrPd3O4 and CaPd3O4 thin films as candidates of oxide Dirac semimetals are investigated. The observed weak temperature dependence suggests narrow-gap properties, but unintentionally doped holes hinder the discovery of the Dirac band. The study establishes the basic thermodynamics of thin-film fabrication and paves the way for exploring interesting properties of topological band structures.
SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
G. Senthil Murugan, Chanhyeon Lee, R. Kalaivanan, I. Panneer Muthuselvam, Yugo Oshima, Kwang-Yong Choi, R. Sankar
Summary: We studied the magnetic properties of the kagome ferromagnet Li9Cr3(P2O7)3(PO4)2 using various techniques. The results show ferromagnetic ordering at TC = 2.7 K and persistence of two-dimensional magnetic correlations up to temperatures as high as ~18 TC. We observed a change in spin dynamics at about T * = 4.4 TC and an unexpected suppression of the 7Li spin-lattice relaxation rate 1/T1 below 50 K.
Article
Materials Science, Multidisciplinary
Vasileios Niaouris, Mikhail Durnev, Xiayu Linpeng, Maria L. K. Viitaniemi, Christian Zimmermann, Aswin Vishnuradhan, Yusuke Kozuka, Masashi Kawasaki, Kai-Mei C. Fu
Summary: In this article, we present an experimental and theoretical study on the longitudinal electron spin relaxation of shallow donors in ZnO. The study found an inverse-power dependence of the spin relaxation rate on magnetic field, with the dominant contribution coming from the spin-orbit mechanism. Temperature and excitation energy were also found to have an impact on the results.
Article
Materials Science, Multidisciplinary
Suheon Lee, Tianyu Zhu, Y. Oshima, T. Shiroka, C. Wang, H. Luetkens, Haoming Yang, Minfeng Lu, K. -Y. Choi
Summary: We report the static and dynamical properties of a newly discovered S = 2 kagome antiferromagnet CsMn3F6(SeO3)(2). Three distinct regimes were identified, and the variations in spin correlations at different temperature ranges were explained.
