Article
Materials Science, Multidisciplinary
Xiucheng Wei, Pinku Roy, Zihao Yang, Di Zhang, Zihao He, Ping Lu, Olivia Licata, Haiyan Wang, Baishakhi Mazumder, Nag Patibandla, Yong Cao, Hao Zeng, Mingwei Zhu, Quanxi Jia
Summary: This study achieved high-quality ultrathin epitaxial NbN films using PVD technology at low temperatures, opening up new possibilities for quantum devices. The research revealed a close correlation between film thickness and superconducting properties, with lattice strain observed in films below 20 nm.
MATERIALS RESEARCH LETTERS
(2021)
Article
Materials Science, Multidisciplinary
Olivia G. Licata, Jith Sarker, Mukesh Bachhav, Pinku Roy, Xiucheng Wei, Zihao Yang, Nag Patibandla, Hao Zeng, Mingwei Zhu, Quanxi Jia, Baishakhi Mazumder
Summary: This study investigates the effect of nanoscale chemistry and interfacial abruptness on the superconducting properties of NbN films. The results provide insights for optimizing material design and growth of superconducting NbN films.
MATERIALS CHEMISTRY AND PHYSICS
(2022)
Article
Physics, Multidisciplinary
Alexander Weitzel, Lea Pfaffinger, Ilaria Maccari, Klaus Kronfeldner, Thomas Huber, Lorenz Fuchs, James Mallord, Sven Linzen, Evgeni Il'Ichev, Nicola Paradiso, Christoph Strunk
Summary: We conducted a comprehensive investigation of the Berezinskii-Kosterlitz-Thouless transition in ultrathin strongly disordered NbN films. Our measurements of resistance, current-voltage characteristics, and kinetic inductance on the same device provide consistent evidence for a sharp unbinding transition of vortex-antivortex pairs, which can be explained by standard renormalization group theory without extra assumptions of inhomogeneity. Our experiments demonstrate that the previously observed broadening of the transition is not intrinsic to strongly disordered superconductors, and provide a clean starting point for studying dynamical effects at the Berezinskii-Kosterlitz-Thouless transition.
PHYSICAL REVIEW LETTERS
(2023)
Article
Physics, Condensed Matter
Yuan Fang, Ding Wang, Peng Li, Hang Su, Tian Le, Yi Wu, Guo-Wei Yang, Hua-Li Zhang, Zhi-Guang Xiao, Yan-Qiu Sun, Si-Yuan Hong, Yan-Wu Xie, Huan-Hua Wang, Chao Cao, Xin Lu, Hui-Qiu Yuan, Yang Liu
Summary: This study reports on the growth, electronic structure, and superconductivity of ultrathin epitaxial CoSi2 films on Si (111). The research shows the influence of quantum well states and multi-layer structure on superconductivity.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2021)
Article
Chemistry, Physical
Shailesh Kalal, Mukul Gupta, Rajeev Rawat
Summary: The study focused on the effects of nitrogen concentration on the structural and superconducting properties of niobium mononitride (NbN) thin films deposited using reactive magnetron sputtering of Nb at different partial pressures of N2. It was found that at low nitrogen concentrations, N atoms occupy interstitial sites within Nb leading to lattice distortion, while at intermediate nitrogen concentrations, nearly stoichiometric NbN phase emerges, and further nitridation results in expansion and distortion of NbN. High magnetic field resistivity measurements showed that optimal nitrogen concentration at R-N2 = 16% resulted in maximized superconducting transition temperature (Tc) and upper critical field (HC2(0)). Additionally, applying a radio frequency (rf) bias during the growth of NbN thin films enhanced adatom mobility leading to improved crystalline ordering and higher Tc of 13.2 K.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Multidisciplinary Sciences
Xiaoqian Zhang, Qiangsheng Lu, Wenqing Liu, Wei Niu, Jiabao Sun, Jacob Cook, Mitchel Vaninger, Paul F. Miceli, David J. Singh, Shang-Wei Lian, Tay-Rong Chang, Xiaoqing He, Jun Du, Liang He, Rong Zhang, Guang Bian, Yongbing Xu
Summary: Growth and properties of single- and few-layer CrTe2 on bilayer graphene by molecular beam epitaxy (MBE) have shown intrinsic ferromagnetism with a Curie temperature up to 300 K and perpendicular magnetic anisotropy, providing a new avenue for developing large-scale 2D magnet-based spintronics devices.
NATURE COMMUNICATIONS
(2021)
Article
Nanoscience & Nanotechnology
I. Hong Ho, Ching-Wen Chang, Yen-Lin Chen, Wan-Yu Chang, Ting-Jui Kuo, Yu-Jung Lu, Shangjr Gwo, Hyeyoung Ahn
Summary: This study successfully grows ultrathin TiN films with excellent surface morphology and high optical transparency using nitrogen plasma-assisted molecular-beam epitaxy (MBE) method. The films exhibit good dielectric properties and electrical conductivity, making them suitable for robust, low cost, and large-area transparent conductive electrodes.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Chemistry, Physical
Seo Young Jang, Hye Min Lee, Ju Young Sung, Se Eun Kim, Jae Deock Jeon, Yewon Yun, Sang Mo Moon, Joung Eun Yoo, Ji Hyeon Choi, Tae Joo Park, Sang Woon Lee
Summary: The epitaxial growth of NbN thin film was achieved for the first time using ALD with NbCl5 and NH3 as precursors. The matching lattice structure between NbN and MgO allowed for epitaxial growth with a small lattice mismatch. The Cl impurity concentration in epitaxial NbN thin films was significantly lower compared to those grown on a SiO2 substrate, potentially due to a bond length change induced by a residual strain at the NbN/MgO interface. The epitaxial growth of NbN thin films led to improved crystallinity and a 50% reduction in resistivity.
APPLIED SURFACE SCIENCE
(2023)
Article
Materials Science, Multidisciplinary
A. I. Lomakin, E. M. Baeva, A. D. Triznova, N. A. Titova, P. I. Zolotov, A. Semenov, D. E. Sunegin, A. Lubenchenko, A. I. Kolbatova, G. N. Goltsman
Summary: This experimental study investigates the impact of disorder on electronic parameters and inelastic scattering mechanisms in ultrathin superconducting NbN films. The increase in disorder leads to a decrease in critical temperature Tc, from 11.5K to 3.4K. The measurement of magnetoconductance reveals that the electron-phonon scattering rate r-1e-ph and its temperature dependence are insensitive to disorder, suggesting the need for further research on the e-ph scattering in ultrathin disordered films.
Article
Materials Science, Multidisciplinary
N. Ortiz Hernandez, Z. Salman, T. Prokscha, A. Suter, J. R. L. Mardegan, S. Moser, A. Zakharova, C. Piamonteze, U. Staub
Summary: The study on ultrathin T-CuO films using low-energy muon spin rotation and x-ray magnetic circular dichroism (XMCD) techniques revealed the presence of antiferromagnetic order with a transition temperature higher than 200 K. The magnetic structure includes pinned Cu2+ moments parallel to the sample surface and isotropic paramagnetic moments, with some Cu moments pinned by an AFM ordering primarily in the plane of the film. The experimental findings indicate deviations from theoretical predictions in the magnetic order of T-CuO ultrathin films.
Article
Materials Science, Multidisciplinary
Yuichi Fujita, Taisuke Sasaki, Yuya Sakuraba
Summary: This article demonstrates the process of improving the surface morphology of an epitaxial NbN layer and the epitaxial growth of a Co-based Heusler alloy, Co2FeSi, film on the surface-flattened NbN epilayer. By using Cr buffer layers and post-deposition annealing, the surface roughness of the NbN layers is successfully suppressed, resulting in atomically flat interfaces with the CFS layers. However, minor diffusion of N atoms from the NbN layer into the Cr buffer layer is observed, which may affect the crystallinity of the NbN layer.
Article
Chemistry, Physical
Rocio M. Gutierrez-Perez, Diego I. Zubiate-Perez, Ricardo Lopez Anton, Maria E. Fuentes-Montero, Jose T. Holguin-Momaca, Oscar O. Solis-Canto, Adriana Alvidrez-Lechuga, Juan Antonio Gonzalez, Sion F. Olive-Mendez
Summary: This study provides a comprehensive analysis of the magnetization and effective perpendicular magnetic anisotropy (PMA) of epitaxial D0(22)-Mn3+xGa ultrathin films. The growth method significantly affects the uniaxial PMA and thickness of non-magnetic layers, while the saturation magnetization remains unchanged. These results can be explained by interface structural defects caused by lattice mismatch and growth method.
SURFACES AND INTERFACES
(2022)
Article
Engineering, Electrical & Electronic
Tomohiro Ichinose, Daisuke Miura, Hiroshi Naganuma
Summary: BiFeO3 films were grown using RF magnetron sputtering under various conditions to optimize the Bi content and achieve high-quality parameters. Advanced analyses were conducted to examine the crystal structure and ferroelectric properties of the films, yielding important insights for the study of multiferroic materials. This research provides a method for investigating crystal symmetry in ultrathin films, which could have implications for the development of high-performance sensors incorporating multiferroic tunnel junctions.
ACS APPLIED ELECTRONIC MATERIALS
(2021)
Article
Physics, Applied
Yong Zhong, Ziyuan Dou, Rui-Feng Wang, Yan-Feng Lv, Sha Han, Hang Yan, Can-Li Song, Xu-Cun Ma, Qi-Kun Xue
Summary: This study presents the epitaxial growth and surface characterization of tetragonal CuO thin film, revealing electronic structure features and contributing to a deeper understanding of high-T-C superconductivity in cuprates.
APPLIED PHYSICS LETTERS
(2021)
Article
Materials Science, Multidisciplinary
Kyoungjun Lee, Jinho Byun, Kunwoo Park, Sungsu Kang, Myeong Seop Song, Jungwon Park, Jaekwang Lee, Seung Chul Chae
Summary: This study demonstrates a method to retain information with the least loss of energy in ubiquitous mobile devices. By integrating a ferroelectric HfO2 thin film directly on a silicon wafer, a colossal resistance change in the ferroelectric tunnel junction is achieved. The On/Off ratio is improved by altering the polarization direction in the metal-ferroelectric-semiconductor junction. The high CMOS compatibility of HfO2 is of great significance for the widespread application of ferroelectric tunnel barriers.
APPLIED MATERIALS TODAY
(2022)
Article
Crystallography
Alexey Shuvaev, Lei Pan, Peng Zhang, Kang L. Wang, Andrei Pimenov
Summary: The article discusses research on the Quantum Anomalous Hall Effect (QAHE), exploring the possibility of achieving QAHE in magnetic topological insulators under specific conditions, and observing polarization rotation steps approaching the fine structure constant in experiments.
Article
Physics, Multidisciplinary
A. Shuvaev, V. M. Muravev, P. A. Gusikhin, J. Gospodaric, A. Pimenov, I. Kukushkin
Summary: The experimental discovery of superluminal electromagnetic 2D plasma waves in a high-quality GaAs/AlGaAs two-dimensional electron system on a dielectric substrate is reported. The study shows a strong hybridization between plasma and Fabry-Perot light modes at large two-dimensional densities, and the plasma resonance split into two modes in the presence of a perpendicular magnetic field, each corresponding to a specific sense of circular polarization. The experimental results are in good agreement with the theory.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Applied
A. S. Astrakhantseva, A. Shuvaev, P. A. Gusikhin, A. Pimenov, I. Kukushkin, V. M. Muravev
Summary: We studied the terahertz response of a dielectric membrane with a high-mobility two-dimensional electron system (2DES). The developed device exhibits electromagnetic transparency above the plasma frequency determined by the 2DES density and membrane thickness. Our results demonstrate highly tunable opacity in the low-frequency region, with potential applications in active terahertz devices.
APPLIED PHYSICS LETTERS
(2022)
Article
Physics, Applied
V. M. Muravev, A. Shuvaev, A. S. Astrakhantseva, P. A. Gusikhin, I. V. Kukushkin, A. Pimenov
Summary: We have devised an electronically controllable plasmonic modulator based on GaAs semiconductor technology, capable of changing the phase of the transmitted electromagnetic wave. We demonstrated its phase tunability up to 41 degrees at an insertion loss of -2.2 dB. The phase shifter operates at frequencies up to 0.27 THz and temperatures up to 80 K, with the potential for scalability to a planar phased array.
APPLIED PHYSICS LETTERS
(2022)
Article
Chemistry, Multidisciplinary
Alexey Shuvaev, Vlad Dziom, Jan Gospodaric, Elena G. Novik, Alena A. Dobretsova, Nikolay N. Mikhailov, Ze Don Kvon, Andrei Pimenov
Summary: This study investigates the properties of mercury telluride thin films with a critical thickness through magnetooptical spectroscopy. The results show that the material has a gapless Dirac band structure, and the properties of charge carriers can be modulated by doping and optical gating.
Article
Physics, Applied
Alexey Shuvaev, Lei Pan, Lixuan Tai, Peng Zhang, Kang L. L. Wang, Andrei Pimenov
Summary: The integer quantum Hall effect combined with the speed of light provides a dimensionless reference number, the fine-structure constant alpha & AP; 1/137, which can be extracted from a physical experiment. Measuring this constant and its possible variation on cosmological time scales is of great importance for fundamental science. A direct optical experiment can determine the fine-structure constant by measuring the quantized rotation of light polarization, and the quantum anomalous Hall effect allows obtaining a universal quantized value in zero magnetic field.
APPLIED PHYSICS LETTERS
(2022)
Article
Physics, Multidisciplinary
E. Constable, L. Bergen, A. Shuvaev, J. Wettstein, L. Weymann, E. Malysheva, A. Pimenov, M. Guennou
Summary: Spectroscopic measurements were conducted to study the far-infrared phonon dynamics of a model antiferroelectric crystal at low temperature. The observed polar soft mode confirms the expected behavior of a displacive antiferroelectric transition, which involves a close-lying polar phase in an otherwise centrosymmetric structure. The incomplete softening of the polar soft mode provides insight into the energy barrier between neighboring states during the antiferroelectric transition. A biquadratic Landau potential incorporating symmetry constraining effective interactions between displaced ions was used to model the dynamics. Additionally, a scaling of the effective antipolar interaction was observed, indicating sublattice polarization in the antiferroelectric phase.
PHYSICAL REVIEW RESEARCH
(2023)
Article
Materials Science, Multidisciplinary
M. L. Savchenko, A. Shuvaev, I. A. Dmitriev, S. D. Ganichev, Z. D. Kvon, A. Pimenov
Summary: This study demonstrates that the inherent property of microwave-induced resistance oscillations (MIRO) in solid-state two-dimensional electron systems (2DES) is not immune to the sense of circular polarization. The researchers found that the MIRO signal can be increased up to 30 times for the cyclotron resonance active helicity, which is consistent with the transmission and absorption shape of Drude. Additionally, the study investigates the extrinsic near-field effects that can produce an apparent immunity of the photoresponse using 2DES as a sensitive sensor of the polarization state.
Article
Materials Science, Multidisciplinary
V. Dziom, A. Shuvaev, J. Gospodaric, E. G. Novik, A. A. Dobretsova, N. N. Mikhailov, Z. D. Kvon, Z. Alpichshev, A. Pimenov
Summary: Spin-orbit coupling in thin HgTe quantum wells provides a solid state platform to observe and control nontrivial electrodynamic phenomena. The terahertz (THz) transparency in a 6.5-nm-thick HgTe layer is determined by the fine-structure constant and is close to the critical thickness separating phases with different electronic band structure. THz spectroscopy in a magnetic field provides direct evidence of asymmetric spin splitting of the Dirac cone, enabling optical control of edge spin currents in the quantum wells.
Article
Materials Science, Multidisciplinary
Jan Gospodaric, Alexey Shuvaev, Nikolai N. Mikhailov, Ze D. Kvon, Elena G. Novik, Andrei Pimenov
Summary: Quantum wells based on mercury telluride thin films exhibit a range of unusual physical properties, such as insulator, two-dimensional Dirac semimetal, and three-dimensional topological insulator. Experimental and theoretical studies on two HgTe QWs with an inverted energy spectrum have successfully realized two-dimensional semimetallic states, with band structures obtained through magneto-optical spectroscopy and capacitance measurements. The results show good agreement with theoretical calculations, demonstrating the efficiency of using cyclotron resonance experiments to directly obtain band structures of semimetallic two-dimensional materials.
Article
Materials Science, Multidisciplinary
J. Gospodaric, V Dziom, A. Shuvaev, A. A. Dobretsova, N. N. Mikhailov, Z. D. Kvon, E. G. Novik, A. Pimenov
Article
Materials Science, Multidisciplinary
S. K. Gotovko, L. E. Svistov, A. M. Kuzmenko, A. Pimenov, M. E. Zhitomirsky
Article
Materials Science, Multidisciplinary
A. M. Kuzmenko, V Dziom, A. Shuvaev, Anna Pimenov, D. Szaller, A. A. Mukhin, V. Yu Ivanov, A. Pimenov
Article
Materials Science, Multidisciplinary
J. Gospodaric, V Dziom, A. Shuvaev, A. A. Dobretsova, N. N. Mikhailov, Z. D. Kvon, A. Pimenov
Article
Multidisciplinary Sciences
D. Szaller, A. Shuvaev, A. A. Mukhin, A. M. Kuzmenko, A. Pimenov
PHYSICAL SCIENCES REVIEWS
(2020)
