Article
Multidisciplinary Sciences
Kandammathe Valiyaveedu Sreekanth, Jayakumar Perumal, U. S. Dinish, Patinharekandy Prabhathan, Yuanda Liu, Ranjan Singh, Malini Olivo, Jinghua Teng
Summary: The researchers present a scalable Tamm plasmon cavity using phase change material with large resonance tunability and demonstrated tunable SERS by matching the plasmonic resonance with the molecule absorption for sensitivity enhanced biosensing.
NATURE COMMUNICATIONS
(2023)
Article
Chemistry, Physical
Liqiu Yang, Subodh C. Tiwari, Shogo Fukushima, Fuyuki Shimojo, Rajiv K. Kalia, Aiichiro Nakano, Priya Vashishta, Paulo S. Branicio
Summary: Nonadiabatic quantum molecular dynamics is used to investigate the evolution of photoexcited states in GeTe. Results reveal a nonthermal path for the loss of long-range order induced by photoexcitation, which triggers local disorder and promotes the formation of wrong bonds. These findings provide an electronic-structure basis for understanding the ultrafast changes in the structure and properties of GeTe and other phase-change materials induced by photoexcitation.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Nanoscience & Nanotechnology
Aivar Abrashuly, Constantinos Valagiannopoulos
Summary: Photonic memory devices can provide different outputs based on the input's past values, exhibiting multistability; nonlinear cylindrical metasurfaces can develop multiple responses based on the history of excitation intensities, offering a promising route for designing versatile optical devices.
Article
Physics, Multidisciplinary
Benjamin Verlhac, Lorena Niggli, Anders Bergman, Umut Kamber, Andrey Bagrov, Diana Iusan, Lars Nordstrom, Mikhail Katsnelson, Daniel Wegner, Olle Eriksson, Alexander A. Khajetoorians
Summary: This study presents an unusual magnetic transition in neodymium, where long-range multi-Q magnetic order emerges from a self-induced spin glass with increasing temperature. The local order of the spin glass phase is characterized using temperature-dependent spin-polarized scanning tunnelling microscopy, and the emergence of long-range multi-Q order is quantified. Analysis tools are developed to determine the glass transition temperature from measurements of spatially dependent magnetization. Atomistic spin dynamics simulations reproduce the observed phase transition and trace the origin of the high-temperature order. These findings demonstrate an example of order from disorder and provide a platform for studying the magnetization dynamics of a self-induced spin glass.
Article
Chemistry, Multidisciplinary
Jia-Qi Pan, Yun-Rui Chen, Meng-Ze Jia, Xin-Rong Yao, Xiao-Li Miao, Jie Zhang
Summary: Charge transfer complexes (CTCs) are a promising class of photothermal conversion materials that can efficiently absorb near-infrared light. However, co-crystallizing suitable donor and acceptor pairs to form CTCs remains challenging. This study demonstrates the manipulation of photothermal behavior in two distinct CTCs through charge transfer and electron transfer processes, opening a new avenue for optimizing the photothermal effect of CTCs.
Article
Physics, Multidisciplinary
Sanjib Banik, Kalipada Das, Kalpataru Pradhan, Indranil Das
Summary: We designed reversible multi-level resistance states in a half-doped charge-ordered manganite, SCSMO, by exploiting electronic phase separation. During thermal cycling, the system can be stabilized into several metastable states where magnetization and resistivity remain unaltered. Monte Carlo calculations suggest that the system freezes into a phase-separated metastable state due to disorder, outlining a pathway to control multi-level switching between four reversible metastable states.
Article
Engineering, Electrical & Electronic
Neeru Bala, Anup Thakur
Summary: In this study, doped Ge2Sb2Te5 alloys and thin films were prepared and their properties were investigated. The doped films retained amorphous structure and exhibited uniform and smooth morphology. Transmission spectra showed high transparency of the doped films in the near-infrared region. The doped GST thin films had a lower optical band gap compared to pure GST thin films.
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
(2022)
Article
Multidisciplinary Sciences
June Sang Lee, Nikolaos Farmakidis, C. David Wright, Harish Bhaskaran
Summary: This study introduces hybridized-active-dielectric nanowires for polarization-selective tunability and demonstrates the ability to modulate conductance and perform matrix-vector multiplication using polarization as a parameter. This concept can be generalized to other materials and has potential in various applications.
Article
Multidisciplinary Sciences
Oleg V. Minin, Igor V. Minin, Yinghui Cao
Summary: This study demonstrates the effective generation of tunable bending light beams, called time-PH beams, using freezing water droplets. The key properties of these beams can be flexibly modified by changing the positions and curvature of the water-ice interface inside the droplet. This research has potential applications in various fields.
SCIENTIFIC REPORTS
(2023)
Article
Chemistry, Physical
J. Cwik, Y. Koshkid'ko, K. Nenkov, E. Tereshina-Chitrova, N. Kolchugina
Summary: The study focused on the magnetic entropy change and thermodynamic properties of polycrystalline pseudo-binary Tb1-xErxNi2 solid solutions, with emphasis on Er substitution for Tb causing changes in crystal structure. It was found that the substitution of Er for Tb resulted in a decrease in the ordering temperature of the pseudo-binary compounds, leading to an increase in the maximum magnetic entropy change.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Chemistry, Physical
Jiong Wang, Dongyu Cui, Yi Kong, Luming Shen
Summary: The study utilizes first-principles calculations to observe unusual force constants in crystalline GeTe and Sb2Te3, highlighting the impact of weak and negative force constants on triggering the collapse of long-range order. Additionally, molecular dynamic simulations reveal the potential amorphization of Sb2Te3 through local bond distortions, offering insights for designing components and devices with lower energy consumption based on phase change materials.
Article
Materials Science, Multidisciplinary
Akash Surampalli, Ramon Egli, Deepak Prajapat, Carlo Meneghini, V. Raghavendra Reddy
Summary: BaSn0.15Ti0.85O3 exhibits diffuse phase transition and reentrant behavior near room temperature, along with frequency dispersion and decrease in remanent polarization. The relaxor nature in the system is found responsible for the reentrant behavior, supported by the analysis of first-order reversal curves and local probe techniques.
Article
Materials Science, Multidisciplinary
F. Guillou, H. Yibole, B. Narsu, V. Hardy
Summary: In this study, the volume-preserving transition behavior in the Fe2P material system was experimentally investigated, revealing a significant correlation between the discontinuity in cell parameters and transition entropy change. The findings provide a foundation for systematizing the properties of first-order magnetic transitions (FOMT) in the Fe2P materials system and demonstrate the crucial role of deformation in volume-preserving FOMT.
RESULTS IN PHYSICS
(2023)
Article
Physics, Applied
Fangqi Chen, Yang Liu, Xiaojie Liu, Yi Zheng
Summary: Conventional thermal emission relies on micro/nanostructures to achieve spectral selectivity, but lacks flexibility in terms of thermal emissivity. In this Letter, we propose a multistate multilayered structure using phase change materials, which offers tunable spectra in the mid-infrared range. The structure is lithography-free and industrially scalable, showing great potential for programmable photonics and thermal sensors.
APPLIED PHYSICS LETTERS
(2023)
Article
Optics
Ningning Wang, Tiantian Li, Boshu Sun, Zi Wang, Linjie Zhou, Tingyi Gu
Summary: The focusing length of a silicon photonic metalens can be switched between positive and negative values by a fixed geometric design and homogeneous change of Indium Selenide (In2Se3). This unique functionality is enabled by the fact that the silicon's refractive index is in the middle of the two convertible states in the optical phase change material. The metasurface design is foundry compatible and feasible for implementing nonvolatile adaptive transformation optic systems on-chip.
Article
Materials Science, Multidisciplinary
Yuta Saito, Kirill V. Mitrofanov, Kotaro Makino, Paul Fons, Alexander V. Kolobov, Junji Tominaga, Fumihiko Uesugi, Masaki Takeguchi
Summary: Chalcogenide materials, specifically Bi-Te binary alloys, are being explored as alternative candidates for superlattice or interfacial phase-change memory, showing promising potential for memory applications and potential for novel functional electronic devices.
PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS
(2021)
Article
Materials Science, Multidisciplinary
Paul Fons, Alexander V. Kolobov, Yuta Saito
Summary: PCM is a type of nonvolatile electrical memory based upon the local structure of chalcogenide compounds, while iPCM is a form of PCM that greatly improves energy efficiency and may switch between two crystalline states. The effect of electrical fields on proposed iPCM structures varies, with a dilation in the vdW gap observed in all structures possibly facilitating the proposed switching mechanisms.
PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS
(2021)
Article
Materials Science, Multidisciplinary
Alexander V. Kolobov, Paul Fons, Yuta Saito
Summary: This study investigated the surface states of the topological insulator Sb2Te3 and their implications for practical applications in planar devices and memory cells.
PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS
(2021)
Article
Physics, Multidisciplinary
Yuta Komori, Yuta Saito, Paul Fons, Muneaki Hase
Summary: In this study, ultrafast phonon dynamics in the Bi1-xSbx alloy system were investigated using a reflective femtosecond pump-probe technique. It was found that the frequencies and relaxation times of coherent optical phonons were significantly influenced by the Sb composition x, with minor contributions from electron-phonon scattering in a Weyl-semimetal phase.
NEW JOURNAL OF PHYSICS
(2021)
Article
Multidisciplinary Sciences
Yuta Saito, Shogo Hatayama, Yi Shuang, Paul Fons, Alexander V. Kolobov, Yuji Sutou
Summary: The study demonstrates a dimensional transformation in chemical bonding from a randomly bonded three-dimensional disordered amorphous phase to a 2D bonded vdW crystalline phase, as well as the emergence of a counterintuitive metastable quasi-layered state during crystallization.
SCIENTIFIC REPORTS
(2021)
Article
Chemistry, Physical
Yi Shuang, Shogo Hatayama, Yuta Saito, Paul Fons, Alexander Kolobov, Daisuke Ando, Yuji Sutou
Summary: This study investigates the impact of nitrogen doping on the structure and electrical properties of Cr2Ge2Te6 phase-change memory materials. It is found that nitrogen doping inhibits the formation of Cr nanoclusters, leading to a decrease in resistivity change upon the amorphous to crystalline phase transition.
APPLIED SURFACE SCIENCE
(2021)
Article
Chemistry, Physical
M. Krbal, A. Kolobov, M. Hanfland, P. Fons
Summary: Comparison between the crystallization of as-deposited and pressure-induced amorphous phases of Ge2Sb2Te5 under different pressures revealed that the pressure-induced amorphous phase crystallizes at lower temperatures than its as-deposited counterpart, and the crystallization temperature of pressure-induced amorphous Ge2Sb2Te5 increases with pressure. These results demonstrate that differences in nanoscale ordering in amorphous phases significantly influence crystallization and will guide the insightful development of phase-change devices.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Materials Science, Multidisciplinary
Shogo Hatayama, Keisuke Kobayashi, Yuta Saito, Paul Fons, Yi Shuang, Shunsuke Mori, Alexander V. Kolobov, Yuji Sutou
Summary: This study investigates the impact of Cr content on electrical properties, finding that the increase in carrier density is correlated with the extent of Cr clusters, suggesting that hole carriers likely originate from Cr clusters. The increased concentration of Cr clusters also results in a shift of the valence band edge towards the Fermi level and a decrease in the optical band gap. Results indicate that Cr clusters play a crucial role in determining the electrical properties of amorphous CrGT, and adjusting film composition is an effective way to optimize device properties for nonvolatile memory applications.
PHYSICAL REVIEW MATERIALS
(2021)
Article
Physics, Applied
Milos Krbal, Alexander V. Kolobov, Paul Fons, Yuta Saito, George Belev, Safa Kasap
Summary: This study investigates the structural transformation from an amorphous phase to a one-dimensional vdW crystal and identifies a unique feature associated with vdW bonds using x-ray absorption spectroscopy. The researchers believe that this approach can be applied to study other one-dimensional vdW solids.
APPLIED PHYSICS LETTERS
(2022)
Article
Engineering, Electrical & Electronic
Yuta Saito, Misako Morota, Kotaro Makino, Junji Tominaga, Alexander Kolobov, Paul Fons
Summary: This paper reviews recent developments in sputter growth of chalcogenide thin films for phase-change memory applications, focusing on highly oriented Sb2Te3. The optimization of sputtering conditions enables growth on various substrates, with the same techniques applicable for deposition of similar materials. Meeting the demand for nonvolatile memory and other electronic devices relies on the fabrication of high-quality thin films through industry-friendly methods.
MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING
(2021)
Article
Materials Science, Multidisciplinary
Takumi Fukuda, Ryota Kaburauchi, Yuta Saito, Kotaro Makino, Paul Fons, Keiji Ueno, Muneaki Hase
Summary: In this study, coherent phonon spectroscopy is used to investigate the relationship between structural phase transitions and photo-thermal effects in polymorphic MoTe2 single crystals. The results show that increasing excitation density leads to tellurium segregation, but no structural phase transition is observed among the polymorphs of MoTe2. However, higher photon-energy excitation is found to suppress tellurium segregation.
PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS
(2022)
Article
Chemistry, Physical
Roman Svoboda, Lenka Durcikova, Jan Prikryl, Keisuke Hamano, Paul J. Fons, Milos Krbal
Summary: The formation kinetics of 2D-layered InSe crystalline phase in thin amorphous InSe films was investigated using various analytical techniques. The results showed that the formation process involves two steps, with the reorganization of the amorphous phase followed by the formation of the crystalline phase. The presence of defects and imperfections in the films was found to significantly slow down both processes. A two-step approach for the preparation of highly layered flexible 2D InSe ceramics is suggested.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Chemistry, Multidisciplinary
Yuta Saito, Shogo Hatayama, Wen Hsin Chang, Naoya Okada, Toshifumi Irisawa, Fumihiko Uesugi, Masaki Takeguchi, Yuji Sutou, Paul Fons
Summary: This article reports on the growth of thin crystalline films of the metastable phase GeTe2. Direct observation by transmission electron microscopy revealed a Te-Ge-Te stacking with van der Waals gaps. Moreover, electrical and optical measurements demonstrated that the films exhibited semiconducting properties suitable for electronic applications. Feasibility studies involving device structures also highlighted the potential of GeTe2 as an electronic material.
MATERIALS HORIZONS
(2023)
Article
Materials Science, Multidisciplinary
Shogo Hatayama, Yuta Saito, Kotaro Makino, Noriyuki Uchida, Yi Shuang, Shunsuke Mori, Yuji Sutou, Milos Krbal, Paul Fons
Summary: This study annealed amorphous Mo-Te films to obtain crystalline phase, while eliminating excess Te through sublimation. It also investigated the crystallization mechanism and developed a method for large-area MoTe2 film deposition.
JOURNAL OF MATERIALS CHEMISTRY C
(2022)