Article
Physics, Multidisciplinary
Yeyang Zhang, Ryuichi Shindou
Summary: In this study, we propose a mechanism for dissipationless spin-charge conversion using excitonic pseudospin superfluid in an electron-hole double-layer system. By lifting the degeneracy of exciton levels through magnetic exchange fields, we achieve spin-charge coupled superflow.
PHYSICAL REVIEW LETTERS
(2022)
Article
Chemistry, Physical
Jiwon Jeon, Youngjae Kim, J. D. Lee
Summary: Pseudospin, a fundamental quantum number in graphene, can be changed by the rotation of phonons. By observing the phonon satellite accompanying the linearly pumped electron to the upper Dirac cone, we found that pseudospin exhibits rotation, nonzero angular momentum, and Berry curvature. We also identified the phonon responsible for pseudospin rotation as an elliptically polarized phonon, which can induce chiral phonon excitation without circularly polarized pumping.
Article
Physics, Multidisciplinary
Saber Rostamzadeh, Mustafa Sarisaman
Summary: This study investigates the nonequilibrium transport of carriers in both standard graphene and semi-Dirac graphene systems, finding that lattice modifications affect carrier diffusion and introducing the concept of pseudospin index in particle current and magnetoelectric effect. The study suggests that pseudospin-charge coupling can be used to design a pseudospin filter.
NEW JOURNAL OF PHYSICS
(2022)
Article
Materials Science, Multidisciplinary
Zheng Liu, Chao Zhang, J. C. Cao
Summary: The study investigates the magic angles for superconductivity in twisted bilayer graphene using a continuum model, revealing that the system can be equivalently represented by a dynamical system composed of three parts of effective interactions. The research also shows the physical significance of various components within the system, such as the effective Rashba effect, interlayer electric field, and geometric curvature on a vector bundle.
Article
Physics, Multidisciplinary
Chunli Huang, Nemin Wei, Wei Qin, Allan H. MacDonald
Summary: The study presents a theory of superconductivity in twisted bilayer graphene, where attraction is generated between electrons on the same honeycomb sublattice near a sublattice polarization instability, leading to spin-polarized valley singlet Cooper pairs. Superconductivity occurs over a wide range of filling fraction, and can be suppressed by controlling sublattice polarizability or moire band filling to favor valley polarization.
PHYSICAL REVIEW LETTERS
(2022)
Article
Chemistry, Multidisciplinary
Yu Zhang, Ying Su, Lin He
Summary: Vortices in graphene induced by single carbon defects can be considered as atomic-scale vortices mediated by pseudospin, with angular momenta of +2 and -2. Quantum interference measurements show that these vortices cancel each other, resulting in zero total angular momentum or aggregate chirality similar to a single vortex of the majority.
Article
Multidisciplinary Sciences
Lihuan Sun, Louk Rademaker, Diego Mauro, Alessandro Scarfato, Arpad Pasztor, Ignacio Gutierrez-Lezama, Zhe Wang, Jose Martinez-Castro, Alberto F. Morpurgo, Christoph Renner
Summary: This study uses scanning tunneling microscopy to image backscattering in graphene/tungsten selenide heterostructures and quantitatively determine the strength of spin-orbit coupling (SOC). The results show that the strength of SOC is one order of magnitude larger than what theory predicted, but in agreement with previous transport experiments.
NATURE COMMUNICATIONS
(2023)
Article
Chemistry, Physical
Yun Ni, Jia Li, Wei Tao, Hao Ding, Rui-Xue Li
Summary: This paper studied the transport properties of defected ZGNR with a graphene nanobubble through first-principles quantum transport calculations. When the nanobubble is intact and located at the center, the spin polarization and magnetoresistance tend to decrease at low bias voltages, while when the nanobubble is split and located at the edge, all transport properties are significantly affected and altered. New results obtained from the device include the negative differential resistance effect and the pure thermal-induced spin-current.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2021)
Article
Chemistry, Multidisciplinary
Erick Arguello Cruz, Pedro Ducos, Zhaoli Gao, Alan T. Charlie Johnson, Dario Niebieskikwiat
Summary: In this study, the effect of ferromagnetic nickel nanoparticles on the magnetotransport properties of chemical-vapor-deposited graphene was characterized. It was found that these nanoparticles greatly suppressed the zero-field peak of resistivity caused by weak localization and enhanced the high-field magnetoresistance. The interaction between the graphene and the nickel nanoparticles was attributed to a local exchange coupling, which did not affect the intrinsic transport parameters of graphene, indicating that the changes in magnetotransport properties were purely magnetic in origin.
Article
Nanoscience & Nanotechnology
Yutao Li, Scott Dietrich, Carlos Forsythe, Takashi Taniguchi, Kenji Watanabe, Pilkyung Moon, Cory R. Dean
Summary: By utilizing dielectric patterning to subject graphene to a one-dimensional electrostatic superlattice, multiple Dirac cones are observed, demonstrating the ability to induce tunable anisotropy in high-mobility two-dimensional materials. This offers a new approach to engineering flat energy bands where electron interactions can lead to emergent properties, which is desired for novel electronic and optical applications.
NATURE NANOTECHNOLOGY
(2021)
Article
Chemistry, Physical
Liwen Zhang, Jun Chen, Lei Zhang, Fuming Xu, Liantuan Xiao, Suotang Jia
Summary: Graphene with micrometer spin relaxation length presents promising potential in spintronics, but efficient spin injection remains a challenge. Generating spin current in ZGNR via photogalvanic effect provides a novel approach to achieve spin injection without accompanying charge current, and the spin current generation and polarization can be controlled through a dual gate system.
Article
Multidisciplinary Sciences
Na Xin, James Lourembam, Piranavan Kumaravadivel, A. E. Kazantsev, Zefei Wu, Ciaran Mullan, Julien Barrier, Alexandra A. Geim, I. V. Grigorieva, A. Mishchenko, A. Principi, V. I. Fal'ko, L. A. Ponomarenko, A. K. Geim, Alexey I. Berdyugin
Summary: The most distinctive feature of graphene is its electronic spectrum, in which the Dirac point is located. At low temperatures, the intrinsic behavior of this spectrum is often hidden by charge inhomogeneity, but thermal excitations can overcome the disorder at higher temperatures and create an electron-hole plasma. The behavior of this plasma in magnetic fields is not well understood at present.
Article
Materials Science, Multidisciplinary
Benjamin Sanvee, Jakob Schluck, Mihai Cerchez, Dominique Mailly, Hans W. Schumacher, Klaus Pierz, Thomas Heinzel, Juergen Horbach
Summary: Using experiment and simulation, we study the magnetotransport in a two-dimensional disordered Lorentz gas with circular obstacles. We find that for high obstacle density, a linear relationship between Hall resistance and magnetic field is observed only at very low magnetic fields, with a Hall coefficient that does not accurately reflect the carrier density. At larger magnetic fields, nonlinearity of the Hall resistance due to classical memory effects is observed.
Article
Materials Science, Multidisciplinary
Ke Wang, T. A. Sedrakyan
Summary: Perpendicular magnetic field introduces an anomalous interaction correction to the static conductivity of doped graphene, leading to a proportional relationship between magnetoresistance and inverse temperature. This behavior originates from field-induced breaking of symmetry.
Article
Chemistry, Physical
Mohammad Z. Rahman, Partha Maity, Omar F. Mohammed, Jorge Gascon
Summary: Compared to crystalline carbon nitride, disordered carbon nitride performs poorly as a hydrogen production photocatalyst. The presence of reduced graphene oxide enhances its photocatalytic activity by suppressing recombination and enabling faster separation of charge carriers. The findings provide a proof-of-concept for overcoming recombination problems in disordered carbon nitride.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2022)
Article
Chemistry, Multidisciplinary
Rishi Shivhare, Gareth John Moore, Andreas Hofacker, Sebastian Hutsch, Yufei Zhong, Mike Hambsch, Tim Erdmann, Anton Kiriy, Stefan C. B. Mannsfeld, Frank Ortmann, Natalie Banerji
Summary: A study of a blend of low-optical-gap diketopyrrolopyrrole polymer and a fullerene derivative with near-zero driving force for electron transfer was conducted using femtosecond transient absorption and electroabsorption spectroscopy. Ultrafast electron transfer was observed, along with significant charge recombination and short excited and CT state lifetimes. Density functional theory calculations confirmed the effects of back-transfer and CT hybridization on charge recombination, while simulations showed potential strategies to increase free charge yield despite short lifetimes.
ADVANCED MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
Armando Pezo, Zeila Zanolli, Nils Wittemeier, Pablo Ordejon, Adalberto Fazzio, Stephan Roche, Jose H. Garcia
Summary: Proximity effects between layered materials lead to novel quantum transport phenomena, and the nature and strength of these effects can be modulated by changing crystalline and interfacial symmetries, providing opportunities for optimizing physical properties relevant for innovative applications.
Article
Chemistry, Multidisciplinary
Isaac Alcon, Gaetano Calogero, Nick Papior, Aleandro Antidormi, Kenan Song, Aron W. Cummings, Mads Brandbyge, Stephan Roche
Summary: Recent progress in on-surface synthesis and characterization of nanomaterials is enabling the creation of new carbon allotropes, such as the biphenylene network (BPN), which exhibits unusual metallic conductivity and potential device functionalities in nanoelectronics and spintronics.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Article
Chemistry, Multidisciplinary
Mustafa Neset Cinar, Aleandro Antidormi, Viet-Hung Nguyen, Alessandro Kovtun, Samuel Lara-Avila, Andrea Liscio, Jean-Christophe Charlier, Stephan Roche, Haldun Sevincli
Summary: A study reveals the charge conduction laws in multilayer reduced graphene oxides (rGO), showing that interlayer interaction and film thickness have effects on diffusion. In contacted films, conduction is predominantly driven by interlayer hopping when the mean free path becomes shorter than the channel length. These findings contribute to the optimization of graphene-based composites with improved electrical conduction.
Article
Nanoscience & Nanotechnology
Giuseppe Bevilacqua, Alessandro Cresti, Giuseppe Grosso, Guido Menichetti, Giuseppe Pastori Parravicini
Summary: Based on the Landauer-Buttiker theory, this study explores the thermal regimes of nanoscale systems with an energy-peaked transmission function. It identifies the operation regions where the system acts as an energy pump or heat pump, or operates in dissipative modes. The study demonstrates the presence of quantum bounds for thermoelectric quantities and their dependence on the position of the transmission peak.
PHYSICA E-LOW-DIMENSIONAL SYSTEMS & NANOSTRUCTURES
(2022)
Article
Materials Science, Multidisciplinary
Youkyung Seo, Soo Yeon Kim, Yeeun Kim, Chulmin Kim, Byung Chul Lee, Yoon Hee Park, Minji Chae, Youjin Hong, Min Kyung Seong, Changhyun Ko, Alessandro Cresti, Christoforos Theodorou, Gyu Tae Kim, Min-Kyu Joo
Summary: The presence of surface adsorbates and oxidation in 2D multilayers can significantly affect the carrier density distribution and mobility. We discovered a hidden surface channel in black phosphorus and rhenium disulfide multilayers, caused by ambient adsorbates and surface oxides, which not only alters the carrier density but also suppresses the carrier mobility.
Article
Multidisciplinary Sciences
Hyunsoo Yang, Sergio O. Valenzuela, Mairbek Chshiev, Sebastien Couet, Bernard Dieny, Bruno Dlubak, Albert Fert, Kevin Garello, Matthieu Jamet, Dae-Eun Jeong, Kangho Lee, Taeyoung Lee, Marie-Blandine Martin, Gouri Sankar Kar, Pierre Seneor, Hyeon-Jin Shin, Stephan Roche
Summary: This article provides an overview of the current developments and challenges in regards to MRAM and outlines the opportunities that can arise by incorporating two-dimensional material technologies. The fundamental properties of atomically smooth interfaces, reduced material intermixing, crystal symmetries, and proximity effects are highlighted as key drivers for possible disruptive improvements in MRAM at advanced technology nodes.
Article
Chemistry, Physical
Sebastian Hutsch, Michel Panhans, Frank Ortmann
Summary: This study proposes a new model that combines different modeling methods for charge transport in organic semiconductors. The results show that this model can effectively predict the mobility of organic crystals and identify high-mobility materials using simple predictors.
NPJ COMPUTATIONAL MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
Jakob Lenz, Martin Statz, K. Watanabe, T. Taniguchi, Frank Ortmann, R. Thomas Weitz
Summary: Despite the complex nanostructure, the fundamental mechanism of charge transport through organic polymers is still unclear. In this study, we investigate charge transport at the sub-100 nm lengthscale using single poly(diketopyrrolopyrrole-terthiophene) fiber transistors with two different solid gate dielectrics. The results show near-ideal behavior at room temperature and nonlinear behavior at low temperatures, which can be explained by the formation of multiple quantum dots.
JOURNAL OF PHYSICS-MATERIALS
(2023)
Article
Physics, Mathematical
Haruki Watanabe, Meng Cheng, Yohei Fuji
Summary: Topologically ordered phases in 2 + 1 dimensions are characterized by fractional excitation, topological entanglement, and robust ground state degeneracy without symmetry protection. In this study, an extension of the Kitaev toric code to N level spins is introduced, which realizes topologically ordered phases or symmetry-protected topological phases depending on the model parameters. The unique ground state and nontrivial topological entanglement entropy are explained by the nontrivial translation action permuting anyon species.
JOURNAL OF MATHEMATICAL PHYSICS
(2023)
Article
Physics, Applied
Andres Jenaro Lopez Garcia, Mireille Mouis, Thomas Jalabert, Alessandro Cresti, Gustavo Ardila
Summary: This study investigated the relationship between the electromechanical response of semiconducting piezoelectric nanowires (NWs) and their length. A new mechanism of piezoresponse saturation was identified, which resulted from the combined influence of interface traps and piezoelectric polarization in the depleted NW. The results of this study were in better qualitative agreement with experimental observations compared to existing theories. The finite element method was used to simulate the mechanical, piezoelectric, and semiconductor properties of the NWs, with simulations focusing on uniform ZnO NWs grown along the c-axis. An analytical model was developed to support the analysis and provided trends of saturation length and piezoresponse as a function of NW dimensions, doping level, surface traps density, crystal polarity, and external pressure.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2023)
Article
Chemistry, Multidisciplinary
Rukiya Matsidik, Hartmut Komber, Martin Brinkmann, Karl Sebastian Schellhammer, Frank Ortmann, Michael Sommer
Summary: Efficient organic electronic devices can be fabricated from discrete oligomers, which can be synthesized at gram scale. The properties of these oligomers, including optical, electronic, thermal, and structural properties, depend on their length. The results of this study provide a basis for investigating the length-structure-function relationships of oligomers.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Physics, Multidisciplinary
Michel Panhans, Sebastian Hutsch, Frank Ortmann
Summary: In this study, numerical and analytical quantum approaches are used to investigate the charge transfer dynamics in organic solids. The fading of transient localization and the formation of polarons are revealed in a wide range of vibrational frequencies and temperatures. Three distinct charge transport regimes, including transient localization, Soft Gating, and polaron transport, are identified, and the transitions between these regimes are found to be governed by the correlations between electronic motion and nuclei.
COMMUNICATIONS PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Maximilian F. X. Dorfner, Sebastian Hutsch, Raffaele Borrelli, Maxim F. Gelin, Frank Ortmann
Summary: In this study, we investigate the charge transfer dynamics of photogenerated excitons at the donor-acceptor interface of an organic solar cell blend under the influence of molecular vibrations. By using an effective Hamiltonian and the matrix-product-state ansatz, we provide insight into different mechanisms of charge separation and their relation to the electronic driving energy.
JOURNAL OF PHYSICS-MATERIALS
(2022)
Review
Physics, Applied
Hidekazu Kurebayashi, Jose H. Garcia, Safe Khan, Jairo Sinova, Stephan Roche
Summary: This review focuses on the spintronic properties of layered materials and emphasizes the importance of optimizing chemical interactions and material symmetries to achieve the best performing material design for spin-orbit torque efficiency.
NATURE REVIEWS PHYSICS
(2022)
