Article
Chemistry, Multidisciplinary
Yiwei Li, Shihao Zhang, Fanqiang Chen, Liyang Wei, Zonglin Zhang, Hanbo Xiao, Han Gao, Moyu Chen, Shijun Liang, Ding Pei, Lixuan Xu, Kenji Watanabe, Takashi Taniguchi, Lexian Yang, Feng Miao, Jianpeng Liu, Bin Cheng, Meixiao Wang, Yulin Chen, Zhongkai Liu
Summary: Magic-angle twisted trilayer graphene (MATTG) has shown rich and unique properties, including superconductivity and distinct band structure. Experimental measurements reveal the coexistence of different bands in MATTG, which is crucial for further understanding its unconventional superconductivity.
ADVANCED MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
Sung Ju Hong, Donglei Wang, Dirk Wulferding, Peter Lemmens, Rolf J. Haug
Summary: The magnetotransport properties of single- and double-rhombohedral trilayer graphene (TLG) are investigated. By folding single TLG, a double TLG with a twist angle of 4° is obtained. Raman spectroscopy confirms the ABC stacking order and interlayer coupling. The Landau fan diagram shows overlapped features of each constituent TLG, suggesting weak interlayer coupling.
Article
Multidisciplinary Sciences
Hyunjin Kim, Youngjoon Choi, Cyprian Lewandowski, Alex Thomson, Yiran Zhang, Robert Polski, Kenji Watanabe, Takashi Taniguchi, Jason Alicea, Stevan Nadj-Perge
Summary: Magic-angle twisted trilayer graphene (MATTG) is a moire material that exhibits strong electronic correlations and unconventional superconductivity. In this study, high-resolution scanning tunnelling microscopy and spectroscopy are used to investigate MATTG. Extensive regions of atomic reconstruction with mirror-symmetric stacking are observed, showing symmetry-breaking electronic transitions and doping-dependent band-structure deformations. Superconductivity is observed as pronounced dips in the tunnelling conductance at the Fermi level, accompanied by coherence peaks that become gradually suppressed at elevated temperatures and magnetic fields. The observed conductance evolution with doping suggests a transition from a gapped superconductor to a nodal superconductor, and the presence of peak-dip-hump structures indicates strong coupling to bosonic modes of MATTG.
Article
Multidisciplinary Sciences
Simon Turkel, Joshua Swann, Ziyan Zhu, Maine Christos, K. Watanabe, T. Taniguchi, Subir Sachdev, Mathias S. Scheurer, Efthimios Kaxiras, Cory R. Dean, Abhay N. Pasupathy
Summary: The magic-angle twisted trilayer graphene has shown a potential for engineering strongly correlated flat bands. Using low-temperature scanning tunneling microscopy, researchers have observed a strong reconstruction of the moire lattice in real trilayer samples, leading to the formation of localized twist-angle faults. These localized regions exhibit different electronic structures compared to the background regions, resulting in a doping-dependent, spatially granular electronic landscape.
Editorial Material
Chemistry, Physical
Matthew Yankowitz
Summary: A new spectroscopic technique exploits overlapping electronic bands to investigate the highly correlated states of magic-angle twisted trilayer graphene.
Article
Multidisciplinary Sciences
Jeong Min Park, Yuan Cao, Kenji Watanabe, Takashi Taniguchi, Pablo Jarillo-Herrero
Summary: Moire superlattices have become a platform for studying correlated physics and superconductivity with unprecedented tunability. This study on magic-angle twisted trilayer graphene reveals a better tunability of electronic structure and superconducting properties than magic-angle twisted bilayer graphene, with implications for the understanding of strongly coupled superconductivity. The results suggest that the system can be electrically tuned close to the crossover to a two-dimensional Bose-Einstein condensate, indicating the potential for revolutionizing applications of superconductivity.
Article
Physics, Multidisciplinary
Xiaoxue Liu, Naiyuan James Zhang, K. Watanabe, T. Taniguchi, J. I. A. Li
Summary: The discovery of magic-angle twisted trilayer graphene and its integration into a double-layer structure provides important insights into the properties and stability of the superconducting phase. The findings also contribute to the development of theoretical models aiming to understand the nature of superconductivity.
Article
Chemistry, Physical
Cheng Shen, Patrick J. Ledwith, Kenji Watanabe, Takashi Taniguchi, Eslam Khalaf, Ashvin Vishwanath, Dmitri K. Efetov
Summary: Magic-angle twisted trilayer graphene (MATTG) has flat electronic bands and exhibits correlated quantum phases. A spectroscopy technique is demonstrated in this work to dissociate intertwined bands and quantify the energy gaps and Chern numbers C of the correlated states in MATTG. Hard correlated gaps with C = 0 at integer moiré unit cell fillings and charge density wave states originating from van Hove singularities at fractional fillings are uncovered. Displacement-field-driven first-order phase transitions at charge neutrality and v = 2 are also demonstrated. Overall, these properties establish a diverse electrically tunable phase diagram of MATTG.
Article
Multidisciplinary Sciences
Zhen Ma, Shuai Li, Ya-Wen Zheng, Meng-Meng Xiao, Hua Jiang, Jin-Hua Gao, X. C. Xie
Summary: Twisted trilayer graphene is a simple realistic system with flat bands and nontrivial topology, making it an ideal platform for studying strongly correlated physics. The band structures of twisted TLG are influenced by the twist angle and perpendicular electric field, resulting in unique correlated states compared to other graphene structures.
Article
Physics, Multidisciplinary
Maine Christos, Subir Sachdev, Mathias S. Scheurer
Summary: Motivated by recent experiments in twisted-trilayer graphene, this study investigates the effects of interactions and superconductivity in this system close to the magic angle. The researchers identify ground states at different filling fractions and construct a phase diagram. They also study the superconducting properties of these states and find triplet pairing dominance in the experimentally relevant regime. The results have implications for future experiments and theoretical work in this field.
Article
Materials Science, Multidisciplinary
Vo Tien Phong, Pierre A. Pantaleon, Tommaso Cea, Francisco Guinea
Summary: We studied the symmetries of twisted trilayer graphene's band structure under various extrinsic perturbations, and found that the electronic structure is modified by long-range electron-electron interactions in a similar way to twisted bilayer graphene. Electron pairing due to long-wavelength charge fluctuations coupled via the Coulomb interaction and additionally mediated by longitudinal acoustic phonons leads to superconducting phases with different symmetries, with critical temperatures up to a few Kelvin for realistic choices of parameters.
Article
Materials Science, Multidisciplinary
Ammon Fischer, Zachary A. H. Goodwin, Arash A. Mostofi, Johannes Lischner, Dante M. Kennes, Lennart Klebl
Summary: Magic-angle twisted trilayer graphene is a highly tunable platform for studying correlated phases of matter. In this research, we find that spin fluctuations play an important role in superconductivity, and we discover new features in the phase diagram of the superconducting state.
NPJ QUANTUM MATERIALS
(2022)
Article
Physics, Multidisciplinary
Wei Qin, Allan H. MacDonald
Summary: Recent research has shown that superconductivity in magic-angle twisted trilayer graphene can survive in in-plane magnetic fields well beyond the Pauli limit, unlike magic-angle twisted bilayer graphene. The difference is attributed to the symmetry and relative displacements present in trilayers, which are not under experimental control at present. An gate electric field can break the symmetry and limit the in-plane critical magnetic field.
PHYSICAL REVIEW LETTERS
(2021)
Article
Materials Science, Multidisciplinary
Adrian Pena
Summary: This paper investigates the scattering of electrons on a twisted light-driven graphene quantum dot, revealing the possibility of trapping incident electrons inside the dot for finite periods of time under certain scattering conditions. It also predicts that trapping times can be controlled using twisted light irradiation. The study was conducted for a frequency of the twisted light within the infrared spectrum.
Article
Physics, Applied
Sanghyun Kim, Donghyeon Lee, Binbin Wang, Shang-Jie Yu, Kenji Watanabe, Takashi Taniguchi, Jonathan A. Fan, Jiamin Xue, Kayoung Lee
Summary: A Raman spectroscopic study of twisted artificial trilayer graphene (3LG) reveals distinctive 2D peak characteristics when the twist angle is greater than 5 degrees, and shows similarities to natural Bernal-stacked 3LG in non-twisted cases, indicating a thermodynamically stable state. Additionally, slightly twisted 3LG exhibits coexisting Bernal-stacked (ABA) and rhombohedral (ABC) domains.
APPLIED PHYSICS LETTERS
(2021)
Article
Chemistry, Multidisciplinary
Mohammad Amini, Orlando J. Silveira, Viliam Vano, Jose L. Lado, Adam S. Foster, Peter Liljeroth, Shawulienu Kezilebieke
Summary: 2D ferroelectric materials are promising for electrical control of quantum states, and can influence the quantum states of deposited molecules due to their 2D nature. This study reports electrically controllable molecular states in phthalocyanine molecules adsorbed on monolayer ferroelectric material SnTe. The strain and ferroelectric order in SnTe create a transition between two distinct orbital orders in the adsorbed phthalocyanine molecules. The polarization of the ferroelectric domain can be manipulated electrically, providing a starting point for ferroelectrically switchable molecular orbital ordering and ultimately, electrical control of molecular magnetism.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Adolfo O. Fumega, Jose L. Lado
Summary: In this work, it is demonstrated that AB bilayer graphene encapsulated in MoTe2 acts as a valley valve that displays a switchable built-in topological gap, leading to ferroelectrically driven topological channels.
Article
Chemistry, Multidisciplinary
Somesh Chandra Ganguli, Markus Aapro, Shawulienu Kezilebieke, Mohammad Amini, Jose L. Lado, Peter Liljeroth
Summary: Two-dimensional magnetic materials provide a platform to study and design magnonic excitations. This study demonstrates the emergence of moire magnon excitations in monolayer CrBr3, resulting from the interplay of spin-excitations and the moire pattern. The existence of moire magnons is confirmed through inelastic quasiparticle interference, which shows a dispersion pattern correlated with the moire length scale.
Article
Physics, Multidisciplinary
Sharadh Jois, Jose L. Lado, Genda Gu, Qiang Li, Ji Ung Lee
Summary: Scattering processes in quantum materials lead to resonances in electronic transport, such as confined modes, Andreev states, and Yu-Shiba-Rusinov states. In most cases, these resonances are driven by a single scattering mechanism. This study demonstrates the appearance of resonances due to the combination of two simultaneous scattering mechanisms in graphene p-n junctions and superconductivity. The experimental measurements and quantum transport calculations support the existence of these resonances, which have potential implications for graphene-based Josephson junctions.
PHYSICAL REVIEW LETTERS
(2023)
Article
Physics, Multidisciplinary
Guangze Chen, Fei Song, Jose L. Lado
Summary: The computation of spectral functions in a non-Hermitian many-body system is a challenging task, but this article proposes a numerical approach to address this problem. By utilizing the kernel polynomial method and the matrix-product state formalism, the local spectral functions of a non-Hermitian many-body Hamiltonian can be efficiently computed. The results demonstrate that the algorithm accurately captures the topological spin excitations and line gap topology in non-Hermitian spin models, even in the presence of the non-Hermitian skin effect.
PHYSICAL REVIEW LETTERS
(2023)
Article
Materials Science, Multidisciplinary
Adolfo O. Fumega, Jose L. Lado
Summary: Twisted chromium trihalide bilayers exhibit the emergence of multiferroic order driven by the moire pattern. The competition between stacking-dependent interlayer magnetic exchange and magnetic anisotropy generates a spin texture in the moire supercell, leading to a non-collinear magnetic state that gives rise to an electric polarization and local ferroelectric order. Among the stoichiometric trihalides, twisted CrBr3 bilayers show the strongest multiferroic order and a strong magnetoelectric coupling, allowing for the electric generation and control of magnetic skyrmions.
Article
Materials Science, Multidisciplinary
Andrew Cole, Alenna Streeter, Adolfo O. Fumega, Xiaohan Yao, Zhi-Cheng Wang, Erxi Feng, Huibo Cao, Jose L. Lado, Stephen E. Nagler, Fazel Tafti
Summary: Recently, mixed halide chemistry has been used to adjust the intrinsic magnetic properties of transition-metal halides, which belong to the largest family of magnetic van der Waals materials. Previous studies have shown that the strength of exchange interactions and the critical temperature can be smoothly adjusted by altering the halide composition for a given ground state. In this study, we demonstrate that the ground state itself can be changed by a small change in halide composition in FeCl(3-)xBr(x). Neutron scattering reveals a transition from spiral order in FeCl3 to A-type antiferromagnetic order in FeBr3, accompanied by a threefold increase in the Neel temperature and a sign change in the Weiss temperature at x = 0.08 (corresponding to 3% bromine doping). First-principles calculations indicate that a delicate balance between nearest and next-nearest neighbor interactions is responsible for this transition. These findings highlight the ability to control competing interactions and manipulate the ground state of a spiral spin liquid system by varying the halide composition.
PHYSICAL REVIEW MATERIALS
(2023)
Article
Physics, Multidisciplinary
Faluke Aikebaier, Teemu Ojanen, Jose L. Lado
Summary: We propose a strategy to obtain the correlation entropy of electronic systems solely from a set of local measurements. By combining local particle-particle and density-density correlations with a neural-network algorithm, the correlation entropy can be accurately predicted.
SCIPOST PHYSICS CORE
(2023)
Article
Chemistry, Multidisciplinary
Viliam Vano, Somesh Chandra Ganguli, Mohammad Amini, Linghao Yan, Maryam Khosravian, Guangze Chen, Shawulienu Kezilebieke, Jose L. Lado, Peter Liljeroth
Summary: Unconventional superconductors, particularly nodal superconductors, have been a focus in modern quantum materials research. This study demonstrates the existence of nodal superconductivity in pristine monolayer 1H-TaS2 using low-temperature scanning tunneling microscopy (STM) and spectroscopy (STS) experiments. It is also found that non-magnetic disorder can drive the nodal state to a conventional gapped s-wave state, and many-body excitations emerge near the gap edge, indicating a potential unconventional pairing mechanism.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Wonhee Ko, Sang Yong Song, Jiaqiang Yan, Jose L. Lado, Petro Maksymovych
Summary: This study introduces the unique capability of tunneling Andreev reflection (TAR) to probe unconventional pairing symmetry in low-dimensional unconventional superconductors. By studying the paradigmatic FeSe superconductor, we provide direct evidence of sign-changing order parameter, reveal the existence of two superconducting gaps, and confirm the local suppression of superconductivity along the nematic twin boundary. These findings enable new atomic-scale insight into microscopic, inhomogeneous, and interfacial properties of emerging quantum materials.
Article
Physics, Multidisciplinary
Robert Drost, Shawulienu Kezilebieke, Jose L. Lado, Peter Liljeroth
Summary: Quantum magnets have proven to be a powerful tool for studying complex quantum many-body phenomena. In this study, researchers engineered a minimal quantum magnet using organic molecules and observed the emergence of dispersive triplon excitations in one- and two-dimensional assemblies using scanning tunneling microscopy and spectroscopy. This is the first demonstration of dispersive triplon excitations from a real-space measurement.
PHYSICAL REVIEW LETTERS
(2023)
Article
Physics, Multidisciplinary
Sharareh Sayyad, Jose L. Lado
Summary: Many-body interactions lead to the emergence of exotic phases in Hermitian physics. However, treating many-body effects in non-Hermitian physics remains a challenging problem due to their complexity. In this study, we present exact and numerical phase diagrams for non-Hermitian interacting Kitaev chains. We establish the exact phase boundaries for the dimerized Kitaev-Hubbard chain with complex-valued Hubbard interactions and investigate the persistence of non-Hermitian topological degeneracy beyond the solvable regime.
PHYSICAL REVIEW RESEARCH
(2023)
Article
Materials Science, Multidisciplinary
Valerii Kachin, Teemu Ojanen, Jose L. Lado, Timo Hyart
Summary: In two-dimensional superconductors, electron-electron interactions can enhance or reduce the topological energy gaps and cause topological phase transitions. However, statistically, the interactions have no effect on the realized Chern numbers and typical magnitudes of the topological gaps. The interactions substantially increase the likelihood of the largest topological gaps in the tails of the energy gap distribution in comparison to the noninteracting case.
Article
Physics, Multidisciplinary
Timo Hyart, J. L. Lado
Summary: This study demonstrates that non-Hermitian many-body topological modes can be achieved in a quantum dot chain through gate-tunable modulation of dissipation. The results show that these topological modes are robust even in the presence of strong interactions, highlighting the resilience of non-Hermitian topology to electronic interactions.
PHYSICAL REVIEW RESEARCH
(2022)
Article
Physics, Multidisciplinary
Sophie Beck, Alexander Hampel, Manuel Zingl, Carsten Timm, Aline Ramires
Summary: Uniaxial-strain experiments have been used to study unconventional phases of electronic matter. In this study, the authors propose a combination of superconducting fitness analysis and density functional theory calculations to understand the effects of strain on complex multiorbital quantum materials. They apply this framework to Sr2RuO4 and find unique strain-dependent signatures in the superconducting state, which agree with recent observations.
PHYSICAL REVIEW RESEARCH
(2022)
