Article
Chemistry, Multidisciplinary
Tao Zhang, Chaofeng Gao, Dongdong Liu, Zhuolun Li, Hao Zhang, Mengqi Zhu, Zhenxiao Zhang, Puqin Zhao, Yingchun Cheng, Wei Huang
Summary: In this study, the evolution of van Hove singularities (vHSs) in twisted bilayer graphene (tBLG) under pressure was investigated using Raman spectroscopy. The results show that pressure induces a blue shift of specific spectral bands and tunes their intensity. Additionally, pressure enhances intervalley electron scattering. This study provides insights into the photon-electron-phonon interaction in tBLG and opens up avenues for pressure engineering of vHS in this material.
Article
Physics, Multidisciplinary
Delong Fang, Yunkang Cui
Summary: A theoretical study was conducted on discrete vortex bound states near a vortex core in the presence of a van Hove singularity (VHS) near the Fermi level using the Bogoliubov-de Gennes (BdG) equations. When the VHS is exactly at the Fermi level and in the middle of the band, a zero-energy state and higher-energy states with energy ratios following integer numbers emerge. These discrete vortex bound state peaks undergo splitting behavior when the VHS or Fermi level moves away from the middle of the band, eventually leading to a rearrangement of quantized vortex core states with energy ratios following half-odd-integer numbers.
Article
Multidisciplinary Sciences
Kyungchan Lee, Gunnar F. Lange, Lin-Lin Wang, Brinda Kuthanazhi, Thais Trevisan, Na Hyun Jo, Benjamin Schrunk, Peter P. Orth, Robert-Jan Slager, Paul C. Canfield, Adam Kaminski
Summary: Time reversal symmetric (TRS) invariant topological insulators (TIs) play a paradigmatic role in the field of topological materials, while weak topological insulators (WTIs) are more challenging due to their dependence on translational symmetry and limited topological surface states in specific directions. The discovery of a WTI state in RhBi2 opens up possibilities for novel quantum effects due to its exotic features.
NATURE COMMUNICATIONS
(2021)
Article
Chemistry, Multidisciplinary
Qian Gao, Qimin Yan, Zhenpeng Hu, Lan Chen
Summary: By using first-principles calculations, a bilayer Kagome lattice with multiple van Hove singularities is designed and a novel borophene (BK-borophene) with such lattice is proposed. The BK-borophene is predicted to be energetically, dynamically, thermodynamically, and mechanically stable. The electronic structure hosts both conventional and high-order van Hove singularities in one band.
Article
Materials Science, Multidisciplinary
Armando Consiglio, Tilman Schwemmer, Xianxin Wu, Werner Hanke, Titus Neupert, Ronny Thomale, Giorgio Sangiovanni, Domenico Di Sante
Summary: In this study, the structural and electronic properties of kagome metals AV(3)Sb(5) (A = Cs, K, Rb) under isotropic and anisotropic pressure were investigated using first-principles calculations. The results show that the charge-ordering patterns are suppressed and there is a significant rearrangement of Van Hove point energies. The findings suggest a mechanism for tuning the correlation profile in kagome metals and provide insights for further experimental investigations on unconventional pairing and multidome superconductivity.
Article
Physics, Multidisciplinary
Yang Xu, Frantisek Herman, Veronica Granata, Daniel Destraz, Lakshmi Das, Jakub Vonka, Simon Gerber, Jonathan Spring, Marta Gibert, Andreas Schilling, Xiaofu Zhang, Shiyan Li, Rosalba Fittipaldi, Mark H. Fischer, Antonio Vecchione, Johan Chang
Summary: This study investigates the unusual Fermi liquid behavior of calcium-doped strontium ruthenate through magnetotransport, revealing the persistence of Fermi liquid properties across metamagnetic transitions and an unusually strong variation of the Kadowaki-Woods ratio. The authors suggest that this Fermi liquid behavior may stem from disorder-introduced van Hove singularities.
COMMUNICATIONS PHYSICS
(2021)
Article
Chemistry, Multidisciplinary
Donghan Kim, Younsik Kim, Byungmin Sohn, Minsoo Kim, Bongju Kim, Tae Won Noh, Changyoung Kim
Summary: By utilizing an atomically ultra-thin SrRuO3 film, the electronic structure of a 2D van Hove singularity (VHS) is investigated and controlled using angle-resolved photoemission spectroscopy and transport properties. The 2D VHS and the sign of the charge carrier are precisely controlled by applying electric fields with alkali metal deposition and ionic-liquid gating methods. This tunable 2D VHS in an atomically flat oxide film could serve as a new strategy to achieve infinite density of states (DOS) near the Fermi level, enabling efficient tuning of electric properties.
ADVANCED MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Yu-Ping Lin, Rahul M. Nandkishore
Summary: The study investigates the interaction between real and imaginary charge density waves at the Van Hove singularity on hexagonal lattices. It reveals the formation of 3Q complex orders and the rich phase diagram they constitute. The theoretical model offers transparent interpretations of experimental observations in kagome metals and sheds light on the nature of topological charge density waves.
Article
Materials Science, Multidisciplinary
Yefan Tian, Yanglin Zhu, Rui Li, Zhiqiang Mao, Joseph H. Ross
Summary: The study used nuclear magnetic resonance spectroscopy to investigate the distinctive network of nodal lines in the Dirac semimetal ZrSiTe, revealing that the low-T behavior is dominated by a symmetry-protected nodal line with quasi-two-dimensional behavior. Additionally, a Van Hove singularity closely connected to this nodal line was identified, along with an associated T-induced Lifshitz transition.
Article
Materials Science, Multidisciplinary
Anirudh Chandrasekaran, Joseph J. Betouras
Summary: This study investigates the effect of disorder on systems with energy bands in two dimensions that have higher order Van Hove singularities (HOVHS). The authors utilize standard diagrammatic techniques for impurity averaging and analyze the signatures of these singularities in disordered systems. They find that while the divergence of the density of states (DOS) is smeared, the shape of the DOS is retained slightly away from the singularity, which may help understand experiments on materials that can host HOVHS. The impurity-induced smearing is calculated and the effects on electrical conductivity are studied.
Article
Materials Science, Multidisciplinary
Omer M. Aksoy, Anirudh Chandrasekaran, Apoorv Tiwari, Titus Neupert, Claudio Chamon, Christopher Mudry
Summary: Fermi surfaces can undergo sharp transitions with topological character when higher-order singularities develop at the transition. Odd singularities appear in pairs within the Brillouin zone when time-reversal and inversion symmetries are present. The combination of enhanced density of states and nesting between the singularities leads to interaction-driven instabilities.
Article
Multidisciplinary Sciences
Junyu Zong, Zhao-Yang Dong, Junwei Huang, Kaili Wang, Qi-Wei Wang, Qinghao Meng, Qichao Tian, Xiaodong Qiu, Yuyang Mu, Li Wang, Wei Ren, Xuedong Xie, Wang Chen, Yongheng Zhang, Can Wang, Fang-Sen Li, Shao-Chun Li, Jian-Xin Li, Hongtao Yuan, Yi Zhang
Summary: In this study, the van Hove singularity (VHS) in the epitaxial monolayer (ML) 1T-VSe2 film was successfully manipulated by the giant magnified dielectric constant er of SrTiO3(111) substrate with cooling, leading to a two-dimensional (2D) itinerant ferromagnetic state below 3.3 K. The manipulation of VHS was ascribed to the physical origin of the itinerant ferromagnetic state in ML 1T-VSe2, as supported by angle-resolved photoemission spectroscopy (ARPES) and theoretical analysis. These findings demonstrate the potential of controlling the ferromagnetic state in 2D systems through VHS engineering, expanding the application possibilities of 2D magnets for next-generation information technology.
Article
Physics, Multidisciplinary
Tran C. Phong, Nguyen T. Nam, Le T. T. Phuong
Summary: By tuning the filling fractions of van Hove singularities in PbBiI quantum spin Hall insulators through two mechanisms of C3v symmetry breaking – applying an in-plane magnetization exchange field and an inversion symmetry breaking field – we can induce exotic phenomena, including the formation of Weyl nodes in the electronic band structure and the deformation of bare van Hove singularities away from the Fermi energy. The above mechanisms also lead to the increase in the number of van Hove singularities due to the reconstruction of the Fermi surface. These findings propose two efficient mechanisms for tuning/creating van Hove singularities with potential applications in optoelectronics.
Article
Materials Science, Multidisciplinary
Harrison LaBollita, Antia S. Botana
Summary: The electronic structure of the new family of kagome metals AV(3)Sb(5) can be modified by pressure and hole doping, with pressure shifting saddle points away from the Fermi level and doping bringing them closer. This demonstrates how pressure and doping can be used to tune Fermi surface instabilities and associated orders.
Article
Chemistry, Multidisciplinary
Julian Klein, Benjamin Pingault, Matthias Florian, Marie-Christin Heissenbuettel, Alexander Steinhoff, Zhigang Song, Kierstin Torres, Florian Dirnberger, Jonathan B. Curtis, Mads Weile, Aubrey Penn, Thorsten Deilmann, Rami Dana, Rezlind Bushati, Jiamin Quan, Jan Luxa, Zdenek Sofer, Andrea Alu, Vinod M. Menon, Ursula Wurstbauer, Michael Rohlfing, Prineha Narang, Marko Loncar, Frances M. Ross
Summary: In this study, it was found that the magnetic semiconductor CrSBr behaves like a quasi-1D material in a magnetically ordered environment. The strong 1D electronic character of CrSBr originates from the Cr-S chains and the weak interlayer hybridization, leading to anisotropy in effective mass and dielectric screening. Moreover, CrSBr hosts spectrally narrow excitons of high binding energy and oscillator strength due to reduced dimensionality and interlayer coupling. Overall, CrSBr is an experimentally attractive candidate for the study of exotic exciton and 1D-correlated many-body physics.
Article
Chemistry, Inorganic & Nuclear
Charlotte Pughe, Otto H. J. Mustonen, Alexandra S. Gibbs, Martin Etter, Cheng Liu, Sian E. Dutton, Aidan Friskney, Neil C. Hyatt, Gavin B. G. Stenning, Heather M. Mutch, Fiona C. Coomer, Edmund J. Cussen
Summary: Isovalent nonmagnetic d(10) and d(0) B cations can be used to tune the magnetic interactions between magnetic B' cations in perovskites. The changes in orbital hybridization and introduction of mixtures of d(10) and d(0) cations can lead to alternative magnetic structures and exotic quantum magnetism. Substituting Te6+ d(10) with W6+ d(0) in Ba2CuTeO6 affects the intraladder interactions and changes the system from a spin ladder to isolated spin chains.
INORGANIC CHEMISTRY
(2022)
Article
Chemistry, Physical
Minu Kim, Graham M. McNally, Hun-Ho Kim, Mohamed Oudah, Alexandra S. Gibbs, Pascal Manuel, Robert J. Green, Ronny Sutarto, Tomohiro Takayama, Alexander Yaresko, Ulrich Wedig, Masahiko Isobe, Reinhard K. Kremer, D. A. Bonn, Bernhard Keimer, Hidenori Takagi
Summary: Superconductivity is observed in (Ba,K)SbO3, stabilized by high-pressure synthesis, with a positive oxygen-metal charge transfer energy. This discovery suggests that strong oxygen-metal covalency might be more important than the sign of the charge transfer energy in the origin of superconductivity in main-group perovskite superconductors.
Article
Chemistry, Physical
Suguru Yoshida, Hirofumi Akamatsu, Alexandra S. Gibbs, Shogo Kawaguchi, Venkatraman Gopalan, Katsuhisa Tanaka, Koji Fujita
Summary: In this study, it is found that the competition between octahedral rotations and deformations in AgRTiO4 leads to biaxial negative thermal expansion (NTE), which is different from conventional materials. The analysis of calculated electronic structures reveals the essential role of Ag-O-Ti covalent bonding in enhancing the octahedral deformation.
CHEMISTRY OF MATERIALS
(2022)
Article
Multidisciplinary Sciences
You-Sheng Li, Markus Garst, Jorg Schmalian, Sayak Ghosh, Naoki Kikugawa, Dmitry A. Sokolov, Clifford W. Hicks, Fabian Jerzembeck, Matthias S. Ikeda, Zhenhai Hu, B. J. Ramshaw, Andreas W. Rost, Michael Nicklas, Andrew P. Mackenzie
Summary: One of the main developments in unconventional superconductivity in the past two decades is the discovery that most unconventional superconductors form phase diagrams that also contain other strongly correlated states. Tuning between the resultant ordered phases is the subject of intense research. Recently, uniaxial pressure applied using piezoelectric-based devices has been shown to be a versatile method of tuning.
Article
Multidisciplinary Sciences
Fabian Jerzembeck, Henrik S. Roising, Alexander Steppke, Helge Rosner, Dmitry A. Sokolov, Naoki Kikugawa, Thomas Scaffidi, Steven H. Simon, Andrew P. Mackenzie, Clifford W. Hicks
Summary: Applying in-plane uniaxial pressure can dramatically change the electronic structure of strongly correlated low-dimensional systems, and using pressure along the c axis can provide even stronger control over the quasi-two-dimensional structure. In the superconductor Sr2RuO4, in-plane strain enhances Tc and Hc2, but the effect of out-of-plane strain has not been studied.
NATURE COMMUNICATIONS
(2022)
Article
Multidisciplinary Sciences
Carolina A. Marques, Luke C. Rhodes, Izidor Benedicic, Masahiro Naritsuka, Aaron B. Naden, Zhiwei Li, Alexander C. Komarek, Andrew P. Mackenzie, Peter Wahl
Summary: The phenomenon and radical changes observed in material properties during a quantum phase transition have attracted significant attention in condensed matter research in recent decades. Strong electronic correlations give rise to exotic electronic ground states, such as magnetic order, nematicity, and unconventional superconductivity. A detailed understanding of the electronic structure near the Fermi energy is necessary to provide a microscopic model for these phenomena and achieve a complete understanding of the physics of the quantum critical point.
Article
Materials Science, Multidisciplinary
Celesta S. Chang, Jiaxin Sun, Seunghyun Khim, Andrew P. Mackenzie, Darrell G. Schlom, David A. Muller
Summary: By studying single crystals and epitaxial thin films, we have found that ribbonlike defects are dominant in single-crystal PdCoO2, while different types of defects arising from substrate termination disrupt the lateral connectivity of the conducting planes in thin films. To enhance the quality of PdCoO2 films, selecting a proper substrate, improving surface quality, and reducing the step density are key factors.
PHYSICAL REVIEW MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
Moritz M. Hirschmann, Alexandra S. Gibbs, Fabio Orlandi, Dmitry Khalyavin, Pascal Manuel, Vahideh Abdolazimi, Alexander Yaresko, Juergen Nuss, H. Takagi, Andreas P. Schnyder, Andreas W. Rost
Summary: This study establishes Eu3PbO as a new topological magnetic semimetal with multiple topological phases that can be controlled by an external magnetic field.
PHYSICAL REVIEW MATERIALS
(2022)
Article
Chemistry, Physical
Charlotte Pughe, Otto H. J. Mustonen, Alexandra S. Gibbs, Stephen Lee, Rhea Stewart, Ben Gade, Chennan Wang, Hubertus Luetkens, Anna Foster, Fiona C. Coomer, Hidenori Takagi, Edmund J. Cussen
Summary: Ba2CuTeO6 is a material with a two-leg spin ladder structure of Cu2+ cations, which can be chemically tuned by substituting non-magnetic Zn2+ at the Cu2+ site. The substitution partitions the spin ladders into clusters, leading to a transition from long-range order to spin-freezing as the Zn2+ substitution increases. This provides a well-controlled tuning of the magnetic disorder and a model system for studying defects and segmentation in low-dimensional quantum magnets.
CHEMISTRY OF MATERIALS
(2023)
Article
Physics, Multidisciplinary
Belen E. Zuniga-Cespedes, Kaustuv Manna, Hilary M. L. Noad, Po-Ya Yang, Michael Nicklas, Claudia Felser, Andrew P. Mackenzie, Clifford W. Hicks
Summary: By applying a combination of uniaxial stress and magnetic field, we have observed a significant anomalous Hall effect in a bulk sample of a cubic member of the Mn3X family for the first time. The observed effect remains unchanged when the stress is removed, indicating that it is not induced by stress-induced ferromagnetic moments.
NEW JOURNAL OF PHYSICS
(2023)
Article
Physics, Multidisciplinary
Edgar Abarca Morales, Gesa-R. Siemann, Andela Zivanovic, Philip A. E. Murgatroyd, Igor Markovic, Brendan Edwards, Chris A. Hooley, Dmitry A. Sokolov, Naoki Kikugawa, Cephise Cacho, Matthew D. Watson, Timur K. Kim, Clifford W. Hicks, Andrew P. Mackenzie, Phil D. C. King
Summary: We present the evolution of the electronic structure at the surface of Sr2RuO4 under large in-plane uniaxial compression, resulting in anisotropic B1g strains. Using angle-resolved photoemission, we observe a sequence of Lifshitz transitions that reshape the electronic structure and van Hove singularities on the surface. Our study reveals the nature of structural distortions at oxide surfaces and the possibility of controlling the density of state singularities for the realization of collective states at the Sr2RuO4 surface.
PHYSICAL REVIEW LETTERS
(2023)
Article
Instruments & Instrumentation
F. Sun, S. Mishra, P. H. McGuinness, Z. H. Filipiak, I. Markovic, D. A. Sokolov, N. Kikugawa, J. W. Orenstein, S. A. Hartnoll, A. P. Mackenzie, V. Sunko
Summary: We propose an optical method for directly measuring the position-dependent thermal diffusivity of reflective single crystal samples in condensed matter physics research. By using two laser beams, one to modulate the sample temperature and the other to probe sample reflectivity, we obtain the thermal diffusivity by analyzing the phase delay between the two signals. This technique can provide spatially resolved measurements and enhanced spatial resolution to a micron scale. We demonstrated the effectiveness of this method on two stoichiometric bilayer ruthenates and Ti-doped Ca3Ru2O7, revealing temperature-dependent diffusivity and inhomogeneity.
REVIEW OF SCIENTIFIC INSTRUMENTS
(2023)
Article
Multidisciplinary Sciences
P. J. Curran, S. J. Bending, A. S. Gibbs, A. P. Mackenzie
Summary: Scanning Hall microscopy was used to search for spontaneous edge fields in mesa structures of Sr2RuO4 single crystals, but no evidence was found. However, pronounced vortex clustering was observed at low temperatures and fields, in line with the semi-Meissner scenario due to the multiband nature of superconductivity. Clear evidence of a square vortex lattice inside square mesa structures above 1.3K was also seen. The results are discussed in relation to recent experimental findings and theoretical predictions.
SCIENTIFIC REPORTS
(2023)
Article
Materials Science, Multidisciplinary
Elina Zhakina, Philippa H. McGuinness, Markus Koenig, Romain Grasset, Maja D. Bachmann, Seunghyun Khim, Carsten Putzke, Philip J. W. Moll, Marcin Konczykowski, Andrew P. Mackenzie
Summary: High-energy electron irradiation is used to study the effects on PtCoO2, and it is found that this technique can transition from nonlocal to local transport behavior, thus determining the nature and extent of unconventional transport regimes.
Article
Materials Science, Multidisciplinary
Fabian Jerzembeck, Alexander Steppke, Andrej Pustogow, Yongkang Luo, Aaron Chronister, Dmitry A. Sokolov, Naoki Kikugawa, You-Sheng Li, Michael Nicklas, Stuart E. Brown, Andrew P. Mackenzie, Clifford W. Hicks
Summary: In-plane uniaxial pressure can strongly tune the superconducting state of Sr2RuO4 by approaching a Lifshitz transition and associated Van Hove singularity (VHS) in the density of states. The in-plane upper critical field is mostly linear in Tc, while the out-of-plane upper critical field varies with a higher power in Tc and peaks strongly at the VHS. The change in magnitude and form of Hc2||c occur very close to the Van Hove strain, pointing to a strong enhancement of both the density of states and the gap magnitude at the Lifshitz transition.
