Article
Multidisciplinary Sciences
Kai Yang, Soo-Hyon Phark, Yujeong Bae, Taner Esat, Philip Willke, Arzhang Ardavan, Andreas J. Heinrich, Christopher P. Lutz
Summary: Designing and characterizing many-body behaviors of quantum materials is crucial for understanding strongly correlated physics and quantum information processing. By constructing artificial quantum magnets with spin-1/2 atoms in a scanning tunneling microscope, researchers are able to study exotic quantum many-body states like the resonating valence bond state at an atomic scale. This approach offers a new avenue for designing and exploring quantum magnets for spintronics and quantum simulations.
NATURE COMMUNICATIONS
(2021)
Article
Physics, Multidisciplinary
Yi-Fan Jiang, Hong Yao, Fan Yang
Summary: In this Letter, a new class of variational states for the doped t-J model on the Kagome lattice is proposed and investigated through large-scale variational Monte Carlo simulation. The resulting chiral noncentrosymmetric nematic superconducting state is found to possess a finite Fermi surface for Bogoliubov quasiparticles. The experimental properties of this intriguing pairing state are further studied.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Multidisciplinary
Quentin Barthelemy, Albin Demuer, Christophe Marcenat, Thierry Klein, Bernard Bernu, Laura Messio, Matias Velazquez, Edwin Kermarrec, Fabrice Bert, Philippe Mendels
Summary: Measuring the specific heat of herbertsmithite single crystals in high magnetic fields allows us to isolate and understand the low-temperature kagome contribution. The kagome contribution is found to be independent of the applied magnetic field within a specific temperature range, and this behavior can be reproduced by considering non-contributing sites. Additionally, anomalies in the total specific heat at very low temperatures and moderate fields are observed and further investigated.
Article
Materials Science, Multidisciplinary
Zhen Wang, Hengcan Zhao, Meng Lyu, Junsen Xiang, Yosikazu Isikawa, Shuai Zhang, Peijie Sun
Summary: We report on the long-range antiferromagnetic ordering and heavy-fermion-like behaviors in PrPdAl, which is a Kondo lattice with kagome-like structure. The results demonstrate the competing ground states in frustrated Kondo lattices formed by non-Kramers magnetic ions.
Article
Physics, Multidisciplinary
Hong-Chen Jiang, Steven A. Kivelson
Summary: In a t-J model with small hole doping and frustration, power-law superconducting correlations and exponentially decreasing spin-spin correlations were observed, suggesting a smooth evolution from the insulating parent state. The presence of frustration led to a strong diverging superconducting susceptibility as the temperature approached zero.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Multidisciplinary
M. E. Zhitomirsky, M. V. Gvozdikova, T. Ziman
Summary: We investigate the classical ground states of frustrated Heisenberg models on pyrochlore and kagome lattices in zero and finite magnetic fields analytically and numerically. We find noncoplanar triple -k spin configurations in a wide region of the parameter space for both models, and transitions from 3-k to 2-k states induced by strong magnetic fields. These transitions may explain the observed phase transitions in cubic spinels GeNi2O4 and GeCo2O4.
Article
Physics, Condensed Matter
Kingshuk Majumdar, Subhendra D. Mahanti
Summary: A novel two-dimensional frustrated quantum spin-1/2 anisotropic Heisenberg model is proposed, showing properties of ferrimagnetism in certain interaction space and a quantum phase transition with characteristics of both frustrated 2D antiferromagnetic S = 1/2 and 1D quantum ferrimagnetic models.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2021)
Article
Multidisciplinary Sciences
Eun Kyo Ko, Sungsoo Hahn, Changhee Sohn, Sangmin Lee, Seung-Sup B. Lee, Byungmin Sohn, Jeong Rae Kim, Jaeseok Son, Jeongkeun Song, Youngdo Kim, Donghan Kim, Miyoung Kim, Choong H. Kim, Changyoung Kim, Tae Won Noh
Summary: Hund's coupling, or the intra-atomic exchange, can drive novel quantum phases in multi-orbital systems, but this requires precise control of orbital occupancy. Ko et al. report an orbital-selective metal-to-insulator transition driven by Hund's physics via symmetry-preserving strain tuning in monolayer SrRuO3.
NATURE COMMUNICATIONS
(2023)
Article
Materials Science, Multidisciplinary
Cheng Peng, Yi-Fan Jiang, Thomas P. Devereaux, Hong-Chen Jiang
Summary: The study focuses on the effects of doping the Kitaev model on the honeycomb lattice, revealing that under light doping, the ground state of the system exhibits dominant quasi-long-range charge-density-wave correlations. In the pairing channel, even-parity superconducting correlation with d-wave-like symmetry is predominant, oscillating in sign with a period equal to that of the spin-density wave and two times the charge-density wave.
NPJ QUANTUM MATERIALS
(2021)
Article
Materials Science, Multidisciplinary
Shankar Balasubramanian, Victor Galitski, Ashvin Vishwanath
Summary: We study easy-axis spin models and their low-energy descriptions on lattices, and construct other families of Hamiltonians based on wavefunction dualities.
Article
Physics, Condensed Matter
Boqiang Li, Zongtang Wan, Yiru Song, Zhaohua Ma, Yuqian Zhao, Junfeng Wang, Yuesheng Li
Summary: We propose β-BaNi3(VO4)(2)(OH)(2) as a candidate for the spin-1 kagome Heisenberg antiferromagnet. Experimental measurements at low temperatures reveal properties similar to the pure S = 1 kagome Heisenberg antiferromagnetic model.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2023)
Article
Materials Science, Multidisciplinary
K. B. Yogendra, Tanmoy Das, G. Baskaran
Summary: In this study, the Kitaev model on a one-dimensional ladder setting was investigated using the density-matrix renormalization group method in the presence of a magnetic field at zero temperature. Five distinct phases were observed with increasing magnetic field, and the emergence of glassy behavior was confirmed.
Review
Physics, Multidisciplinary
J. Khatua, B. Sana, A. Zorko, M. Gomilsek, K. Sethupathi, M. S. Ramachandra Rao, M. Baenitz, B. Schmidt, P. Khuntia
Summary: This review discusses a variety of novel quantum and topological states that can arise from frustration in magnetic materials. These include magnetically-disordered spin ices, highly-entangled quantum spin liquids, topological magnetism, and complex particle-like topological spin textures. The review provides an overview of recent advances in the search for magnetically-disordered candidate materials and emphasizes the experimental techniques for detecting these elusive phenomena. It aims to serve as a comprehensive guide for designing and investigating frustrated magnetic materials.
PHYSICS REPORTS-REVIEW SECTION OF PHYSICS LETTERS
(2023)
Article
Chemistry, Physical
Muqing Hua, Bowen Xia, Miao Wang, En Li, Jing Liu, Tianhao Wu, Yifan Wang, Ruoning Li, Honghe Ding, Jun Hu, Yongfeng Wang, Junfa Zhu, Hu Xu, Wei Zhao, Nian Lin
Summary: The study demonstrates the design and synthesis of a single-layer two-dimensional metal-organic framework containing a Kagome lattice of Fe(II) ions on a gold surface, with Fe(II) ions shown to be in a high spin state and exhibiting various degenerated spin configurations. Remarkably, a spin excitation at 6 meV was observed, pointing towards a possible route to realize a spin 1/2 Kagome antiferromagnetic system by replacing Fe(II) with Cu(II) in the same structure.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2021)
Article
Physics, Multidisciplinary
Yixuan Huang, Shou-Shu Gong, D. N. Sheng
Summary: In this Letter, the mechanism to realize topological superconductivity (TSC) in doped Mott insulators with time-reversal symmetry (TRS) is explored. A d+id-wave chiral TSC with spontaneous TRS breaking is identified, characterized by a Chern number C=2 and quasi-long-range superconducting order. The quantum phase diagram is mapped out by tuning the next-nearest-neighbor (NNN) electron hopping and spin interaction. A pseudogaplike phase coexisting with fluctuating superconductivity is found in the weaker NNN-coupling regime, which can be tuned into d-wave superconductivity by increasing the doping level and system width. The emergence of TSC in the intermediate-coupling regime is driven by geometrical frustrations and hole dynamics that suppress spin correlation and charge order, leading to a topological quantum phase transition.
PHYSICAL REVIEW LETTERS
(2023)
Article
Materials Science, Multidisciplinary
Rajyavardhan Ray, Banasree Sadhukhan, Manuel Richter, Jorge I. Facio, Jeroen van den Brink
Summary: Even if Weyl semimetals are characterized by quasiparticles with well-defined chirality, the experimental exploitation of this feature is severely limited by pairs of Weyl lattice fermions with opposite chirality, causing the net chirality to vanish. However, this issue can be overcome when both time-reversal and inversion symmetry are broken. By investigating chirality in the carbide family RMC2, we found several members to be Weyl semimetals and demonstrated in NdRhC2, a noncentrosymmetric ferromagnet, that an odd number of Weyl nodes can be stabilized at its Fermi surface by tilting its magnetization. The resulting chiral configuration leads to topological phase transitions and interesting chiral electromagnetic responses, and the tilt direction determines the sign and strength of the net chirality.
NPJ QUANTUM MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
Yaqian Guo, Hui Liu, Oleg Janson, Ion Cosma Fulga, Jeroen van den Brink, Jorge I. Facio
Summary: It has been discovered that collinear antiferromagnets, depending on their symmetries, can break the spin degeneracy in momentum space without spin-orbit coupling. These systems, known as altermagnets, are characterized by a spin-momentum texture determined by crystal and magnetic structure. This study focuses on q = 0 antiferromagnetic compounds in the MAGNDATA database and introduces numerical measures for average momentum-space spin splitting, analyzing over sixty compounds including CoF2, FeSO4F, LiFe2F6, RuO2, CrNb4S8, and CrSb.
MATERIALS TODAY PHYSICS
(2023)
Article
Multidisciplinary Sciences
Hiroki Ueda, Mirian Garcia-Fernandez, Stefano Agrestini, Carl P. Romao, Jeroen van den Brink, Nicola A. Spaldin, Ke-Jin Zhou, Urs Staub
Summary: The concept of chirality plays a crucial role in various natural phenomena. Recent studies in condensed matter physics have revealed the existence of chiral fermions and their connection to emergent phenomena and topology. However, experimental verification of chiral phonons in macroscopic systems remains challenging. In this study, we provide experimental evidence of chiral phonons using resonant inelastic X-ray scattering with circularly polarized X-rays. By studying the chiral material quartz, we demonstrate that circularly polarized X-rays couple to chiral phonons at specific positions in reciprocal space, allowing for the determination of the chiral dispersion of lattice modes. This experimental proof of chiral phonons introduces a new degree of freedom in condensed matter physics, with both fundamental importance and potential for exploring novel emergent phenomena based on chiral bosons.
Article
Materials Science, Multidisciplinary
Dennis Wawrzik, Jorge I. Facio, Jeroen van den Brink
Summary: In recent years, the concept of electronic Berry curvature (BC) has been recognized as crucial for understanding and predicting physical properties of crystalline materials. While non-magnetic materials with inversion symmetry have a strictly zero BC in their bulk, we demonstrate that a finite BC can emerge at their surfaces and interfaces, resulting in Hall-type transport responses. Through first principles calculations, we observe the presence of a surface Berry curvature dipole and associated quantum nonlinear Hall effects at various symmetries of bismuth, mercury-telluride (HgTe), and rhodium surfaces. This discovery opens up a wide range of materials to explore and harness the physical effects arising from electronic Berry curvature exclusively at their boundaries.
MATERIALS TODAY PHYSICS
(2023)
Article
Physics, Applied
Rakshanda Dhawan, Vikrant Chaudhary, Chandan Kumar Vishwakarma, Mohd Zeeshan, Tashi Nautiyal, Jeroen van den Brink, Hem C. Kandpal
Summary: Anomalous carrier transport in magnetic Heusler compounds has attracted significant attention due to their unique band structure and broken time-reversal symmetry. In this study, we investigate the properties of CoFeSn and propose a cubic polymorph based on structural stability, lattice dynamics, and magnetic analysis. Utilizing density-functional-theory calculations, we predict that cubic CoFeSn exhibits robust half-metallic ferromagnetic behavior with a high Curie temperature and significant spin Hall conductivity. We also find that adjusting the Fermi level can enhance the anomalous Hall conductivity or spin Hall conductivity. Our findings provide important insights for the realization of quantum anomalous and spin Hall effects in half-Heusler compounds.
APPLIED PHYSICS LETTERS
(2023)
Article
Multidisciplinary Sciences
Wuyang Ren, Wenhua Xue, Shuping Guo, Ran He, Liangzi Deng, Shaowei Song, Andrei Sotnikov, Kornelius Nielsch, Jeroen van den Brink, Guanhui Gao, Shuo Chen, Yimo Han, Jiang Wu, Ching-Wu Chu, Zhiming Wang, Yumei Wang, Zhifeng Ren
Summary: Studies have shown that vacancy-mediated anomalous transport properties are flourishing in various fields due to their fascinating effects on photoelectric, ferroelectric, and spin-electric behaviors in solid materials. In this study, the authors reveal the multifunctionality of vacancy in tailoring the transport properties of a defective half-Heusler ZrNiBi material, providing insights into the phononic and electronic transport processes. These findings not only demonstrate the potential of this thermoelectric material but also promote further exploration of vacancy-mediated transport properties.
NATURE COMMUNICATIONS
(2023)
Article
Physics, Multidisciplinary
Carmine Ortix, Jeroen van den Brink
Summary: Magnetoelectric crystals have the ability to convert electric fields into magnetic polarizations and magnetic fields into ferroelectric polarizations. In this study, a new method is proposed to achieve linear magnetoelectric coupling in ferromagnetic insulators using nanoscale curved geometries and intrinsic Dzyaloshinskii-Moriya interaction (DMI). The reorganization of the magnetic texture induced by the combination of curved geometries and DMI breaks inversion symmetry and creates macroscopic magnetoelectric multipoles. This study demonstrates the activation of a magnetoelectric monopole in two-dimensional magnets through controlled ripples and the direct linear magnetoelectric coupling in zigzag-shaped ferromagnetic wires.
PHYSICAL REVIEW RESEARCH
(2023)
Article
Materials Science, Multidisciplinary
Viktor Koenye, Lotte Mertens, Corentin Morice, Dmitry Chernyavsky, Ali G. Moghaddam, Jasper van Wezel, Jeroen van den Brink
Summary: We demonstrate that tilted Weyl semimetals with spatially varying tilt can be used to study anisotropic optics and curved spacetime. By examining specific tilting configurations, we numerically analyze the time evolution of electronic wave packets and current densities. Our results show that electron trajectories in such systems can be determined using Fermat's principle with an inhomogeneous, anisotropic effective refractive index. Additionally, we show that these systems can simulate gravitational lensing around a synthetic black hole, revealing gravitational features.
Article
Physics, Multidisciplinary
Ayushi Singhania, Jeroen van den Brink, Satoshi Nishimoto
Summary: This study investigates the interplay of disorder and Heisenberg interactions in the Kitaev model on a honeycomb lattice. The effects of disorder on the transition between Kitaev spin liquid and magnetic ordered states as well as the stability of magnetic ordering are examined. The results show that disorder reduces the range of spin-liquid phases and changes the transitions to magnetic ordered phases to a more crossoverlike behavior. In addition, long-range orderings in the clean system are replaced by domains with different ordering directions.
PHYSICAL REVIEW RESEARCH
(2023)
Article
Materials Science, Multidisciplinary
Shruti Agarwal, Shreekant Gawande, Satoshi Nishimoto, Jeroen Van den Brink, Sanjeev Kumar
Summary: Using a combination of mean-field Bogoliubov-de Gennes approach and density matrix renormalization group method, we discovered first-order topological transitions between topological superconducting and trivial insulating phases in a sawtooth lattice of intersite attractive fermions. The topological properties of different phases were characterized in terms of winding numbers, Majorana edge modes, and entanglement spectra. By studying the effect of disorder on first-order topological phase transitions, we established disorder-induced topological phase coexistence as a mechanism for generating a finite density of Majorana particles.
Article
Physics, Multidisciplinary
Viktor Koenye, Corentin Morice, Dmitry Chernyavsky, Ali G. Moghaddam, Jeroen van den Brink, Jasper van Wezel
Summary: In this study, we simulate the dynamics of massless Dirac fermions in curved space-times with one, two, and three spatial dimensions by constructing tight-binding Hamiltonians with spatially varying hoppings. These models represent tilted Weyl semimetals where the tilting varies with position, similar to the light cones near the horizon of a black hole. We demonstrate the gravitational analogies in these models by numerically evaluating the propagation of wave packets on the lattice and comparing them to the geodesics of the corresponding curved space-time. We also show that the motion of electrons in these spatially varying systems can be understood through the conservation of energy and the quasiconservation of quasimomentum. Furthermore, we reveal that horizons in the lattice models can be constructed with finite energies using specially designed tilting profiles.
PHYSICAL REVIEW RESEARCH
(2022)
Article
Physics, Multidisciplinary
Gabriele Naselli, Ali G. Moghaddam, Solange Di Napoli, Veronica Vildosola, Ion Cosma Fulga, Jeroen van den Brink, Jorge I. Facio
Summary: We analyze the electronic structure of topological surface states in the family of magnetic topological insulators. We show that, at the magnetic ordering temperature, the symmetry of the Dirac cone warping changes from hexagonal to trigonal, leading to energy splitting between surface states. This energy splitting can be used as a simple protocol to detect magnetic ordering via the surface electronic structure.
PHYSICAL REVIEW RESEARCH
(2022)
Article
Materials Science, Multidisciplinary
Thomas Halloran, Yishu Wang, Mengqun Li, Ioannis Rousochatzakis, Prashant Chauhan, M. B. Stone, Tomohiro Takayama, Hidenori Takagi, N. P. Armitage, Natalia B. Perkins, Collin Broholm
Summary: This study presents a comprehensive experimental investigation of the three-dimensional hyperhoneycomb Kitaev magnet beta-Li2IrO3 using various techniques. The main findings include the reorganization of the INS spectral weight and the presence of a distinctive peak in the terahertz data. Comparison with spin-wave theory calculations reveals the control of the positions of these features by the anisotropic Gamma coupling and the Heisenberg exchange J, respectively. The refined spin model suggests that beta-Li2IrO3 is close to the Kitaev spin liquid phase.
Article
Materials Science, Multidisciplinary
Yang Yang, Yiping Wang, Ioannis Rousochatzakis, Alejandro Ruiz, James G. Analytis, Kenneth S. Burch, Natalia B. Perkins
Summary: We investigated the magnetic excitations of the hyperhoneycomb Kitaev magnet ??-Li2IrO3 using inelastic Raman scattering. The spectra showed the coexistence of a broad scattering continuum and two sharp low-energy peaks, with polarization dependence. The continuum suggests the presence of fractional quasiparticles from a nearby quantum spin liquid phase, while the sharp peaks provide experimental evidence of the proposed non-Loudon-Fleury one-magnon scattering processes. This calls for a reevaluation of Raman scattering in similar systems with strong spin-orbit coupling and multiple exchange paths.
Article
Materials Science, Multidisciplinary
Shiang Fang, Linda Ye, Madhav Prasad Ghimire, Mingu Kang, Junwei Liu, Minyong Han, Liang Fu, Manuel Richter, Jeroen van den Brink, Efthimios Kaxiras, Riccardo Comin, Joseph G. Checkelsky
Summary: In this study, we investigated the electronic structure of the ferromagnetic kagome metal Fe3Sn2 without spin-orbit coupling. We found two energetically split helical nodal lines near K and K' in the Brillouin zone, resulting from the trigonal stacking of the kagome layers. The hopping across A-A stacking introduced energy splitting, while that across A-B stacking controlled the momentum space amplitude of the helical nodal lines. Our findings have important implications for the design of topological materials.