Article
Materials Science, Multidisciplinary
A. Niyazi, D. Geffroy, J. Kunes
Summary: In this study, we explored the dynamical mean-field properties of antiferromagnetic magnons in a one-, two-, and three-orbital Hubbard model under intermediate coupling strength. The effects of anisotropy introduced by external magnetic field or single-ion anisotropy were investigated, with a continuous tuning between easy-axis and easy-plane models. It was found that ordered states and magnetic excitations are sensitive to even small breaking of SU(2) symmetry of the model, in line with spin-wave theory and general symmetry considerations.
Article
Physics, Multidisciplinary
Xinyang Dong, Emanuel Gull, Andrew J. Millis
Summary: This study investigates the contribution of electron-spin-fluctuation coupling to the superconducting state in a two-dimensional Hubbard model using the dynamical cluster approximation. The findings suggest that only about half of the superconductivity can be attributed to the pairing mechanism involving spin fluctuations as pairing bosons in the standard one-loop theory.
Article
Materials Science, Multidisciplinary
E. K. Petrov, V. N. Men'shov, I. P. Rusinov, M. Hoffmann, A. Ernst, M. M. Otrokov, V. K. Dugaev, T. Menshchikova, E. Chulkov
Summary: This paper suggests a method to realize topologically protected spin-polarized flat bands generated by domain walls in planar magnetic topological insulators, demonstrating their existence near the Fermi level and discussing their potential applications in intrinsic antiferromagnetic topological insulators.
Article
Physics, Multidisciplinary
Annabelle Bohrdt, Lukas Homeier, Immanuel Bloch, Eugene Demler, Fabian Grusdt
Summary: Studies suggest that high-temperature pairing of fermions can be achieved in bilayer models, utilizing the energy gained by one charge when it follows the path created by another charge.
Article
Materials Science, Multidisciplinary
Johann Ostmeyer, Evan Berkowitz, Stefan Krieg, Timo A. Laehde, Thomas Luu, Carsten Urbach
Summary: In this study, a comprehensive analysis of the operators contributing to the structure factors and order parameters of the hexagonal Hubbard Model was conducted using the Hybrid Monte Carlo algorithm. The results improve the consistency of Monte Carlo determinations of critical exponents and provide insights into the semimetal-Mott insulator transition in the hexagonal Hubbard Model. The methods employed are applicable to a wide range of lattice theories involving strongly correlated electrons.
Article
Materials Science, Multidisciplinary
Florian Johannesmann, Jannis Eckseler, Henrik Schlueter, Juergen Schnack
Summary: We investigate the one-magnon dynamics of the antiferromagnetic delta chain, which serves as a paradigmatic example of tunable equilibration. Depending on the ratio of nearest and next-nearest exchange interactions, the spin system exhibits either a flat band or dispersive bands, and we provide analytical and numerical insight into this phenomenon.
Article
Physics, Multidisciplinary
Frank Goehmann, Karol K. Kozlowski, Jesko Sirker, Junji Suzuki
Summary: In this study, we present a series representation for the dynamical two-point function of the local spin current for the XXZ chain in the antiferromagnetic massive regime at zero temperature. We can compute the correlation function with high accuracy and interpret the terms in the series as contributions from scattering states of excitations in terms of particles and holes.
Article
Physics, Multidisciplinary
Roman Rausch, Cassian Plorin, Matthias Peschke
Summary: In this study, the quantum-mechanical antiferromagnetic Heisenberg model of spins on a truncated icosahedron is solved using the density-matrix renormalization group (DMRG). The research focuses on the magnetic properties of the undoped C-60 fullerene at half filling under strong on-site interaction U. It is found that frustration can be tuned within fullerenes by changing their size, and the spin-spin correlations are stronger along hexagon bonds, decreasing exponentially with distance.
Article
Multidisciplinary Sciences
G. Sala, M. B. Stone, Binod K. Rai, A. F. May, Pontus Laurell, V. O. Garlea, N. P. Butch, M. D. Lumsden, G. Ehlers, G. Pokharel, A. Podlesnyak, D. Mandrus, D. S. Parker, S. Okamoto, Gabor B. Halasz, A. D. Christianson
Summary: Researchers utilized inelastic neutron scattering to investigate the spin correlations of the honeycomb lattice quantum magnet YbCl3, identifying key features such as the Van Hove singularity. The results confirm widely held notions about quantum magnetism continua and establish YbCl3 as a benchmark material for quantum magnetism on the honeycomb lattice.
NATURE COMMUNICATIONS
(2021)
Article
Materials Science, Multidisciplinary
Jan Lukas Bosse, Ashley Montanaro
Summary: In this study, the variational quantum eigensolver (VQE) is proposed to find the ground state of the antiferromagnetic Heisenberg model on the kagome lattice (KAFH) on a quantum computer. The expressiveness and scaling of the ansatz circuits are investigated through classical simulations. The results show that, except for a specific lattice configuration, the fidelity with the ground state approaches one exponentially with the circuit depth, indicating the potential achievability of representing the ground state of KAFH on inaccessible lattices using VQE circuits on near-term quantum hardware.
Article
Physics, Multidisciplinary
Rahul Soni, Nitin Kaushal, Cengiz Sen, Fernando A. Reboredo, Adriana Moreo, Elbio Dagotto
Summary: In this study, a multi-orbital Hubbard model with two and three orbitals per site was studied using full exact diagonalization. The results were mapped into Heisenberg models at intermediate and large onsite repulsion U. The study provides an estimate for the ratios J(2)/J(1) and J(3)/J(1) in these effective models, showing that they are rather limited and can be enhanced in the intermediate Hubbard U regime.
NEW JOURNAL OF PHYSICS
(2022)
Article
Chemistry, Inorganic & Nuclear
Alisher F. Murtazoev, Peter S. Berdonosov, Konstantin A. Lyssenko, Valery A. Dolgikh, Zlata V. Pchelkina, Konstantin V. Zakharov, Michael Y. Geidorf, Tatyana M. Vasilchikova, Olga S. Volkova, Alexander N. Vasiliev
Summary: Anhydrous copper tellurite sulfate, Cu3TeO3(SO4)(2), was synthesized via vapor transport reactions in sealed silica glass ampoules. Various measurements revealed long-range antiferromagnetic order at T-N = 13 K and established an H-T magnetic phase diagram. Density functional theory calculations provided estimations of leading exchange interaction parameters.
DALTON TRANSACTIONS
(2023)
Article
Materials Science, Multidisciplinary
Tomonari Mizoguchi, Yoshihito Kuno, Yasuhiro Hatsugai
Summary: The study reveals characteristic band structures of fermions on a square kagome lattice, including flat bands and two spin-1 Dirac cones. Additionally, in the presence of an external field, the profile of the Chern numbers around the modified spin-1 Dirac cones coincides with the conventional one.
Article
Materials Science, Multidisciplinary
Sauri Bhattacharyya, Pinaki Majumdar
Summary: This study investigates the equilibrium dynamics of magnetic moments in the Mott insulating phase of the Hubbard model on square and triangular lattices. By rewriting the Hubbard interaction in terms of an auxiliary vector field and incorporating thermal noise derived from the Keldysh formalism, the research explores the impact of finite temperature. The findings reveal deviations from Heisenberg physics with decreasing U/t, exemplified by changes in low-temperature dispersion and crossover temperatures related to enhanced mode coupling at weaker U/t. Additionally, comparisons between square and triangular lattices demonstrate the added effect of geometric frustration on damping.
Article
Materials Science, Multidisciplinary
Qi Wei, Jianxiong Zhai, Zhijun Ning, Youqi Ke
Summary: We present a generalized auxiliary coherent medium theory to address the long-standing challenge of simulating Anderson-type off-diagonal disorder (AODD) in disordered alloys. By transforming AODD into a diagonal-like disorder with a weighted discrete distribution in an auxiliary medium, we show that our approach substantially improves the accuracy of simulating the phonon linewidth in NiFe and NiPt alloys, compared to results obtained with averaged-value off-diagonal disorder (ODD). This paper provides an effective approach for dealing with large fluctuations in ODD in disordered materials, representing an important progress for mean-field simulations in the embedding framework.
Article
Chemistry, Multidisciplinary
Ziqian Wang, Meng Gao, Tonghua Yu, Siyuan Zhou, Mingquan Xu, Motoaki Hirayama, Ryotaro Arita, Yuki Shiomi, Wu Zhou, Naoki Ogawa
Summary: Stacking order plays a significant role in the properties of van der Waals layered magnets, and recent studies suggest possible different stackings in few-layer crystals. This study combines atomic-scale electron microscopy and theoretical calculations to show that while the bulk stacking persists in bilayers of MnPS3, the local rippling effect lifts the monoclinic symmetry of the few layers. This finding reveals the impact of rippling on the microscopic symmetry of two-dimensional materials and suggests the possibility of approaching the two-dimensional Neel antiferromagnetic honeycomb lattice in MnPS3 without reaching monolayer thickness.
Article
Multidisciplinary Sciences
Xianzhe Chen, Tomoya Higo, Katsuhiro Tanaka, Takuya Nomoto, Hanshen Tsai, Hiroshi Idzuchi, Masanobu Shiga, Shoya Sakamoto, Ryoya Ando, Hidetoshi Kosaki, Takumi Matsuo, Daisuke Nishio-Hamane, Ryotaro Arita, Shinji Miwa, Satoru Nakatsuji
Summary: The tunnelling magnetoresistance (TMR) in magnetic tunnel junctions (MTJs) is usually studied in ferromagnetic materials, but this study reports the observation of TMR in an all-antiferromagnetic tunnel junction. A TMR ratio of about 2% was measured at room temperature, which is attributed to the configuration of cluster magnetic octupoles in the chiral antiferromagnetic state. Sign and direction of anisotropic longitudinal spin-polarized current in the antiferromagnet can be controlled by octupole direction. Theoretical analysis suggests that the chiral antiferromagnetic MTJ can produce a substantially large TMR ratio due to the time-reversal, symmetry-breaking polarization characteristic of cluster magnetic octupoles.
Article
Physics, Applied
Takuya Nomoto, Ryotaro Arita
Summary: In recent years, the skyrmion lattice phase with a short lattice constant has been studied for its high skyrmion density and potential applications in high-density storage memory and the observation of novel phenomena like the quantized topological Hall effect. This Perspective focuses on the first-principles evaluations of the formation mechanism and potential skyrmion materials, with a specific focus on the prototype systems GdT2X2 and EuT2X2. The results show that the Hubbard U and Hund's coupling play crucial roles in stabilizing a skyrmion lattice state and that certain materials, such as GdRu2X2 and GdOs2X2, show promise as skyrmion host materials.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Physics, Multidisciplinary
H. Takagi, R. Takagi, S. Minami, T. Nomoto, K. Ohishi, M. -t. Suzuki, Y. Yanagi, M. Hirayama, N. D. Khanh, K. Karube, H. Saito, D. Hashizume, R. Kiyanagi, Y. Tokura, R. Arita, T. Nakajima, S. Seki
Summary: The spontaneous topological Hall effect in triangular lattice compounds CoTa3S6 and CoNb3S6 is experimentally demonstrated, combining non-coplanar antiferromagnetic order with finite scalar spin chirality in the absence of a magnetic field. These compounds exhibit unconventionally large spontaneous Hall effects despite their small net magnetization, and the mechanism behind this phenomena is explained by the topological Hall effect associated with scalar spin chirality. The results suggest that the scalar spin chirality mechanism offers a promising route for the realization of a giant spontaneous Hall response in compensated antiferromagnets.
Article
Nanoscience & Nanotechnology
Motoharu Kitatani, Yusuke Nomura, Motoaki Hirayama, Ryotaro Arita
Summary: Motivated by recent theoretical materials design, we calculate the phase diagram of RbCa2NiO3 and A(2)NiO(2)Br(2) using the dynamical vertex approximation. We find that these nickelates exhibit similar phase features as cuprates, where superconductivity emerges from hole-doped antiferromagnetic Mott insulators with a dome-like superconducting transition temperature. This highlights the crucial role of electron correlations in nickelate superconductors, which can be controlled by modifying the block layers.
Article
Chemistry, Multidisciplinary
Taishi Noma, Hsiao-Yi Chen, Barun Dhara, Masato Sotome, Takuya Nomoto, Ryotaro Arita, Masao Nakamura, Daigo Miyajima
Summary: Researchers have found that the bulk photovoltaic effect (BPVE) in organic-inorganic hybrid perovskites (OIHPs) is not explained by the classical mechanism, but rather originates from the shift current mechanism. This discovery has significant implications for photodetector applications.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Tianchun Wang, Takuya Nomoto, Takashi Koretsune, Ryotaro Arita
Summary: We performed first-principles Eliashberg calculations for several conventional superconductors, investigating the importance of self-consistency in the calculation. By comparing the self-consistent results with the one-shot calculation results for the self-energy of electrons, we found that the difference between them becomes larger for systems with rapidly changing density of states around the Fermi level, such as those with van Hove singularities in pressurized hydrides.
JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS
(2023)
Article
Materials Science, Multidisciplinary
Shunsuke Kitou, Yoshio Kaneko, Yuiga Nakamura, Kunihisa Sugimoto, Yusuke Nomura, Ryotaro Arita, Yoshinori Tokura, Hiroshi Sawa, Taka-hisa Arima
Summary: By performing core differential Fourier synthesis (CDFS) analysis of high-energy X-ray diffraction data, we directly observe the distribution state of Mo 4d orbital electrons in a pyrochlore-type oxide Nd2Mo2O7 at subangstrom resolution. The obtained valence electron density (VED) distribution confirms the Mo4+ 4d2 orbital state, and a dip in the radial profile indicates a node of the 4d wave function. The VED distribution around the Nd site is attributed to the hybridization of neighboring O 2p with Nd 6s/6p/5d orbitals and the anisotropic Nd3+ 4f3 electrons, which cannot be explained by simple j-j or LS coupling models. This study demonstrates the usefulness of CDFS analysis in investigating orbital states in crystalline materials.
Article
Materials Science, Multidisciplinary
F. Schilberth, M. -C. Jiang, S. Minami, M. A. Kassem, F. Mayr, T. Koretsune, Y. Tabata, T. Waki, H. Nakamura, G. -Y. Guo, R. Arita, I. Kezsmarki, S. Bordacs
Summary: Through experimental and theoretical studies using broadband polarized reflectivity and magneto-optical Kerr effect spectroscopy, we have discovered giant anomalous Hall effect and magneto-optical activity in the magnet Co3Sn2S2 with topological nontrivial degeneracies, primarily generated by strongly tilted nodal-line segments around the Fermi energy. This finding is of significant importance for understanding the physical properties of magnetic topological materials.
Article
Materials Science, Multidisciplinary
Katsuhiro Tanaka, Takuya Nomoto, Ryotaro Arita
Summary: We investigate the tunneling magnetoresistance (TMR) effect using lattice models for magnetic tunnel junctions (MTJs). By analyzing the local density of states (LDOS) at the center of the barrier, we find that it qualitatively traces the TMR effect. The LDOS contains information on the electrodes and electron tunneling, allowing for a more precise evaluation of tunneling conductance. Furthermore, our findings show that the TMR effect in ferrimagnetic MTJs can be influenced by interfacial magnetic structures, which can also be captured by the LDOS.
Article
Materials Science, Multidisciplinary
Tatsuto Hatanaka, Takuya Nomoto, Ryotaro Arita
Summary: Transition metal dichalcogenides (TMDs) exhibit various magnetic structures through intercalation of other transition metal atoms. To understand the chemical trend of the magnetic properties, we conducted a first-principles study on 48 compounds with different hosts, guests, and composition ratios. By applying spin density functional theory and the local force method, we derived classical spin models that are consistent with experimental results and explained the chemical trend in terms of 3d orbital occupancy. These findings can guide the prediction of magnetic structures in yet-to-be-synthesized compounds.
Article
Materials Science, Multidisciplinary
Steffen Backes, Yuta Murakami, Shiro Sakai, Ryotaro Arita
Summary: Recent developments in quantum hardware and algorithms have enabled us to address problems in quantum chemistry and condensed-matter physics using current noisy intermediate-scale quantum devices. In this study, we demonstrate the solution of the dynamical mean-field theory (DMFT) impurity problem for the Hubbard-Holstein model on the IBM Quantum Processor Kawasaki. We encode both fermionic and bosonic degrees of freedom on the quantum device and use a Krylov variational quantum algorithm to obtain the impurity Green's function, achieving high accuracy.
Article
Materials Science, Multidisciplinary
Ryota Masuki, Takuya Nomoto, Ryotaro Arita, Terumasa Tadano
Summary: We propose a theory and calculation scheme for structural optimization at finite temperatures, based on the quasiharmonic approximation (QHA). The theory includes an efficient method for updating the interatomic force constants (IFCs) called IFC renormalization. Both cell shape and atomic coordinates are simultaneously optimized. We apply this theory to study the thermal expansion and pyroelectricity of GaN and ZnO, successfully reproducing experimental observations. We also present a general scheme to obtain accurate temperature dependence with constrained optimizations, reducing the number of effective degrees of freedom.
Article
Materials Science, Multidisciplinary
N. Matsuyama, T. Nomura, S. Imajo, T. Nomoto, R. Arita, K. Sudo, M. Kimata, N. D. Khanh, R. Takagi, Y. Tokura, S. Seki, K. Kindo, Y. Kohama
Summary: We have conducted magnetic torque and resistivity measurements on the centrosymmetric skyrmion host GdRu2Si2. Both de Haas-van Alphen and Shubnikov-de Haas oscillations were observed in the forced ferromagnetic phase. The angular dependence of the quantum oscillation frequencies can be explained by an ab initio calculation. The presence of a different de Haas-van Alphen oscillation frequency in the double-Q phase suggests a Fermi surface reconstruction due to coupling between localized spins and conduction electrons. Based on these experimental findings, the magnetic interactions in this system are discussed.
Article
Materials Science, Multidisciplinary
Yuki Yanagi, Hiroaki Kusunose, Takuya Nomoto, Ryotaro Arita, Michi-To Suzuki
Summary: We propose a systematic method for generating symmetry-adapted magnetic structures to analyze complex modulated magnetic structures. The method extends the generation scheme based on multipole expansion, which was previously only applicable for k = 0. By mapping the multipole magnetic alignments to the periodic crystal structure with the phase factor for wave vector k, symmetry-adapted magnetic structures with ordering vector k can be obtained. This method provides all magnetic bases compatible with irreducible representations under a k group for a given crystal structure and wave vector k.
