A5089437525- Physics of Superconductivity and Magnetism
- Advanced Condensed Matter Physics
- Quantum and electron transport phenomena
- Quantum many-body systems
- Magnetic and transport properties of perovskites and related materials
- Geotechnical Engineering and Soil Stabilization
- Theoretical and Computational Physics
- Organic and Molecular Conductors Research
- Perovskite Materials and Applications
- Geotechnical Engineering and Soil Mechanics
- Cold Atom Physics and Bose-Einstein Condensates
- Magnetism in coordination complexes
- Magnetic properties of thin films
- Multiferroics and related materials
- DNA and Nucleic Acid Chemistry
- Topological Materials and Phenomena
- Grouting, Rheology, and Soil Mechanics
- Geotechnical Engineering and Underground Structures
- Advanced NMR Techniques and Applications
- Iron-based superconductors research
- Superconducting Materials and Applications
- Advanced biosensing and bioanalysis techniques
- Advanced Photocatalysis Techniques
- Chemical Synthesis and Analysis
- Black Holes and Theoretical Physics
Leibniz Institute for Solid State and Materials Research
2016-2025
TU Dresden
2016-2025
Civil Engineering Research Institute for Cold Region
2004-2016
Tokushima University
2013
Max Planck Society
2006-2011
Max Planck Institute for the Physics of Complex Systems
2006-2011
Fukuoka Institute of Technology
2010-2011
Leibniz Association
2011
Kyoto University
1991-2009
Hiroshima University
2005-2007
We report a $^{35}$Cl nuclear magnetic resonance study in the honeycomb lattice, $\alpha$-RuCl$_3$, material that has been suggested to potentially realize Kitaev quantum spin liquid (QSL) ground state. Our results provide direct evidence $\alpha$-RuCl$_3$ exhibits field-induced QSL. For fields larger than $\sim 10$ T spin-gap opens up while lines remain sharp, evidencing spins are disordered and locally fluctuating. The gap increases linearly with increasing field, reaching $\sim50$ K at 15...
Abstract Large anisotropic exchange in 5 d and 4 oxides halides open the door to new types of magnetic ground states excitations, inconceivable a decade ago. A prominent case is Kitaev spin liquid, host remarkable properties such as protection quantum information emergence Majorana fermions. Here we discuss promise for spin-liquid behavior honeycomb halide α -RuCl 3 . From advanced electronic-structure calculations, find that interaction ferromagnetic, iridium oxides, indeed defines largest...
Na2IrO3, a honeycomb 5d5 oxide, has been recently identified as potential realization of the Kitaev spin lattice. The basic feature this model is that for each three metal–metal links emerging out metal site, interaction connects only components perpendicular to plaquette defined by magnetic ions and two bridging ligands. fact reciprocally orthogonal are coupled along different leads strong frustration effects nontrivial physics. While experiments indicate zigzag antiferromagnetic order in...
Using the density matrix renormalization group, we determine phase diagram of spin-1/2 Heisenberg antiferromagnet on a honeycomb lattice with nearest-neighbor interaction J(1) and frustrating, next-nearest-neighbor exchange J(2). As frustration increases, ground state exhibits Néel, plaquette, dimer orders, critical points at J(2)/J(1) = 0.22 0.35. We observe that both spin gap corresponding order parameters vanish continuously points, indicating presence deconfined quantum criticality.
We analyze the measured optical conductivity spectra using density-functional-theory-based electronic structure calculation and density-matrix renormalization group of an effective model. show that, in contrast to a conventional description, Bose-Einstein condensation preformed excitons occurs Ta$_2$NiSe$_5$, despite fact that noninteracting band is band-overlap semimetal rather than small band-gap semiconductor. The system above transition temperature therefore not semimetal, but state with...
We determine the ground-state phase diagram of one-dimensional half-filled Hubbard model with on-site (nearest-neighbor) repulsive interaction U (V) and nearest-neighbor hopping t using density-matrix renormalization group technique. Based on results excitation gaps, Luttinger-liquid exponents, bond-order-wave (BOW) order parameter, we confirm that BOW appears in a substantial region between charge-density-wave (CDW) spin-density-wave phases. Each boundary is determined by multiple means it...
In quantum magnetism spin dimers are typically associated with spin-singlet states. To date, $triplet$ $dimerization$ has not been observed in any 3D or quasi-2D material. With this mind we here discuss the electronic structure of spin-orbit driven $5d^5$ Mott insulator Li$_2$IrO$_3$, a honeycomb-lattice system two crystallographically inequivalent Ir-Ir bonds. From $ab$ $initio$ many-body calculations find that, while both Heisenberg and Kitaev couplings present, magnetic interactions...
The rich physics manifested by 5d oxides falls outside the Mott-Hubbard paradigm used to successfully explain electronic and magnetic properties of 3d oxides. Much consideration has been given extent which strong spin-orbit coupling (SOC), in limit increased bandwidth reduced electron correlation, drives formation novel states, as through existence metal-insulator transitions (MITs). SOC is believed play a dominant role 5d5 systems such iridates (Ir4+), undergoing MITs may or not be...
Temperature-pressure phase diagram of the Kitaev hyperhoneycomb iridate $\beta$-Li$_2$IrO$_3$ is explored using magnetization, thermal expansion, magnetostriction, and muon spin rotation ($\mu$SR) measurements, as well single-crystal x-ray diffraction under pressure ab initio calculations. The Neel temperature increases with slope 0.9 K/GPa upon initial compression, but reduction in polarization field $H_c$ reflects a growing instability incommensurate order. At 1.4 GPa, ordered state breaks...
Glucose can react nonenzymatically with amino groups of proteins to form covalent Amadori products. With time these adducts undergo further rearrangements irreversible advanced glycosylation endproducts (AGE), which accumulate protein age. A specific AGE, 2-(2-furoyl)-4(5)-(2-furanyl)-1H-imidazole (FFI), has been identified on in vivo. We have recently shown that a macrophage receptor specifically recognizes and internalizes modified by AGE such as FFI, thus preferentially degrading...
We present a detailed study in the paramagnetic regime of frustrated $s$ = 1/2 spin-compound linarite, PbCuSO$_4$(OH)$_2$, with competing ferromagnetic nearest-neighbor and antiferromagnetic next-nearest-neighbor exchange interactions. Our data reveal highly anisotropic values for saturation field along crystallographic main directions, $\sim$ 7.6, 10.5 8.5\,T $a$, $b$, $c$ axes, respectively. In regime, this behavior is explained mainly by anisotropy \textit{g}-factor but leaving room an...
We show how the general and basic asymmetry between two fundamental degrees of freedom present in strongly correlated oxides, spin orbital, has very profound repercussions on elementary orbital excitations. Whereas magnons remain largely unaffected, orbitons become inherently coupled with fluctuations spin-orbital models antiferromagnetic ferroorbital ordered ground states. The composite orbiton-magnon modes that emerge fractionalize again one dimension, giving rise to separation peculiar...
Very recently a quantum liquid was reported to form in H_{3}LiIr_{2}O_{6}, an iridate proposed be close realization of the Kitaev honeycomb model. To test this assertion we perform detailed chemistry calculations determine magnetic interactions between Ir moments. We find that weakly bond dependent ferromagnetic exchange dominates over other couplings, but still is substantially lower than Na_{2}IrO_{3}. This reduction caused by peculiar position interlayer species: removing hydrogen cations...
The Tomonaga--Luttinger parameter $K_{\rho}$ determines the critical behavior in quasi one-dimensional correlated electron systems, e.g., exponent $\alpha$ for density of states near Fermi energy. We use numerical density-matrix renormalization group method to calculate from slope density-density correlation function momentum space at zero wave vector. check accuracy our new approach against exact results Hubbard and XXZ Heisenberg models. determine phase diagram extended model quarter...
The grand canonical numerical analysis recently developed for quantum many-body systems on a finite cluster [C. Hotta and N. Shibata, Phys. Rev. B 86, 041108(R) (2012)] is the technique to efficiently obtain physical quantities in an applied field. There, observables are continuous real functions of fields, mimicking their thermodynamic limit, even when small adopted. We develop theory explain mechanism this based deformation Hamiltonian. spatially scales down energy unit from system center...
A recently performed resonant inelastic x-ray scattering experiment (RIXS) at the copper ${L}_{3}$ edge in quasi-one-dimensional Mott insulator Sr${}_{2}$CuO${}_{3}$ has revealed a significant dispersion of single-orbital excitation (orbiton). This large and unexpected orbiton been explained using concept spin-orbital fractionalization which orbiton, is intrinsically coupled to spinon this material, liberates itself from due strictly one-dimensional nature its motion. Here, we investigate...
Due to the combination of a substantial spin-orbit coupling and correlation effects, iridium oxides hold prominent place in search for novel quantum states matter, including, e.g., Kitaev spin liquids topological Weyl states. We establish promise very recently synthesized hyper-honeycomb iridate $\beta$-Li2IrO3 this regard. A detailed theoretical analysis reveals presence large ferromagnetic first-neighbor interactions, while second-neighbor antiferromagnetic Heisenberg exchange drives...
We investigate the spin-1/2 Heisenberg model on delta chain (sawtooth chain) with ferromagnetic nearest-neighbor and antiferromagnetic next-neighbor interactions. For a special ratio between these interactions there is class of exact ground states formed by localized magnons state macroscopically degenerate. The degree this degeneration found analytically. It shown that residual entropy per spin ${s}_{0}=\frac{1}{2}ln\phantom{\rule{0.16em}{0ex}}2$. An important feature sharp decrease gaps...
Magnetic ordering of PbMnTeO6 crystallizing in the chiral noncentrosymmetric P312 space group has been experimentally investigated by high-resolution neutron powder diffraction (NPD) and theoretically high-temperature expansion, density matrix renormalization group, linear spin-wave theory approaches. Processing low-temperature NPD data showed that, to describe rather complex spin PbMnTeO6, two incommensurate modulations determined propagation vectors k1 k2 should be used. The observed...
We study the Hubbard model at half band-filling on a Bethe lattice with infinite coordination number in paramagnetic insulating phase zero temperature. use dynamical mean-field theory (DMFT) mapping to single-impurity Anderson bath whose properties have be determined self-consistently. For controlled and systematic implementation of self-consistency scheme we fixed-energy (FE) approach DMFT. In FE-DMFT onset width bands are adjusted self-consistently but energies levels kept fixed relatively...