A5068841671- Advanced Condensed Matter Physics
- Physics of Superconductivity and Magnetism
- Magnetic and transport properties of perovskites and related materials
- Rare-earth and actinide compounds
- Magnetic properties of thin films
- X-ray Spectroscopy and Fluorescence Analysis
- Quantum and electron transport phenomena
- Nuclear materials and radiation effects
- Theoretical and Computational Physics
- Inorganic Fluorides and Related Compounds
- Cold Atom Physics and Bose-Einstein Condensates
- Multiferroics and related materials
- Copper-based nanomaterials and applications
- Atomic and Subatomic Physics Research
- Advanced Chemical Physics Studies
- Molecular Junctions and Nanostructures
- Topological Materials and Phenomena
- Spectroscopy and Quantum Chemical Studies
- Quantum, superfluid, helium dynamics
- Transition Metal Oxide Nanomaterials
- DNA and Nucleic Acid Chemistry
- Magnetic Properties and Synthesis of Ferrites
- Catalysis and Oxidation Reactions
- Superconductivity in MgB2 and Alloys
- Iron oxide chemistry and applications
Dubna State University
2021
Max Planck Institute for the Physics of Complex Systems
2000-2020
Joint Institute for Nuclear Research
2000-2020
Max Planck Society
1993-2013
Max Planck Institute for Chemical Physics of Solids
2001-2009
Max Planck Institute for Solid State Research
1993
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...
We report on results of specific heat measurements single crystals the frustrated quasi-2D spin-1/2 antiferromagnet Cs2CuCl4 (T(N)=0.595 K) in external magnetic fields B<12 T and for temperatures T>30 mK. Decreasing B from high leads to closure field-induced gap magnon spectrum at a critical field Bc approximately = 8.51 phase transition is clearly seen below Bc. In vicinity Bc, boundary well described by power law Tc(B) proportional, variant (Bc-B)(1/phi), with measured exponent phi =1.5....
In the search for topological phases in correlated electron systems, materials with $5d$ transition-metal ions, particular iridium-based pyrochlores ${A}_{2}$Ir${}_{2}$O${}_{7}$, provide fertile grounds. Several states have been predicted but actual realization of such is believed to critically depend on strength local potentials arising from distortions IrO${}_{6}$ cages. We test this hypothesis by measuring resonant inelastic x-ray scattering electronic level splittings $A=\text{Y}$, Eu...
The magnetic behavior of the low-dimensional vanadium oxides ${\mathrm{Sr}}_{2}{\mathrm{V}}_{3}{\mathrm{O}}_{9}$ and ${\mathrm{Ba}}_{2}{\mathrm{V}}_{3}{\mathrm{O}}_{9}$ was investigated by means susceptibility specific heat measurements. In both compounds, results can be very well described an $S=\frac{1}{2}$ Heisenberg antiferromagnetic chain with intrachain exchange $J=82$ 94 K in ${\mathrm{Ba}}_{2}{\mathrm{V}}_{3}{\mathrm{O}}_{9},$ respectively....
The two-band Emery model has been reduced to an effective singlet-triplet describe the low-energy electronic properties of ${\mathrm{CuO}}_{2}$ plane in oxide superconductors. Hamiltonian is written terms Hubbard operators, projecting onto local singlet and triplet states a doped hole. projection method for two-time Green's functions (GF's) applied obtain band structure density paramagnetic state. It found that mainly oxygen character located between antibonding copper nonbonding bands. part...
The chainlike spin-$1/2$ antiferromagnetic vanadium oxide compound ${\mathrm{Sr}}_{2}{\mathrm{V}}_{3}{\mathrm{O}}_{9}$ is studied by electron spin resonance (ESR) with special attention to the space distribution of Dzyaloshinskii-Moriya (DM) vector along magnetic chains. angular variation and temperature dependence ESR linewidth measured in two different planes a single crystal range 4.2--500 K. data interpretation based on combined application standard theory for low-dimensional systems an...
In an attempt to explain inelastic neutron scattering data for $\mathrm{Li}{\mathrm{V}}_{2}{\mathrm{O}}_{4}$, the dynamical spin susceptibility $\ensuremath{\chi}(\mathbf{Q},\ensuremath{\omega})$ at zero temperature is calculated. The starting point a weak coupling approach based on local-density approximation band structure that material. It supplemented by random-phase treatment of local on-site interactions and contains adjustable parameter. Due geometrically frustrated lattice structure,...
In a recent work devoted to the magnetism of Li2CuO2, Shu et al (2017 New J. Phys. 19, 023026) have proposed 'simplified' unfrustrated microscopic model that differs considerably from models refined through decades prior work. We show is at odds with known experimental data, including reported magnetic susceptibility χ(T) data up 550 K. Using an 8th order high-temperature expansion for χ(T), we Li2CuO2 are consistent derived inelastic neutron scattering studies. also establish T-range...
Ytterbium-based delafossites with effective S=1/2 moments are investigated intensively as candidates for quantum spin-liquid ground states. While the synthesis of related cerium compounds has also been reported,many important details concerning their crystal, electronic, and magnetic structures unclear. Here we analyze system KCeO2, combining complementary theoretical methods. The lattice geometry was optimized band structure using density functional theory extended to level a GGA+U...
A Reply to the Comment by S. E. Sebatian et al.Received 18 January 2006DOI:https://doi.org/10.1103/PhysRevLett.96.189704©2006 American Physical Society
A phenomenological description for the dynamical spin susceptibility $χ({\bf q},ω;T)$ observed in inelastic neutron scattering measurements on powder samples of LiV$_2$O$_4$ is developed terms parametrized self-consistent renormalization (SCR) theory fluctuations. Compatible with previous studies at $T\to 0$, a peculiar distribution ${\bf q}$-space strongly enhanced and slow fluctuations $q \sim Q_c \simeq$ 0.6 $Å^{-1}$ involved to derive mode-mode coupling term entering basic equation SCR...
Based on the realistic spin Hamiltonian for frustrated quasi-two-dimensional spin-$1∕2$ antiferromagnet ${\mathrm{Cs}}_{2}{\mathrm{CuCl}}_{4}$, a three-dimensional ordering in applied magnetic field $B$ near saturation value ${B}_{c}$ is studied within magnon Bose-Einstein condensation scenario. Using hard-core boson formulation of model, strongly anisotropic dispersion ${\mathrm{Cs}}_{2}{\mathrm{CuCl}}_{4}$ calculated. In dilute limit ${B}_{c}$, constraint results an effective interaction...
The 3d electron spinel compound LiV2O4 exhibits heavy fermion behaviour below 30K which is related to antiferromagnetic spin fluctuations strongly enhanced in an extended region of momentum space. This mechanism explains thermodynamic quantities and nearly critical NMR relaxation the framework selfconsistent renormalization (SCR) theory. Here we show that low-T Fermi liquid resistivity a deviation from this behavior for higher T may also be understood within context. We calculate temperature...
A theory of superexchange in the mixed-valent-layer compound ${\mathrm{NaV}}_{2}{\mathrm{O}}_{5}$ is presented that provides a consistent description exchange both disordered and charge-ordered states. Starting from results band structure calculations for ${\mathrm{NaV}}_{2}{\mathrm{O}}_{5},$ first an underlying electronic model ladder unit Trellis lattice formulated. By using molecular orbital representation intrarung states, second-order perturbation procedure developed effective...
The antiferromagnetic insulating cuprate ${\mathrm{Ba}}_{3}{\mathrm{Cu}}_{2}{\mathrm{O}}_{4}{\mathrm{Cl}}_{2}$ contains folded ${\mathrm{CuO}}_{2}$ chains with four magnetic copper ions $(S=1/2)$ per unit cell. An underlying multiorbital Hubbard model is formulated and the superexchange theory developed to derive an effective spin Hamiltonian for this cuprate. resulting involves a Dzyaloshinskii-Moriya term more weak symmetric anisotropic exchange besides isotropic interaction. corresponding...
To treat effects of electron correlations in geometrically frustrated pyrochlore and checkerboard lattices, an extended single-orbital Hubbard model with nearest-neighbor hopping $\ensuremath{\sim}t$ Coulomb repulsion $\ensuremath{\sim}V$ is applied. Infinite on-site repulsion, $U\ensuremath{\rightarrow}\ensuremath{\infty}$, assumed, thus double occupancies sites are forbidden completely the present study. A variational Gutzwiller-type approach to examine due short-range $V$ interaction a...
A Reply to the Comment by D. L. Mills.Received 18 April 2006DOI:https://doi.org/10.1103/PhysRevLett.98.039702©2007 American Physical Society
Low-frequency spin fluctuation dynamics in paramagnetic spinel LiV2O4, a rare 3d-electron heavy-fermion system, is investigated. A parametrized self-consistent renormalization (SCR) theory of the dominant AFM fluctuations developed and applied to describe temperature pressure dependences low-T nuclear spin–lattice relaxation rate 1/T1 this material. The experimental data for available down ∼1 K are well reproduced by SCR theory, showing development as metal approaches magnetic instability...
The quantum-mechanical model proposed earlier by Skourtis and Nitzan (J. of Chem. Phys. 119, (2003) 6271) to describe a charge transfer in fragment artificial DNA molecule has been numerically investigated. current rationale for the is carried out values its parameters are indicated. Within this model, description transport hole carrier based on solutions time-dependent Schrödinger equation including damping effects. non-unitary dynamics treated us within framework theory continuous quantum...