arXiv subjects

T. B. Mazitov

Publications and source records attributed to T. B. Mazitov.

4 recordsLinked to original sources

arXiv2026

Short-range magnetic order and multi-stage phase transitions in the easy-plane van der Waals magnet CrCl$_3$

We investigate the evolution of spin correlations and the nature of the multi-stage magnetic transition in the quasi-two-dimensional easy-plane van der Waals magnet $\rm CrCl_3$. By combining broadband ferromagnetic resonance (FMR) spectroscopy and DC SQUID magnetometry on mechanically exfoliated micro-flakes with non-local dynamical mean-field theory (DFT+DMFT) calculations, we analyze both long- and short range magnetic order in CrCl$_3$. Experimentally, SQUID and FMR measurements confirm the presence of the crossover to a spin polarized phase with the subsequent transition into an antiferromagnetic ground state upon cooling, but show robust short-range correlations at temperatures far above the magnetic ordering temperatures. Theoretically, we show the existence of highly stable local magnetic moments at room temperature, with a giant room temperature lifetime $τ$ of 130--300 ps due to a wide Mott bandgap. Below room temperature, a rapid growth of the in-plane correlation length $ξ$ signals the formation of strong short range magnetic order consistent with the experimental observations. We also obtain a temperature-driven crossover of the interlayer exchange interaction, which changes from positive (ferromagnetic) at high temperatures to negative (antiferromagnetic) in the low-temperature ordered phase.

cond-mat.str-el↗

arXiv2024

Local magnetic moment formation and Kondo screening in the presence of Hund exchange: the two-band Hubbard model analysis

We study formation and screening of local magnetic moments in the two-band Hubbard model in the presence of Hund exchange interaction using dynamic mean field theory approach. The characteristic temperatures of the formation, beginning and full screening of local magnetic moments are obtained from the analysis of temperature dependencies of the orbital, charge, and spin susceptibilities, as well as the respective instantaneous correlation functions. At half filling we find the phase diagram, which is similar to the single-orbital case with wide region of formation of local magnetic moments below the orbital Kondo temperature. Similarly to the single-orbital case, with decreasing temperature the screening of local magnetic moments is preceded by appearance of fermionic quasiparticles. In the two-band case the quasiparticles are however present also in some temperature region above the Mott insulating phase. At finite doping we find broad regime of presence of local magnetic moments, which coexist with incoherently or coherently moving holes. We also find, similarly to the half filled case, finite temperature interval in the doped regime, when the fermionic quasiparticles are formed, but do not yet screen local magnetic moments.

cond-mat.str-el↗

arXiv2022

The effect of local magnetic moments on spectral properties and resistivity near the interaction- and doping induced Mott transitions

We study the effect of the formation and screening of local magnetic moments on the temperature- and interaction dependencies of spectral functions and resistivity in the vicinity of the metal-insulator transition. We use the dynamical mean-field theory for the strongly correlated Hubbard model and associate the peculiarities of the above mentioned properties with those found for the local charge $χ_c$ and spin $χ_s$ susceptibilities. We show that at half filling the maximum of resistivity at a certain temperature $T^*$ corresponds to the appearance of central quasiparticle peak of the spectral function and entering the metallic regime with well defined fermionic quasiparticles. At the same time, the temperature of the crossover to the regime with screening of local magnetic moments, determined by the minimum of double occupation, is smaller than the temperature scale $T^*$ and coincides at half filling with the boundary $T_{β=1}(U)$ corresponding to the exponent of resistivity $β\equiv d\ln ρ/d\ln T=1$. Away from half filling we find weak increase of the temperature of the beginning and completion of the screening (i.e. Kondo temperature) of local magnetic moments, while the unscreened local magnetic moments exist only up to few percents of doping. In the low temperature regime $T<T_{β=1}$ simultaneous presence of itinerant and localized degrees of freedom yields almost linear temperature dependence of scattering rate and resistivity.

cond-mat.str-el↗

arXiv2022

Local magnetic moment formation and Kondo screening in the half filled two dimensional single band Hubbard model

We study formation of local magnetic moments in strongly correlated Hubbard model within dynamical mean field theory and associate peculiarities of temperature dependence of local charge $χ_c$ and spin $χ_s$ susceptibilities with different stages of local moment formation. Local maximum of temperature dependence of the charge susceptibility $χ_c$ is associated with beginning of local magnetic moments formation, while the minimum of the susceptibility $χ_c$ and double occupation, as well as low temperature boundary of the plateau of effective local magnetic moment $μ_{\rm eff}^2=Tχ_s$ temperature dependence are connected with full formation of local moments. We also obtain interaction dependence of the Kondo temperature $T_K$, which is compared to the fingerprint criterion of Phys. Rev. Lett. 126, 056403 (2021). Near the Mott transition the two criteria coincide, while further away from Mott transition the fingerprint criterion somewhat overestimates Kondo temperature. The relation of the observed features to the behavior of eigenvectors/eigenvalues of fermionic frequency-resolved charge susceptibility and divergences of irreducible vertices is discussed.

cond-mat.str-el↗