arXiv subjects

Sergei I. Mukhin

Publications and source records attributed to Sergei I. Mukhin.

12 recordsLinked to original sources

arXiv2025

Nanoscale lattice heterostructure in high Tc superconductors

Low temperature superconductivity was known since 1957 to be described by BCS theory for an effective single band metals controlled by the density of states at the Fermi level, very far from band edges, the electron phonon coupling, and the energy of the boson in the pairing interaction w0, but BCS has failed to predict high temperature superconductivity in different materials above about 23 K. High temperature superconductivity above 35 K since 1986 has been a matter of materials science where manipulating the lattice complexity of high temperature superconducting ceramic oxides (HTSC) has driven material scientists to grow new HTSC quantum materials up to 138K in HgBa2Ca2Cu3O8 (Hg1223) at ambient pressure and near room temperature in pressurized hydrides. This perspective covers the major results of materials scientist in these last 39 years investigating the role of lattice inhomogeneity detected in these new quantum complex materials. We highlight the nanoscale heterogeneity in these complex materials and elucidate their special role played in the physics for HTSC. Especially, it is pointed out that the geometry of lattice and charge complex heterogeneity at nanoscale is essential and intrinsic in the mechanism of rising quantum coherence at high temperature

cond-mat.supr-con↗

arXiv2023

Bragg's law for X-ray scattering by quantum thermodynamic time crystals, Q-balls, as manifestation of the mechanism of High-T$_c$ superconductivity

Proposed by the author Q-ball mechanism of the pseudogap state and high-Tc superconductivity in cuprates was recently supported by micro X-ray diffraction data in HgBa$_2$CuO$_{4+y}$. This provides a remarkable opportunity to investigate X-ray diffraction produced by the quantum thermodynamic time crystals, a direct embodiment of those are just the Euclidean Q-balls considered in the aforementioned theory. Simultaneously, it is also demonstrated that T-linear temperature dependence of electrical resistivity in the Q-ball phase arises due to scattering of electrons on the condensed charge/spin fluctuations inside the Q-balls. This gives a clue concerning possible mechanism of T-linear behaviour of electrical resistivity in the strange metal phase of high-T$_c$ cuprates. For this purpose the Green's functions of X-ray photons and fermions scattered by the Q-balls in the pseudogap phase of high-Tc superconductors are calculated using the Feynman diagrammatic technique. The Bragg's peaks intensity, provided by the imaginary part of the retarded photon Green's function, is calculated. In total, obtained results describe X-ray and electron scattering on the finite size Q-ball of CDW/SDW density, that oscillates with bosonic frequency $Ω=2πnT$ in Matsubara time, i.e. the quantum thermodynamic time crystal. It is found, that theoretical results are in good correspondence with X-ray diffraction data in HgBa$_2$CuO$_{4+y}$ reported recently. The T-linear dependence of electrical resistivity arises due to inverse temperature dependence of the Q-ball radius as function of temperature.

cond-mat.supr-con↗

arXiv2022

Euclidean Q-balls of fluctuating SDW/CDW in the 'nested' Hubbard model of high-T$_c$ superconductors as the origin of pseudogap and superconducting behaviors

The origin of the pseudogap (PG) phase and superconducting behaviors in high-Tc superconductors is proposed, based on the picture of Euclidean Q-balls formation, that carry Cooper/local-pair condensates inside their volumes. Unlike the baryonic Q-balls in supersymmetric standard model, the Euclidean Q-balls describe spin-/charge densities, that oscillate in Matsubara time, and are found in the 'nested' repulsive Hubbard model of high-Tc superconductors. Euclidean Q-balls arise due to global invariance of the effective theory under the phase rotation of the Fourier amplitudes of spin-/charge fluctuations, leading to conservation of the 'Noether charge' Q in Matsubara time. Due to local minimum of their potential energy at finite amplitude of the density fluctuations, the Q-balls provide greater binding energy of fermions into local/Cooper pairs than an exchange with infinitesimal lattice/charge/spin quasiparticles in the usual Frohlich mechanism. We show that below some temperature T* the Q-balls arise with a finite density of superconducting condensate inside them. The Q-balls expand their sizes to infinity at superconducting transition temperature Tc. Fermionic spectral gap inside the Q-balls arises in the vicinity of the 'nested' regions of the bare Fermi surface. Solutions are found analytically from the Eliashberg like equations with the 'nesting' wave vectors connecting different 'hot spots' on the bare Fermi surface. The experimental dependences of Uemura (1989) of Tc on superconducting density n_s, as well as of Li et al. (2010) of diamagnetic moment on magnetic field above Tc in cuprates follow naturally from the proposed theory. The 'breathing modes' of the Q-balls in Matsubara time, as well as sharp maximum in specific heat temperature dependence in the vicinity of the 1-st order phase transition into Q-balls gas phase are also predicted.

cond-mat.str-el↗

arXiv2019

Classes of metastable Thermodynamic Quantum Time Crystals

We found that thermodynamic quantum time crystals in fermi systems, defined as quantum orders oscillating periodically in the imaginary Matsubara time with zero mean, are metastable for two general classes of solutions. Mean-field time independent solutions proved to have lower free energy manifesting true thermodynamic equilibrium with either single or multiple (competing) charge, spin and superconducting symmetry breaking orders. The 'no-go' theorem is proven analytically for a case of long-range interactions between fermions in momentum space in electron-hole and Cooper channels.

cond-mat.str-el↗

arXiv2018

First order dipolar phase transition in the Dicke model with infinitely coordinated frustrating interaction

We found analytically a first order quantum phase transition in the Cooper pair box array of $N$ low-capacitance Josephson junctions capacitively coupled to a resonant photon in a microwave cavity. The Hamiltonian of the system maps on the extended Dicke Hamiltonian of $N$ spins one-half with infinitely coordinated antiferromagnetic (frustrating) interaction. This interaction arises from the gauge-invariant coupling of the Josephson junctions phases to the vector potential of the resonant photon field. In $N \gg 1$ semiclassical limit, we found a critical coupling at which ground state of the system switches to the one with a net collective electric dipole moment of the Cooper pair boxes coupled to superradiant equilibrium photonic condensate. This phase transition changes from the first to second order if the frustrating interaction is switched off. A self-consistently `rotating' Holstein-Primakoff representation for the Cartesian components of the total superspin is proposed, that enables to trace both the first and the second order quantum phase transitions in the extended and standard Dicke models respectively.

cond-mat.str-el↗

arXiv2013

Euclidian crystals in many-body systems: breakdown of Goldstone's theorem

In accord with Nambu-Goldstone theorem spontaneous breaking of a global continuous symmetry of the system by a mean-field order parameter causes appearance of massless Goldstone bosons, called also gapless Goldstone modes. It is demonstrated below that the theorem can be violated, i.e. the Goldstone modes possess finite gap, in the case of a novel "Euclidian crystal" (quantum ordered) state of interacting fermions, that was proposed recently {mukhin 2011}. This result may lead to the important consequences when considered in combination with another peculiar properties of the quantum order parameter (QOP) that where recently found: QOP's Green's function is finite and periodic along the Matsubara's axis, but Wick-rotated to the axis of real frequencies, possesses infinite periodic "chain" of \it{second order poles} along this axis {mukhin 2011}. This property of QOP leads to a remarkable physical consequence: \it{QOP does not scatter anything in Minkowski world} ! Hence, the present theory, we believe, may naturally indicate that two effects: "hidden order" revealed in ARPES spectra of fermi-excitations and "neutron resonance" feature at finite frequency in the magnetic (bosonic) excitations spectrum in lightly hole-doped copper oxides, could be emerging fingerprints of the Euclidian crystal state. A peculiar manifestation of the QOP self-consistent solution in the form of non-classical phonon states is described for an "electromagnetic Euclidian crystal" predicted recently {mukhin,fistul 2013} in the array of Josephson junctions coupled via electromagnetic field in the superconducting resonator. It is demonstrated that it may constitute a stable state of the system, that, for a particular quantum disordering model, exists inside the stability domain of the classical photonic condensate delimited by the critical value of the quantum disordering strength.

cond-mat.str-el↗

arXiv2009

Analytical derivation of thermodynamic properties of bolalipid membrane

We consider a model of bilayer lipid membrane with bola-lipids. The bola-lipid is modeled by linking tails of the hydrophobic chains in the opposite monolayers within bilayer as a first approximation. A number of thermodynamical characteristics are calculated analytically and compared with the ones of a regular membrane without chains linkage. Pronounced difference between lateral pressure profiles at the layers interface for linked and regular bilayer models is found. In the linked case, the lateral pressure mid-plane peak disappears, while the free energy per chain increases. We have also calculated distribution of the orientaional order parameter of linked chains across the bilayer, and found it is in contrast with the usual lipids case.

q-bio.BM↗

arXiv2009

Analytical derivation of thermodynamic properties of bilayer membrane with interdigitation

We consider a model of bilayer lipid membrane with interdigitation, in which the lipid tails of the opposite monolayers interpenetrate. The interdigitation is modeled by linking tails of the hydrophobic chains in the opposite monolayers within bilayer as a first approximation. A number of thermodynamical characteristics are calculated analytically and compared with the ones of a regular membrane without interdigitation. Striking difference between lateral pressure profiles at the layers interface for linked and regular bilayer models is found. In the linked case, the lateral pressure mid-plane peak disappears, while the free energy per chain increases. Within our model we found that in case of elongation of the chains inside a nucleus of e.g. liquid-condensed phase, homogeneous interdigitation would be more costly for the membrane's free energy than energy of the hydrophobic mismatch between the elongated chains and the liquid-expanded surrounding. Nonetheless, an inhomogeneous interdigitation along the nucleous boundary may occur inside a ``belt'' of a width that varies approximately with the hydrophobic mismatch amplitude.

q-bio.QM↗

arXiv2005

Phonon softening: "keyhole" into dynamic stripe-phase

The highly distinctive phonon self-energy dependences on the wave vector, calculated respectively for the static and dynamic stripe phase models of the underdoped cuprates are presented. The negative values of the real part of the on-stripe holes polarization loop lead to appearance of localized vibration states in the presence of well-separated stripes, relevant for underdoped cuprates. The localized modes split below the bare optical phonon frequencies exhibiting strong ``softening effect''. The calculated gap between localized and propagating phonon frequencies is practically doping independent in accord with the recent neutron measurements. The derived wave vector dependence of the phonon softening nicely coincides with anomalously shallow experimental curve in high-T$_c$ cuprates when stripe meandering is taken into account. Co-centering of the theoretical and experimental curves implicates statistics of on-stripe holes.

cond-mat.str-el↗

arXiv2005

Analytical derivation of lateral pressure profile from microscopic model of lipid bilayer

Field-theoretical method is proposed, that yields analytical expression for lateral pressure distribution across hydrophobic core of a bilayer lipid membrane. Lipid molecule, repelling entropicaly surrounding neighbors, is modeled as a flexible string embedded between confining walls in the self-consistent harmonic potential. At room temperature the pressure profile is expressed solely via lowest energy eigenfunctions of the operator of the string energy density. Analytical results compare favorably with molecular dynamics simulations. The theory is suited to study protein-lipid interaction.

cond-mat.soft↗

arXiv2003

Inter-layer slide and stress relaxation in a bilayer fluid membrane in the patch-clamp setting

Protein mechanosensitive channels (MS) are activated by tension transmitted through the lipid bilayer. We propose a theory of lateral stress relaxation in a bilayer lipid membrane exposed to external pressure pulse in the patch-clamp experimental setting. It is shown that transfer of lipid molecules into a strained region is thermodynamically advantageous due to local decrease of the stress. Considered stress relaxation mechanism may explain recent experimental observations (Davidson and Martinac 2003) of adaptation of MscL, bacterial mechanosensitive channel of large conductance, to sustained membrane stretch. Lateral stress relaxation in the monolayer, which controls the gating of MscL, triggers thermally activated transition of the open channels back to the closed state ("adaptation"). We evaluate the contribution of the hydrophobic mismatch between MS channel and lipid bilayer to the energy barrier separating open and closed states. Then, using the MscL thermodynamic model (Sukharev et. al, 1999), we estimate characteristic adaptation times at room temperature to be of the order of seconds, well in the range of the experimental data (Davidson and Martinac 2003). Estimated propagation time of the initial channel-opening stress over the whole membrane is 4-5 orders of magnitude shorter.

cond-mat.soft↗

arXiv1998

Stripe phase ordering as quantum interference phenomenon

A quantum interference mechanism of the stripe phase instability in quasi one-dimensional (1D) repulsive electron system is proposed. The leading spin-charge coupling term in Landau functional is derived microscopically. It is shown that away from half filling, periodic lattice potential causes cooperative condensation of the spin and charge superlattices, which constitute a 1D analogue of the experimentally observed quasi 2D structures in lanthanum cuprates and nickelates. Renormalization group analysis qualitatively supports the Hartree-Fock picture.

cond-mat↗