arXiv subjects

M. Selch

Publications and source records attributed to M. Selch.

8 recordsLinked to original sources

arXiv2026

Intrinsic (valley) thermal Hall conductivity of phonons in graphene for integer quantum Hall phases

We calculate the intrinsic contribution to the (valley) thermal Hall conductivity of phonons in (Semenoff-gapped) graphene in the quantum Hall regime where bulk electron thermal transport is suppressed. The (valley) thermal Hall transport of phonons considered here originates from a phonon (valley) Hall viscosity induced by electron (valley) Hall conductivity and viscosity via geometric electron-phonon coupling. The so generated phonon (valley) Hall viscosity is identified with the emergent (valley) Hall viscosity recently introduced in \textit{Phys. Lett. A} \textbf{595}, 132096 (2026). While our calculations refer to graphene, they may very well be generalized to other Dirac materials like group-VI transition metal dichalcogenides. We discuss the prospect of measuring the phonon thermal Hall conductivity in graphene-based heterostructures and estimate the corresponding valley response induced by electrons in the inversion symmetry broken phase.

cond-mat.mes-hall↗

arXiv2026

Valley Hall viscosity in the integer quantum Hall phases of (2+1)D Dirac materials

We calculate the valley-resolved Hall viscosity for Lorentz-invariant integer quantum Hall phases in Semenoff-semiconducting graphene-like systems at zero temperature. The Kubo formalism based discussion reported in Phys. Rev. B 100, 115421 (2019) revealed the divergence of single valley viscous Hall contributions for this case with only a valley-summed Hall viscosity being finite and therefore well-defined. Our approach to the Hall viscosity calculation is based on an equivalent Green function formulation within Wigner-Weyl calculus. We find that the previously identified divergence seems to be regularized to a finite value in a proper representation of the valley-resolved Hall viscosity in terms of energy eigenfunctions and eigenvalues. Together with the local Hall conductivity and its first nonlocal correction, reported as well in Phys. Rev. B 100, 115421 (2019), we extend the empirical relativistic Hoyos-Son formula to individual valleys. Both the original Hoyos-Son formula for Galilean invariant fluids and its relativistic extension to Dirac materials are found to be structurally identical for integer quantum Hall phases and expressible in terms of local electric and viscous Hall responses. In addition we evaluate the valley(-difference) Hall viscosity for biased Bernal bilayer graphene in the chiral fermion low energy approximation. Prospects of measuring valley Hall viscosity in nonlocal transport for mono- and bilayer graphene- and group-VI TMD-based devices are discussed.

cond-mat.mes-hall↗

arXiv2026

Emergent Hall viscosity in the integer quantum Hall phases of graphene-like systems

We explicitly distinguish Hall viscosity as defined relative to the strain field vs. relative to an emergent vielbein or metric field and discuss it for graphene-like systems. Aside from the gravitational or vielbein/metric related ``geometric'' Hall viscosity prevailing throughout the literature, a contribution proportional to the Hall conductivity, the ``electronic'' Hall viscosity, due to the emergent strain induced gauge field exists. We unify both contributions within the ``emergent'' Hall viscosity, determine it explicitly for graphene in the semimetal and Semenoff semiconducting phases for integer quantum Hall states and in the latter case compare it to its non-relativistic limit. Under these circumstances two topological invariants enter the emergent Hall viscosity in the presence of translational and rotational symmetry which we derive in the Green function representation of Wigner-Weyl calculus. We discuss experimental perspectives for extracting the emergent Hall viscosity.

cond-mat.mes-hall↗

arXiv2025

Non-renormalization of the fractional quantum Hall conductivity by interactions

We investigate the theory of the fractional quantum Hall effect (QHE) proposed a long time ago by Lopez and Fradkin \cite{Fradkin1991chern} to describe the principal Jain series. The magnetic fluxes of the statistical gauge field attached to electrons remain at rest in the reference frame moving together with the electron liquid. In the laboratory reference frame the electric field of the statistical gauge field forms and screens the external electric field. The fractional QHE conductivity appears as a consequence of this screening already on the mean field theory level. We consider a relativistic extension of the model, and propose an alternative description of the fractional QHE based on macroscopic motion of the electron liquid within the Zubarev statistical operator approach. It is this macroscopic motion of electrons which in this pattern gives rise to the fractional QHE. Within this approach we propose the proof to all orders of perturbation theory that the interaction corrections cannot change the above mentioned mean field theory result for the QHE conductivity.

cond-mat.mes-hall↗

arXiv2024

Effective Lagrangian for the macroscopic motion of Weyl fermions in $^3$He-A

We consider macroscopic motion of the normal component of superfluid $^3$He - A in global thermodynamic equilibrium within the context of the Zubarev statistical operator method. We formulate the corresponding effective theory in the language of the functional integral. The effective Lagrangian comprising macroscopic motion of fermionic excitations is calculated explicitly for the emergent relativistic fermions of the superfluid $^3$He - A phase immersed in a non-trivial bosonic background due to a space and time dependent matrix-valued vierbein featuring nonzero torsion as well as the Nieh-Yan anomaly. We do not consider the dynamics of the superfluid component itself and thereby its backreaction effects due to normal component macroscopic flow. It is being treated as an external background within which the emergent relativistic fermions of the normal component move. The matrix-valued vierbein formulation comprises an additional two dimensional internal spin space for the two axially charged Weyl fermions living at the Fermi points which may be replaced by one featuring a Dirac fermion doublet with a real valued vierbein, an axial Abelian gauge field and a spin connection gauge field mixing the Dirac and internal spin spaces. We carry out this change of description in detail and determine the constraints on the superfluid background as well as the the normal component motion as determined from the Zubarev statistical operator formalism in global thermodynamic equilibrium. As an application of the developed theory we consider macroscopic rotation around the axis of pure integer mass vortices. The corresponding thermodynamic quantities of the normal component are analyzed. Our formulation incorporates both superfluid background flow and macroscopic motion flow of the normal component and thereby enables an analysis of their interrelation.

cond-mat.mes-hall↗

arXiv2023

Effective lagrangian for the macroscopic motion of fermionic matter

We consider macroscopic motion of quantum field systems. Zubarev statistical operator allows to describe several types of motion of such systems in thermal equilibrium. We formulate the corresponding effective theory on the language of functional integral. The effective lagrangian is calculated explicitly for the fermionic systems interacting with dynamical gauge fields. Possible applications to physics of quark - gluon plasma are discussed.

hep-ph↗

arXiv2023

Hall conductivity as the topological invariant in magnetic Brillouin zone in the presence of interactions

Hall conductivity for the intrinsic anomalous quantum Hall effect in homogeneous systems is given by the topological invariant composed of the Green function depending on momentum of quasiparticle. This expression reveals correspondence with the mathematical notion of the degree of mapping. A more involved situation takes place for the quantum Hall effect in the presence of external magnetic field. In this case the mentioned expression remains valid if the Green function is taken in a specific representation, where it becomes the infinite - dimensional matrix \cite{Imai:1990zz} or if it is replaced by its Wigner transformation while ordinary products are replaced by the Moyal products \cite{ZW2019}. Both these expressions, unfortunately, are much more complicated and might be useless for the practical calculations. Here we represent the alternative representation for the Hall conductivity of a uniform system in the presence of constant magnetic field. The Hall conductivity is expressed through the Green function taken in Harper representation, when its nonhomogeneity is attributed to the matrix structure while functional dependence is on one momentum that belongs to magnetic Brillouin zone. Our consideration for the interacting systems is non - perturbative and is based on the Schwinger - Dyson equations truncated in a reasonable way. We demonstrate that in this approximation the expression for the Hall conductivity in Harper representation remains valid, where the interacting Green function is to be used instead of the non - interacting one. We, therefore, propose that the obtained expression may be used for the topological description of fractional quantum Hall effect.

cond-mat.mes-hall↗

arXiv2023

Gravastar-like black hole solutions in $q$-theory

We present a stationary spherically symmetric solution of the Einstein equations, with a source generated by a scalar field of $q$-theory. In this theory Riemannian gravity, as described by the Einstein - Hilbert action, is coupled to a three - form field that describes the dynamical vacuum. Formally it behaves like a matter field with its own stress - energy tensor, equivalent to a scalar field minimally coupled to gravity. The asymptotically flat solutions obtained to the field equations represent black holes. For a sufficiently large horizon radius the energy density is localized within a thin spherical shell situated just outside of the horizon, analogous to a gravastar. The resulting solutions to the field equations, which admit this class of configurations, satisfy existence conditions that stem from the Black Hole no - hair theorem, thanks to the presence of a region in space in which the energy density is negative.

gr-qc↗