arXiv subjects

Firdous Haidar

Publications and source records attributed to Firdous Haidar.

4 recordsLinked to original sources

arXiv2026

Interplay of strain-induced axial gauge fields and intrinsic band-topology in the magnetoelectric conductivity of gapped nodal rings

We compute the magnetoelectric conductivity of a semimetal hosting an ideal gapped nodal ring (GNR) in three distinct planar-Hall configurations, in the simultaneous presence of an external electric field $\boldsymbol{E}$, a magnetic field $\boldsymbol{B}$, and a strain-induced axial pseudomagnetic field $\boldsymbol{B}_5$. The latter arises from a nonuniform lattice deformation and couples to antipodal points on the toroidal Fermi surface with opposite signs, reflecting its chiral nature. Extending our earlier analysis to include $\boldsymbol{B}_5$, we demonstrate how its vortex-like field lines --- co-aligned with the Berry curvature (BC) and orbital magnetic moment (OMM) --- imprint qualitatively distinct signatures on the conductivity tensor. In particular, this alignment causes the dot product of $\boldsymbol{B}_5$ with the BC or OMM-induced quantities to be angle-independent on the Fermi surface, generating a nonvanishing integral linear-in-$B_5$, which is not possible for isotropic nodal points harbouring BC-monopoles. We show that a part of the planar-Hall conductivity in the first set-up remains completely immune to strain, providing a strain-insensitive internal reference for topological transport. Our explicit analytical expressions offer concrete and experimentally-testable predictions for identifying strain-induced signatures in transport measurements on GNR materials.

cond-mat.mes-hall↗

arXiv2025

Direction-dependent linear response for gapped nodal-line semimetals in planar-Hall configurations

We compute the magnetoelectric conductivity for ideal nodal-line semimetals (NLSMs), with a finite but tiny mass-gap, in distinct planar-Hall set-ups. Each differing configuration results from the relative orientation of the nodal-ring's plane with respect to the plane spanned by the electric ($\mathbf E $) and magnetic ($\mathbf B$) fields. The net conductivity tensor has components comprising the Drude, anomalous-Hall, in-plane (with $\mathbf E$ and $\mathbf B$) longitudinal and transverse, and Lorentz-force-operator-induced parts. Our results feature the signatures of the inherent topology of a gapped NLSM, revealed through nonzero values of the Berry curvature and the orbital magnetic moment. In particular, we show that both of these vector fields, arising in the momentum space, give rise to terms of comparable magnitudes in the resulting response. Our explicit theoretical expressions will help identify unique signatures of NLSMs in contemporary experiments.

cond-mat.mes-hall↗

arXiv2025

Reflections of topological properties in the planar-Hall response for semimetals carrying pseudospin-1 quantum numbers

We continue our investigations of the nature of the linear-response tensors in planar-Hall and planar-thermal Hall configurations, involving three-dimensional nodal-point semimetals, by considering here nodes hosting pseudospin-1 quasiparticles. Such systems exemplify multifold semimetals, as they have three bands crossing at a nodal point. We derive the explicit expressions of the electric, thermoelectric, and thermal coefficients, when the nodes are subjected to the combined influence of an electric field (and/or temperature gradient) and a weak (i.e., nonquantizing) magnetic field. In order to have a complete description, we consider the effects of the Berry curvature and the orbital magnetic moment on an equal footing, both of which originate from the underlying topological features of the bandstructure. Going beyond our previous works, we determine the out-of-plane response comprising the intrinsic anomalous-Hall and the Lorentz-force-contributed currents, and chalk out the effects of internode scatterings as well. Our theoretical explorations shed light on the mechanisms of transport in multifold semimetals, which are being investigated in contemporary experiments.

cond-mat.mes-hall↗

arXiv2024

Linear response in planar Hall and thermal Hall setups for Rarita-Schwinger-Weyl semimetals

We investigate the nature of the linear-response tensors in planar Hall and planar thermal Hall setups, where we subject a Rarita-Schwinger-Weyl (RSW) semimetal to the combined influence of an electric field $\mathbf E $ (and/or temperature gradient $\nabla_{\mathbf r } T$) and a weak (i.e., nonquantizing) magnetic field $\mathbf B $. For computing the in-plane transport components, we have added an elastic deformation which gives rise to a chirality-dependent effective magnetic field $ \mathbf B^{\text{tot}} = \mathbf B + \chi \, \mathbf B_5 $, where $\chi $ is the chirality of an RSW node. We have included the effects of orbital magnetic moment (OMM), in conjunction with the Berry curvature (BC), both of which appear as a consequence of nontrivial topology of the bandstructure. Due to the presence of four bands, RSW semimetals provide a richer structure for obtaining the linear-response coefficients, compared to the Weyl semimetals. In particular, we have found that the OMM-contributed terms may oppose or add up to the BC-only parts, depending on which band we are considering. Last, but not the least, we have determined the out-of-plane response comprising the intrinsic anomalous-Hall and the Lorentz-force-contributed currents, whose nature corroborates the findings of some recent experimental results.

cond-mat.mes-hall↗