Finite-q photon-drag shift current in two-dimensional massive chiral Dirac fermions
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| Format: | Preprint |
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2026
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| author | Rofii Hasdeo, Eddwi |
| author_facet | Rofii Hasdeo, Eddwi |
| contents | We investigate the photon-drag shift current in an isotropic single-valley two-dimensional massive chiral Dirac model with chirality index $J=1,2,3$ by directly evaluating the full finite-$q$ non-vertical response beyond the perturbative small-$q$ regime. Our central result is that chirality qualitatively reorganizes the sign topology of the finite-$q$ photocurrent $\mathbf{ j}(\mathbf{ q})$. For $J=1$, the photocurrent remains broadly positive, whereas higher-chirality sectors ($J \ge 2$) generically develop internal zero-current contours and sign reversals within the kinematically allowed region. We further show that the photocurrent is symmetry-constrained to be purely transverse, $\mathbf{j}(\mathbf{q}) \propto \hat{\mathbf{z}}\times\mathbf{q}$, and vanishes in the strictly vertical-transition limit $q=0$ in centrosymmetric systems. Pauli blocking further shapes the response by selecting the active portion of the resonance contour, while its extinction at large $Δ$ or $q$ follows from a simple kinematic cutoff. These results establish the isotropic massive chiral Dirac problem as a symmetry-controlled benchmark for chirality-dependent finite-$q$ shift currents. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2605_07856 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Finite-q photon-drag shift current in two-dimensional massive chiral Dirac fermions Rofii Hasdeo, Eddwi Mesoscale and Nanoscale Physics We investigate the photon-drag shift current in an isotropic single-valley two-dimensional massive chiral Dirac model with chirality index $J=1,2,3$ by directly evaluating the full finite-$q$ non-vertical response beyond the perturbative small-$q$ regime. Our central result is that chirality qualitatively reorganizes the sign topology of the finite-$q$ photocurrent $\mathbf{ j}(\mathbf{ q})$. For $J=1$, the photocurrent remains broadly positive, whereas higher-chirality sectors ($J \ge 2$) generically develop internal zero-current contours and sign reversals within the kinematically allowed region. We further show that the photocurrent is symmetry-constrained to be purely transverse, $\mathbf{j}(\mathbf{q}) \propto \hat{\mathbf{z}}\times\mathbf{q}$, and vanishes in the strictly vertical-transition limit $q=0$ in centrosymmetric systems. Pauli blocking further shapes the response by selecting the active portion of the resonance contour, while its extinction at large $Δ$ or $q$ follows from a simple kinematic cutoff. These results establish the isotropic massive chiral Dirac problem as a symmetry-controlled benchmark for chirality-dependent finite-$q$ shift currents. |
| title | Finite-q photon-drag shift current in two-dimensional massive chiral Dirac fermions |
| topic | Mesoscale and Nanoscale Physics |
| url | https://arxiv.org/abs/2605.07856 |