References of "Võ Tiến, Phong"
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See detailNetwork model for periodically strained graphene
De Beule, Christophe UL; Võ Tiến, Phong; Mele, Eugene John

in Physical Review. B (2023), 107

The long-wavelength physics of monolayer graphene in the presence of periodic strain fields has a natural chiral scattering network description. When the strain field varies slowly compared to the ... [more ▼]

The long-wavelength physics of monolayer graphene in the presence of periodic strain fields has a natural chiral scattering network description. When the strain field varies slowly compared to the graphene lattice and the effective magnetic length of the induced valley pseudomagnetic field, the low-energy physics can be understood in terms of valley-polarized percolating domain-wall modes. Inspired by a recent experiment, we consider a strain field with threefold rotation and mirror sym- metries but without twofold rotation symmetry, resulting in a system with the connectivity of the oriented kagome network. Scattering processes in this network are captured by a symmetry- constrained phenomenological S matrix. We analyze the phase diagram of the kagome network, and show that the bulk physics of the strained graphene can be qualitatively captured by the network when we account for a percolation transition at charge neutrality. We also discuss the limitations of this approach to properly account for boundary physics. [less ▲]

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See detailRose Patterns in the Nonperturbative Current Response of Two-Dimensional Superlattices
De Beule, Christophe UL; Võ Tiến, Phong; Mele, Eugene John

E-print/Working paper (2023)

In two-dimensional superlattice materials, the nonlinear current response to a large applied electric field can feature a strong angular dependence. This nonperturbative regime encodes information about ... [more ▼]

In two-dimensional superlattice materials, the nonlinear current response to a large applied electric field can feature a strong angular dependence. This nonperturbative regime encodes information about the band dispersion and Berry curvature of isolated electronic Bloch minibands. Within the relaxation-time approximation, we obtain analytic expressions for the current in a band-projected theory with time-reversal and trigonal symmetry, up to infinite order in the driving field. For a fixed field strength, the dependence of the current on the direction of the applied field is given by rose curves whose petal structure is symmetry constrained and is obtained from an expansion in real-space translation vectors. We illustrate our theory with calculations on periodically-buckled graphene and twisted double bilayer graphene, wherein the discussed physics can be accessed at experimentally-relevant field strengths. [less ▲]

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