Prediction of ferroelectricity-driven Berry curvature enabling charge- and spin-controllable photocurrent in tin telluride monolayers

Abstract

In symmetry-broken crystalline solids, pole structures of Berry curvature (BC) can emerge, and they have been utilized as a versatile tool for controlling transport properties. For example, the monopole component of the BC is induced by the time-reversal symmetry breaking, and the BC dipole arises from a lack of inversion symmetry, leading to the anomalous Hall and nonlinear Hall effects, respectively. Based on first-principles calculations, we show that the ferroelectricity in a tin telluride monolayer produces a unique BC distribution, which offers charge- and spin-controllable photocurrents. Even with the sizable band gap, the ferroelectrically driven BC dipole is comparable to those of small-gap topological materials. By manipulating the photon handedness and the ferroelectric polarization, charge and spin circular photogalvanic currents are generated in a controllable manner. The ferroelectricity in group-IV monochalcogenide monolayers can be a useful tool to control the BC dipole and the nonlinear optoelectronic responses.

Topological phonons in oxide perovskites controlled by light

“…In addition, previously unknown phonon-phonon and electron-phonon scattering mechanisms could arise from topological phonons, which may provide new insights into the enhanced superconductivity of SrTiO 3 ( 26 , 59 ). The emergence of Weyl phonons may be accompanied by other unique physical properties such as a pseudogauge field with a one-way propagating bulk mode ( 60 – 62 ), topological negative refraction ( 18 ), and nonlinear acoustic/optical responses ( 63 , 64 ), which can offer new routes for designing novel technologies like light-controlled neuromorphic computing in phononic systems ( 65 , 66 ). Our work shows that oxide perovskites provide a promising platform to explore all of these phenomena and applications.…”

Dynamical amplification of electric polarization through nonlinear phononics in 2D SnTe

“…is Berry curvature dipole (Λ) along a-direction,ẑ is the normal unit vector perpendicular to the plane made up of D and E, and f occ , τ are occupation of Bloch state and constant 10 . As discussed previously, the Berry curvature dipole directly scales with the polarization that measures the amount of inversion-symmetry breaking of the lattice 10,16 . Here we focus on the fact that the lattice distortion along the A u mode enhances the net in-plane polarization and leads to an increase in the Berry curvature dipole.…”

“…1d. Previous studies have suggested that this asymmetric Berry curvature can be attributed to the orbital Rashba effect 16 . Upon hole doping, this asymmetry in the Berry curvature grants sizable Berry curvature dipole (Λ y ) in the in the y-direction which can be manifested helicity-dependent second-order electro-optical responses 10,11 .…”

“…Besides optical responses of this inversion-asymmetric insulators, as mentioned above, the carrier dynamics in the hole-doped material have been intriguing in terms of nonlinear Hall effect and second-order responses 10,11,16 . The Berry curvature dipole have attracted intense interests for last couple of years 10,11 .…”

“…However, recent studies using optical pump, in terahertz or low infrared (IR) band, have expanded the scope of ferroelectricity to the nonequilibrium regime of driven states 3,4,14,15 . In this field, lowdimensional materials or nano-structured systems are more attractive in view of few-atom-scale local switching, which can lead to even enhanced non-volatility of state 3,4,[11][12][13][14][15][16][17] . An exemplary system in this area is the monolayer SnTe: the in-plane ferroelectricity of the atom-thick layer has Curie temperature of 270 K, three times higher than that of the corresponding threedimensional ferroelectric bulk structure (100 K) 13 .…”