A van der Waals interface that creates in-plane polarization and a spontaneous photovoltaic effect

Abstract

Van der Waals interfaces can be formed by layer stacking without regard to lattice constants or symmetries of individual building blocks. We engineered the symmetry of a van der Waals interface of tungsten selenide and black phosphorus and realized in-plane electronic polarization that led to the emergence of a spontaneous photovoltaic effect. Spontaneous photocurrent was observed along the polar direction and was absent in the direction perpendicular to it. The observed spontaneous photocurrent was explained by a quantum-mechanical shift current that reflects the geometrical and topological electronic nature of this emergent interface. The present results offer a simple guideline for symmetry engineering that is applicable to a variety of van der Waals interfaces.

Second-order magnetic responses in quantum magnets: Magnetization under ac magnetic fields

“…Nonlinear responses of charge degrees of freedom to electric fields have been extensively investigated [2,3]. Recent work along these lines includes high-harmonic generation (HHG) realized in solids [4][5][6][7][8][9][10] and bulk photovoltaic effect in noncentrosymmetric materials [11][12][13][14][15][16][17]. These nonlinear phenomena are closely related to electronic band structures and collective excitations [18][19][20][21][22][23][24][25].…”

Topological charge pumping in quasiperiodic systems characterized by Bott index

“…The structure of quasiperiodic crystals can be regarded as a projection of higher-dimensional-crystalline structure [13,14], and would allow us to access the physics of higherdimensional-space that is usually inaccessible in threedimensional crystals. Recently, van der Waals (vdW) heterostructure of two dimensional thin films has been realized and intensively studied, including twisted bilayer graphenes [15][16][17] and interface of transition metal dichalcogenides [18,19]. VdW heterostructures made of different crystals can be also considered as quasiperiodic systems [19,20], which provides an interesting platform for quasiperiodic structures due to their controllability and a rich variety of material combinations.…”

“…Recently, van der Waals (vdW) heterostructure of two dimensional thin films has been realized and intensively studied, including twisted bilayer graphenes [15][16][17] and interface of transition metal dichalcogenides [18,19]. VdW heterostructures made of different crystals can be also considered as quasiperiodic systems [19,20], which provides an interesting platform for quasiperiodic structures due to their controllability and a rich variety of material combinations. * mao@g.ecc.u-tokyo.ac.jp Topology and geometry in quasiperiodic systems are an interesting subject.…”

Multiple Heterojunction System of Boron Nitride‐Graphene/Black Phosphorene as Highly Efficient Solar Cell

“…In particular, the method of constructing a heterojunction can not only improve the stability of BP, but also further enhance its electronic performance. [28][29][30][31][32] Based on the above-mentioned excellent characteristics of BN-GR, perhaps BN-GR is a good modified material for BP, which may have unexpected performance improvement effects.…”