RESUMEN
We report for the first time the synthesis of [C(NH2)3]Cr(HCOO)3 stabilizing Cr2+ in formate perovskite, which adopts a polar structure and orders magnetically below 8 K. We discuss in detail the magnetic properties and their coupling to the crystal structure based on first-principles calculations, symmetry, and model Hamiltonian analysis. We establish a general model for the orbital magnetic moment of [C(NH2)3]M(HCOO)3 (M = Cr, Cu) based on perturbation theory, revealing the key role of the Jahn-Teller distortions. We also analyze their spin and orbital textures in k-space, which show unique characteristics.
RESUMEN
We studied the magneto-optical Kerr effect (MOKE) of two-dimensional (2D) heterostructure CrI3/In2Se3/CrI3 using density functional theory calculations and symmetry analysis. The spontaneous polarization in the In2Se3 ferroelectric layer and the antiferromagnetic ordering in CrI3 layers break the mirror and the time-reversal symmetry, thus activating MOKE. We show that the Kerr angle can be reversed by either the polarization or the antiferromagnetic order parameter. Our results suggest that ferroelectric and antiferromagnetic 2D heterostructures could be exploited for ultracompact information storage devices, where the information is encoded by the two ferroelectric or the two time-reversed antiferromagnetic states and the read-out is performed optically by MOKE.
RESUMEN
The reduced symmetry in strong spin-orbit coupling materials such as transition metal ditellurides (TMDTs) gives rise to non-trivial topology, unique spin texture, and large charge-to-spin conversion efficiencies. Bilayer TMDTs are non-centrosymmetric and have unique topological properties compared to monolayer or trilayer, but a controllable way to prepare bilayer MoTe2 crystal has not been achieved to date. Herein, we achieve the layer-by-layer growth of large-area bilayer and trilayer 1T' MoTe2 single crystals and centimetre-scale films by a two-stage chemical vapor deposition process. The as-grown bilayer MoTe2 shows out-of-plane ferroelectric polarization, whereas the monolayer and trilayer crystals are non-polar. In addition, we observed large in-plane nonlinear Hall (NLH) effect for the bilayer and trilayer Td phase MoTe2 under time reversal-symmetric conditions, while these vanish for thicker layers. For a fixed input current, bilayer Td MoTe2 produces the largest second harmonic output voltage among the thicker crystals tested. Our work therefore highlights the importance of thickness-dependent Berry curvature effects in TMDTs that are underscored by the ability to grow thickness-precise layers.
