On the basis of first-principles calculations, the systematic researches on the structure, magnetism and ferroelectricity of VOBr2 monolayer are carried out in the present work. The calculation results indicate that a spontaneous ferroelectric distortion will take place at low temperature, causing the structure of VOBr2 to transform from a centrosymmetric paraelectric phase to a ferroelectric one. In contrast with its sister compound VOI2, the dimerization of V is unstable in VOBr2 and may quench the local magnetic moment on V ions. Additionally, the easy magnetization axis of VOBr2 monolayer is in-plane along the a-axis, the magnetic coupling between adjacent local moments are antiferromagnetic both along a and b-axis. Moreover, the ferroelectric displacement of V ions occurs in the a-axis, along V-O-V chains direction, resulting in a polarization of about 40 uC/cm2. Compared with the ferro-to-paraelectric reversal pathway, the energy barrier can be effectively reduced for ferroelectric switching on partial or individual chains. It is reasonable to believe that the dipole moment flipping on specific chain can be achieved through a moderate external field, thereby providing new directions for the design of low-energy-consumption and high-density ferroelectric memory device.
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