Robustness of frictional anisotropy under high load due to self-folding

Abstract

Friction anisotropy is not only related to macroscopic natural phenomena, but also closely involves the emerging field of nanotechnology. The previous strategies to achieve friction anisotropy requires delicate adjustment, which is difficult to achieve in method, or easy to disappear under large loads. Here, we report the outstanding robustness of frictional anisotropy caused by its own fold structure under high load. The frictional anisotropy is always larger than 200% between the armchair and zigzag direction of Se/Se interface under load up to 5.5 GPa and its maximum value reaches 325%. The frictional anisotropy between these two directions origins from the tremendous difference in charge density redistribution reflected only in direction perpendicular to interface, which is a novel method to quantitatively characterize friction from the perspective of electronic interaction. The load-induced weakening of friction anisotropy derives from the sudden change in chemical interactions between atoms around interface. The exploring of extreme frictional anisotropy caused by its own structure is not only helpful for a comprehensive understanding of frictional anisotropy behavior, but also contributes to the construction of nanodevices required the friction anisotropy to achieve, such as mechanical logic gates.