  Intriguing novel phenomena in lead films inspire new understanding of quantum
physics, such as quantum size effect and quantum phase transitions etc. The
improvement of the sample quality makes it even more promising to explore the
intrinsic properties in two-dimensional system. In this paper, we show that the
crystalline interfacial striped incommensurate layer can increase the quality
of the lead films and significantly enhance the magnitude of magnetoresistance.
By performing systematic transport measurement, a predominant anomalous linear
magnetoresistance is revealed, and the widely used Parish-Littlewood model and
Abrikosov's explanation fail to describe the observation. Instead, we propose a
new model of linear magnetoresistance based on linear band structure, which
shows a good agreement with the experimental results. Our studies reveal a
novel origin of linear magnetoresistance which may also be helpful to
understand the linear magnetoresistance in other materials with linear
dispersion of electronic structure.
