  Anisotropic magnetoresistance (AMR) has a crucial feature for developing
highly sensitive sensors and innovative memory devices. While extensively
studied in bulk materials, AMR effects in these materials are typically weak.
Recent advancements indicate that two-dimensional (2D) van der Waals magnetic
materials possess unique magnetic properties, potentially including significant
AMR characteristics. In this study, we utilize density functional theory and
the Boltzmann transport equation to investigate AMR in magnetic monolayers
CrPX3 (X = S, Se, Te). Our findings reveal a substantially large AMR in these
2D magnetic compounds. This enhancement is attributed to magnetization
(M)-dependent spin-orbit coupling (SOC), arising from the broken symmetry
between in-plane and out-of-plane orientations. This results in significant
M-dependent band splitting and subsequent variations in electron velocity.
Additionally, we find that the M-dependent SOC is significantly enhanced by
increasing the atomic number of the chalcogen X in CrPX3, achieving an
exceptional 150% AMR in CrPTe3. Furthermore, our study demonstrates that AMR
can be effectively modulated by applying biaxial strain, resulting in a twofold
increase with a 4% strain. These findings propose a novel approach to enhancing
2D-based AMR spintronic devices, making a substantial contribution to the
field.
