Compton profile of VO2 across the metal-insulator transition: Evidence of a non-Fermi liquid metal

Many-body diffusion Monte Carlo is used to obtain the first-principles momentum distribution and Compton profile of vanadium dioxide. Our results for the Compton profile are in good agreement with the experimental values, and we show that good qualitative agreement in the scaled Compton profile difference across the monoclinic to rutile phase transition depends on an accurate description of electron correlation. The electron momentum distribution enables new insights into the metal-insulator phase transition. For example, the probability for electron scattering in the proximity of the Fermi surface (forward scattering) is suppressed in the vanadium chain direction (rutile c axis) but enhanced in perpendicular directions. However, along the c axis we observe an increase at ∼2kF in the momentum distribution, which is characteristic for Friedel oscillations (backscattering). Our analysis of the momentum distribution supports experimentally observed anisotropies and provides an explanation for the anomalously low electronic thermal conductivity observed recently in the metallic phase [S. Lee, Science 355, 371 (2017)10.1126/science.aag0410]. Moreover, our results indicate non-Fermi liquid behavior as well as quasi-one-dimensional Friedel oscillations in the metallic rutile phase, which is reminiscent of a Tomanaga-Luttinger liquid with impurities.