Magnetic-field-induced transitions and evolution of magnetotransport properties in quasi-two-dimensional KMo6O17in the charge-density-wave phase

Longitudinal magnetoresistivity ${\ensuremath{\rho}}_{xx}(B)$ and Hall resistivity ${\ensuremath{\rho}}_{xy}(B)$ of KMo${}_{6}$O${}_{17}$ single crystals have been measured up to 60 T in a pulse magnet. Remarkable and unusual features at characteristic magnetic fields were found in both ${\ensuremath{\rho}}_{xx}(B)$ and ${\ensuremath{\rho}}_{xy}(B)$, which were attributed to Fermi surface reconstructions caused by field-induced density-wave transitions. To understand these transitions in detail, we analyzed ${\ensuremath{\rho}}_{xx}(B)$ and ${\ensuremath{\rho}}_{xy}(B)$ based on a multiband model. This model successfully described the experimental results, revealing that charge carriers are increased significantly at these transitions with increasing magnetic field as a result of the Fermi surface reconstruction. In particular, the charge carriers are increased by two orders of magnitude at ${B}_{\mathrm{osc}}=\ensuremath{\sim}40$ T, above which a quantum oscillation emerges in both ${\ensuremath{\rho}}_{xx}(B)$ and ${\ensuremath{\rho}}_{xy}(B)$. This strongly suggests that the field-induced quantum oscillation is closely related with the induced charge carriers.