Electron Transport Properties In Transition Metal Dichalcogenides NbTe2

NbTe₂is a typical layered quasi-two-dimensional transition metal dichalcogenide with a 1T’-type structure.A non-saturating linear magnetoresistance was observed in single crystals of the NbTe₂due to the distorted crystal structure.Recently,an unsaturated linear magnetoresistance（MR）has been explained as the Abrikosov quantum MR caused by small Fermi pockets with linear dispersion.However,we suppose that the explanations given in the current experimental research are not self-consistent with the experimental results.In our opinion,it is necessary to further explore the source of the non-saturating linear magnetoresistance in NbTe₂based on the previous experiment,and to conclude a reasonable and self-consistent explanation.In this thesis,we present the low-temperature electron transport data obtained in two devices based on NbTe₂,labelled as Device 1 and Device 2.Similar unsaturated linear MR was observed in both devices at high magnetic fields.However,a careful analysis of the experimental data reveals that the observed linear MR is not consistent with the Abrikosov quantum linear MR model.On the other hand,it is found that all the MR curves are well fitted with the effective-medium model which describes the classical MR of an inhomogeneous conductor,indicating that the linear MR in NbTe₂is most likely due to the spatial fluctuation of carrier concentration and mobility caused by the inhomogeneity of the sample;Meanwhile,the abundant domain structures observed in NbTe₂crystals by transmission electron microscope measurements also support this speculation.