High electron mobility and transverse negative magnetoresistance in van der Waals material Nb2GeTe4

摘要

Two-dimensional(2D)semiconductors with high charge-carrier mobility and exotic quantum properties are of great importance for the design of outstanding electronic devices.Here we report the single crystal growth of van der Waals material Nb2GeTe4,which exhibits very high mobility and unusual transverse negative magnetoresistance(MR)from our transport-property-measurements.Nb2GeTe4 adopts a Te-Nb(Ge)-Te sandwiched layer structure and exhibits a narrow-gap semiconducting behavior.Based on ultraviolet-visible-near infrared(UV-vis-NIR)optical measurement,the optical band gap of Nb2GeTe4 is determined to be around 0.39 eV.The high electron mobility of the Nb2GeTe4 bulk crystal at room temperature,424.37 cm~2 V~(-1)s~(-1),is comparable to those of the current state-of-the-art high-mobility layered materials,making Nb2GeTe4 competitive for the design of 2D electronic devices.An anomalous negative magnetoresistance is also observed in Nb2GeTe4 below 10 K with different field dependency,where the maximum MR reaches B31% at 5 K and 5 T.