Monocrystalline SrMnBi2 thin films were grown by molecular beam epitaxy （MBE）, and their transport properties were investigated. A high and unsaturated linear magnetoresistance （MR） was observed, which exhibited a...Monocrystalline SrMnBi2 thin films were grown by molecular beam epitaxy （MBE）, and their transport properties were investigated. A high and unsaturated linear magnetoresistance （MR） was observed, which exhibited a transition from a semi-classical weak-field B2 dependence to a high-field linear dependence. An unusual nonlinear Hall resistance was also observed because of the anisotropic Dirac fermions. The two-carrier model was adopted to analyze the unusual Hall resistance quantitatively. The fitting results yielded carrier densities and mobilities of 3.75×10^14 cm^-2 and 850 cm^2·V^-1·s^-1, respectively, for holes, and 1.468×10^13 cm^-2, 4118 cm^2·V^-1·s^-1, respectively, for electrons, with a hole-dominant conduction at 2.5 K. Hence, an effective mobility can be achieved, which is in reasonable agreement with the effective hole mobility of 1800 cm^2·V^-1·s^-1, extracted from the MR. Further, the angle-dependent MR, proportional to cos 0, where 0 is the angle between the external magnetic field and the perpendicular orientation of the sample plane, also implies a high anisotropy of the Fermi surface. Our results about SrMnBi2 thin films, as one of a new class of AEMnBi2 and AEMnSb2 （AE = Ca, Sr, Ba, Yb, Eu） materials, suggest that they have a lot of exotic transport properties to be investigated, and that their high mobility might facilitate electronic device applications.展开更多
文摘Monocrystalline SrMnBi2 thin films were grown by molecular beam epitaxy （MBE）, and their transport properties were investigated. A high and unsaturated linear magnetoresistance （MR） was observed, which exhibited a transition from a semi-classical weak-field B2 dependence to a high-field linear dependence. An unusual nonlinear Hall resistance was also observed because of the anisotropic Dirac fermions. The two-carrier model was adopted to analyze the unusual Hall resistance quantitatively. The fitting results yielded carrier densities and mobilities of 3.75×10^14 cm^-2 and 850 cm^2·V^-1·s^-1, respectively, for holes, and 1.468×10^13 cm^-2, 4118 cm^2·V^-1·s^-1, respectively, for electrons, with a hole-dominant conduction at 2.5 K. Hence, an effective mobility can be achieved, which is in reasonable agreement with the effective hole mobility of 1800 cm^2·V^-1·s^-1, extracted from the MR. Further, the angle-dependent MR, proportional to cos 0, where 0 is the angle between the external magnetic field and the perpendicular orientation of the sample plane, also implies a high anisotropy of the Fermi surface. Our results about SrMnBi2 thin films, as one of a new class of AEMnBi2 and AEMnSb2 （AE = Ca, Sr, Ba, Yb, Eu） materials, suggest that they have a lot of exotic transport properties to be investigated, and that their high mobility might facilitate electronic device applications.
