Low-temperature transport properties in a bilayered manganite La1.3Sr1.7Mn2O7

Low-temperature magnetotransport properties have been investigated for a single crystal of La1.3Sr1.7Mn2O7 with a bilayered structure to reveal the ground-state nature of the quasi-two-dimensional ferromagnetic state. The specific heat measured in a magnetic field indicates a finite density of state of electrons at the Fermi level with seemingly least mass renormalization, which are subject to the weak-localization effect as evidenced by the T-1/2 dependence of the conductivity. The highly anisotropic magnetoresistance at low temperatures with respect to the field direction arises from the spin-valve effect due to the ferromagnetic-domain rotation as well as from the field destruction of the localization effect, proving a quasi-two-dimensional diffusive metal as the ground state. [S0163-1829(99)08729-9].