Low-temperature electrical transport in bilayer manganite La$_{1.2}$Sr$_{1.8}$Mn$_{2}$O$_{7}$

C. L. Zhang; X. J. Chen; C. C. Almasan; J. S. Gardner; J. L. Sarrao

doi:10.1103/PhysRevB.65.134439

paper

Low-temperature electrical transport in bilayer manganite La $_{1.2}$ Sr $_{1.8}$ Mn $_{2}$ O $_{7}$

arXiv:cond-mat/0203197 · doi:10.1103/PhysRevB.65.134439

Abstract

The temperature $T$ and magnetic field $H$ dependence of anisotropic in-plane $ρ_{ab}$ and out-of-plane $ρ_{c}$ resistivities have been investigated in single crystals of the bilayer manganite La $_{1.2}$ Sr $_{1.8}$ Mn $_{2}$ O $_{7}$ . Below the Curie transition temperature $T_{c} =$ 125 K, $ρ_{ab}$ and $ρ_{c}$ display almost the same temperature dependence with an up-turn around 50 K. In the metallic regime (50 K $\leq T \leq$ 110 K), both $ρ_{ab} (T)$ and $ρ_{c} (T)$ follow a $T^{9/2}$ dependence, consistent with the two-magnon scattering. We found that the value of the proportionality coefficient $B_{ab}^{f i t}$ and the ratio of the exchange interaction $J_{ab} / J_{c}$ obtained by fitting the data are in excellent agreement with the calculated $B_{ab}$ based on the two-magnon model and $J_{ab} / J_{c}$ deduced from neutron scattering, respectively. This provides further support for this scattering mechanism. At even lower $T$ , in the non-metallic regime ( $T <$ 50 K), {\it both} the in-plane $σ_{ab}$ and out-of-plane $σ_{c}$ conductivities obey a $T^{1/2}$ dependence, consistent with weak localization effects. Hence, this demonstrates the three-dimensional metallic nature of the bilayer manganite La $_{1.2}$ Sr $_{1.8}$ Mn $_{2}$ O $_{7}$ at $T < T_{c}$ .

7 pages and 5 figures, accepted for publication in Phys. Rev. B

Low-temperature electrical transport in bilayer manganite La1.2​Sr1.8​Mn2​O7​

Abstract

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Low-temperature electrical transport in bilayer manganite La $_{1.2}$ Sr $_{1.8}$ Mn $_{2}$ O $_{7}$