Electrical properties of fluorine-intercalated layered manganite: La1.4Sr1.6Mn2O7F2

Abstract

Fluorinating agent NH4F is employed to intercalate the bi-layered manganite La1.4Sr1.6Mn2O7 to form La1.4Sr1.6Mn2O7F2 using solid state reaction. The insertion of fluorine results in a contraction of ∼0.116Å in the a axis and an expansion of ∼3.152Å in the c axis with respect to the parent compound La1.4Sr1.6Mn2O7. The Mn–O bond lengths are altered due to the electrostatic repulsion between O2− and F−. Rietveld analysis indicates that a longer bond length of Mn–O(1) and shorter bond lengths of Mn–O(2) and Mn–O(3) has been found in La1.4Sr1.6Mn2O7F2 when compared to La1.4Sr1.6Mn2O7. The electrical resistivity of La1.4Sr1.6Mn2O7F2 shows insulating behavior and exhibits remarkably different behavior from La1.4Sr1.6Mn2O7. For the first time, we report the temperature dependence of electrical resistivity of La1.4Sr1.6Mn2O7F2. Magnetic measurements indicate that the magnetic order of local moments is suppressed by fluorine insertion into interstitial sites.