Non-percolating small metallic clusters and sharp suppression of metallicity in RE_0.55Sr_0.45Mn_1−xRu_xO₃manganites

Abstract

The origin of the anomalous sharp phase transition from a ferromagnetic metal into a ferromagnetic insulator has been investigated in ruthenium (Ru)-doped RESrMnRuO (0 ≤ x ≤ 0.25) manganites (RESRMO) with RE(A-site) = Sm, Eu and Gd. The transition is independent of RE and occurs at a Ru doping level x of around 0.16-0.18. The analysis of the temperature derivative of the resistivity and the magneto-resistance at high temperatures as a function of x suggests that the suppression of metallicity originates from the doping driven magnetic/spin disorder that coexist within the ferromagnetic metallic/insulating matrix in these compounds.

Resistive Avalanches in La1–xSrxCoO3−δ (x = 0, 0.3) Thin Films and Their Reversible Evolution by Tuning Lattice Oxygen Vacancies (δ)

“…Plateaus of the same curve observed at relatively low temperature correspond to the thermally activated conduction mechanism with a well-defined activation energy constant over a range. 50 The temperature at which the resistivity displays the point of inflections 51 is shown in Figure 8a, and the minimum is marked by the T n *, while the maximum is marked by the T n $ (n = 1, 2, 3, and 4) for the nth measurement cycle. For the vacuum measurement of the asdeposited film, i.e., n = 1 the temperature difference between the maximum and minimum is large.…”