LOW-TEMPERATURE RESISTIVITY MINIMUM IN CERAMICAL AND SINGLE-CRYSTALLINE PEROVSKITE MANGANITES: INTERGRAIN TUNNELING VERSUS BULK COULOMB INTERACTION EFFECT

摘要

The interest in the manganite perovskites R_(1-x)A_zMnO_3, where R is a trivalent rare-earth (e.g. La) and A is a divalent (e.g. alkali-earth) ions, was revived during the last decade. It was generated by potential applications arising from large magneto-resistance (MR) in these materials. Although the viability of such applications remains an open issue, this interest is maintained as these materials exhibit rich interplay between charge, spin and lattice derived effects.