A Ferrimagnetic Manganese Oxide with a Layered Perovskite Structure: YBaMn_2O_5

摘要

There is renewed interest in perovskite-type Ln_(1-x)A_xMnO_3 phases (Ln = trivalent lanthanide; A = Ca. Sr, or Ba). following the discovery of giant negative magnetoresistances (GMR) at the transition between their conducting ferromagnetic and insulating paramagnetic states. GMR has been found in both thin film and sintered polycrystalline samples with x approx = 0.3, and anisotropic GMR phenomena have recently been reported in layered Ruddlesden- Popper type perovskites (Ln,A)_(n+1) Mn_n O_(3n+1)for n = 2. Similar effects have also been observed in the oxyeen-deficient. cubic pyrochlore Tl_2Mn_2O_(7-δ).