Effect of uniaxial pressure on charge transport in the layered manganite La_(1.25)Sr_(1.75)Mn_2O_7

摘要

The effect of uniaxial pressure on resistivity along the ab plane (ρ_(ab)) and c axis (ρ_c) in single crystals of bilayer manganite La_(1.25)Sr_(1.75)Mn_2O_7 has been investigated. A prominent finding is the asymmetric role of pressure on charge transport phenomenon. With increasing pressure along the c axis, ρ_(ab) decreases and the metal-insulator (MI) transition temperature shifts towards higher temperature at the rate of 46 K/GPa. In contrary to this, ρ_c increases and the MI transition temperature decreases with increasing pressure along the ab plane. The resistivity ratio ρ_c/ρ_(ab) is quite large, increases with pressure, and shows a peak at around the MI transition. We believe that the unusual behavior of transport properties is related to the Mn-O-Mn linkage between MnO_2 layers and the spin reorientation from the c axis to the basal plane and vice versa with pressure.