Colossal Magnetoresistance of A-Site Ordered (NdBaSm)2Mn2O6 at Ambient Temperature

概要

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The behavior of the A-site ordered (Nd(1-L)PrL)(1-x)Ba(1-y)Sm(x+y)Mn2O6 shows remarkable dependence on $y$. Whereas the effect of the increase in $x$ and $L$ is understandable using the phase diagram, the change with $y$ shows anomalous behavior. Charge and orbital (CO) ordering is absent in the host NdBaMn2O6, appears with $x$, increases with $y$ initially but disappears when $y$ becomes greater than 0.1. The magnetoresistance (MR) at room temperature is maximum for a composition that shows high CO ordering temperature. Such a composition provides MR at room temperature, which is an order of magnitude larger than the value obtained in earlier studies. In the absence of CO ordering for $y\geq 0.1$, MR is maximum when the composition is close to the phase boundary separating it from the metallic phase, although the maximum MR occurs at a lower temperature. Nevertheless, a room-temperature MR of 700% has been obtained in this case also. The phenomenon of the cusp-like increase in MR at the metal-insulator phase boundary is explained and experimental support is obtained.
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2008-10-25