Low Temperature Magnetoresistance and the Magnetic Phase Diagram ofLa1−xCaxMnO3

Abstract

The complete phase diagram of a “colossal” magnetoresistance material ( ${\mathrm{La}}_{1-x}{\mathrm{Ca}}_x{\mathrm{MnO}}_3$) was obtained for the first time through magnetization and resistivity measurements over a broad range of temperatures and concentrations. Near $x=0.50\mathrm{}$, the ground state changes from a ferromagnetic (FM) conductor to an antiferromagnetic (AFM) insulator, leading to a strongly first order AFM transition with supercooling of $\sim 30\%$ $T_N$ at $x=0.50\mathrm{}$. An unexpectedly large magnetoresistance is seen at low temperatures in the FM phase, and is largely attributed to unusual domain wall scattering.