Magnetic versus orbital polarons in colossal magnetoresistance manganites

Abstract

In order to investigate the paramagnetic ground state of the colossal magnetoresistance (CMR) ${\mathrm{Sm}}_{0.55}{\mathrm{Sr}}_{0.45}{\mathrm{MnO}}_{3}$ compound we have used a wide set of techniques: magnetoresistance, magnetization, high-resolution neutron diffraction, small-angle neutron diffraction, and muon spin relaxation. According to these measurements the paramagnetic ground state would consist of \ensuremath{\sim}0.8 nm ferromagnetic clusters embedded in a short-range charge/orbital ordered matrix. The CMR effect occurs due to percolation of these ferromagnetic clusters.