Magnetic Inhomogeneity and Magnetotransport in Electron-Doped Ca(1-x)La(x)MnO(3) (0<=x<=0.10)

TL;DR

This study investigates how magnetic inhomogeneity affects magnetotransport in lightly electron-doped Ca(1-x)La(x)MnO(3), revealing a crossover to a spin-canted phase and a magnetoresistance behavior similar to colossal magnetoresistance materials but with much smaller magnitude.

Contribution

It provides detailed insights into the magnetic crossover near x=0.02 and links magnetotransport properties to magnetic inhomogeneity in electron-doped manganites.

Findings

Magnetoresistance follows a -C(M/M_S)^2 dependence in the paramagnetic phase.

The parameter C is two orders of magnitude smaller than in CMR materials.

Electronic inhomogeneity persists well above the magnetic transition temperature.

Abstract

The dc magnetization (M) and electrical resistivity (\rho) as functions of magnetic field and temperature are reported for a series of lightly electron dopedCa(1-x)La(x)MnO(3) (0<=x<=0.10) specimens for which magnetization [Phys. Rev. B {\bf 61}, 14319 (2000)] and scattering studies [Phys. Rev. B {\bf 68}, 134440 (2003)] indicate an inhomogeneous magnetic ground state composed of ferromagnetic (FM) droplets embedded in a G-type antiferromagnetic matrix. A change in the magnetic behavior near x=0.02 has been suggested to be the signature of a crossover to a long-ranged spin-canted phase. The data reported here provide further detail about this crossover in the magnetization, and additional insight into the origin of this phenomenon through its manifestation in the magnetotransport. In the paramagnetic phase (T>=125 K) we find a magnetoresistance =-C(M/M_S)^2 (M_S is the low-T saturation magnetization), as observed in many manganites in the ferromagnetic (FM), colossal magnetoresistance (CMR) region of the phase diagram, but with a value of C that is two orders of magnitude smaller than observed for CMR materials. The doping behavior C(x) follows that of M_S(x), indicating that electronic inhomogeneity associated with FM fluctuations occurs well above the magnetic ordering transition.