Consequences of embeddingTi4+3d0centers inPr0.50Ca0.50MnO3: Phase competition inPr0.50Ca0.50Mn1−xTixO3

Abstract

We have studied the structural and magnetic phase coexistence/competition derived from the partial random substitution of $3{d}^{0}$ nonmagnetic ${\text{Ti}}^{4+}$ ions for Mn in ${\text{Pr}}_{0.50}{\text{Ca}}_{0.50}{\text{MnO}}_{3}$, and their evolution with the doping level in ${\text{Pr}}_{0.50}{\text{Ca}}_{0.50}{\text{Mn}}_{1\ensuremath{-}x}{\text{Ti}}_{x}{\text{O}}_{3}$ ($x=0$, 0.01, 0.03, and 0.05) manganites. Combining high-resolution synchrotron, neutron powder-diffraction, and muon techniques we describe with great detail the coexistence of two different structural phases below $\ensuremath{\approx}240\text{ }\text{K}$ (charge-order transition temperature, ${T}_{\text{CO}}$) with different cell distortion, antiferromagnetic order, and strain characteristics. The evolution of all these features with Ti substitution level is thoroughly described. ${\text{Ti}}^{4+}$ $(3{d}^{0})$ ions do not favor the stabilization of ferromagnetic/metallic (FM/M) islands/regions in the antiferromagnetic/insulating (AFM/I) orbital-ordered matrix. The absence of short- and long-range ferromagnetism in zero field has been confirmed by different techniques. The proportion of microdomains exhibiting pseudo-(CE)-type magnetic order (CE: charge exchange) increases with the Ti content at expenses of the CE-type regions. Differences in the stability of competing phases against magnetic field have been found by neutron-diffraction measurements under application of external fields. The phase coexistence exhibits strong anisotropic strain effects that have been thoroughly analyzed as a function of the Ti content $x$. We have found very remarkable changes in the strain characteristics of the AFM segregated phases on going from 1% to 5% Ti. Large anisotropic strains develop mainly in the minority phase of the material. The magnitude of strains is discussed in comparison with anisotropic strain values recently determined in the case of substitutions (such as Co) that favor FM/M domains.