Phase separation and segregation in rare earth manganates: the experimental situation

Inhomogeneous magnetic behavior of Pr0.7Ca0.3CoO3 and Nd0.7Ca0.3CoO3

“…Thus, while La 0.7 Ca 0.3 MnO 3 (<r A > = 1.205 Å) shows insulator to metal transition and ferromagnetism, with metallicity associated with ferromagnetism at low temperatures [3,4,8], Pr 0.7 Ca 0.3 MnO 3 with a smaller <r A > (1.179 Å) shows no ferromagnetism or insulator to metal transition. Instead, the latter manganate exhibits charge ordering, orbital ordering and electronic phase separation [3,4,9]. We were interested in exploring whether the analogous cobaltates of general formula Ln 1-x A x CoO 3 (Ln = rare earth, A = alkaline earth) exhibit similar features.…”

“…Investigations of rare earth manganates of the general formula Ln 1-x A x MnO 3 (Ln = rare earth, A = alkaline earth) have revealed remarkable aspects of these materials which include colossal magnetoresistance (CMR), charge ordering (CO), orbital ordering as well as electronic phase separation [1][2][3][4]. Properties of these materials are crucially controlled by the average radius of the A-site cation, <r A > [3][4][5][6][7].…”

“…Properties of these materials are crucially controlled by the average radius of the A-site cation, <r A > [3][4][5][6][7]. Thus, while La 0.7 Ca 0.3 MnO 3 (<r A > = 1.205 Å) shows insulator to metal transition and ferromagnetism, with metallicity associated with ferromagnetism at low temperatures [3,4,8], Pr 0.7 Ca 0.3 MnO 3 with a smaller <r A > (1.179 Å) shows no ferromagnetism or insulator to metal transition. Instead, the latter manganate exhibits charge ordering, orbital ordering and electronic phase separation [3,4,9].…”

Magnetic and electron transport properties of the rare earth cobaltates, La0.7 xLnxCa0.3CoO3(Ln = Pr, Nd, Gd and Dy): a case of phase separation

“…Rare-earth manganates of the general formula Ln 1-x A x MnO 3 (Ln = rare earth, A = alkaline earth), possessing the perovskite structure, exhibit interesting properties such as colossal magnetoresistance, charge ordering and electronic phase separation [1][2][3][4][5]. These properties of the manganates are strongly influenced by the average radius of the A-site cations, <r A >.…”

Limited local electron-lattice coupling in manganites: An electron diffraction study

“…Subsequently, our experimental findings were found to be reasonable in theoretical models where modulated phases are stabilized with small and even zero electron-lattice coupling. 13,20 However, one anticipates that our evidence 18,19 against strong coupling in ͑La, Ca͒MnO 3 would not extend to a supposedly strong 1,7,[9][10][11][12] 3 , and then it was twice reground, repelleted, and heated at 1350°C for 4 days. X-ray powder diffraction in a Philips PW1050 diffractometer ͑Cu K␣͒ recorded only a single phase, and we infer that at least the grains of interest are chemically homogeneous given that we observe q / a * to be highly homogeneous.…”