Alejandro G, Otero-Leal M, Granada M, Laura-Ccahuana D, Tovar M, Winkler E, Causa MT. Phase coexistence in manganites: doping and structural dependence.
JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010;
22:256002. [PMID:
21393810 DOI:
10.1088/0953-8984/22/25/256002]
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Abstract
We present a study on the phase coexistence (PC) of paramagnetic insulating (PM-I) and ferromagnetic metallic (FM-M) phases in the La(1- y)(Ca(1-x)Sr(x))(y)MnO(3) system with 0.23 ≤ y ≤ 0.45. The study was performed by means of magnetization and electron spin resonance (ESR) measurements. At high temperatures the ESR spectrum consists of a single symmetric PM line. At T(C), a FM asymmetric line is observed shifted to low fields. In a ΔT temperature range both lines are visible, defining a range of PC. For x = 0, we obtained ΔT as a function of the carrier concentration y, finding that the largest ΔT corresponds to y = 0.25. For this y value, the extreme compounds are orthorhombic and rhombohedral for x = 0 and 1, respectively. The rhombohedral to orthorhombic temperature transition (T(RO)) was determined as a function of x. We found that [Formula: see text] only if T(C) < T(RO). The PM-I/FM-M phase coexistence was only observed in the orthorhombic phase while seems to be incompatible with the more symmetric rhombohedral phase.
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