Phase coexistence in manganites: doping and structural dependence

G. ALEJANDRO; M. OTERO-LEAL; M. GRANADA; D. LAURA-CCAHUANA; M. TOVAR; E. WINKLER; M. T. CAUSA

JOURNAL OF PHYSICS CONDENSED MATTER

IOP PUBLISHING LTD

Año: 2010 vol. 22 p. 256002 - 256002

0953-8984

We present a study on the phase coexistence (PC) of paramagnetic insulating (PMI) and ferromagnetic metallic (FM-M) phases in the La1-y(Ca1-xSrx)yMnO3 system with y between 0.23 and 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 TC, a FM asymmetric line is observed shifted to low fields. In a DT temperature range both lines are visible, defining a range of PC. For x = 0, we obtained DT as a function of the carrier concentration y, finding that the largest DT corresponds to y = 0.25. For this y value, the extreme compounds are orthorhombic and rhombohedral for x = 0 and x = 1, respectively. The rhombohedral to orthorhombic temperature transition (TRO) was determined as a function of x. We found that DT is different from 0 only if TC is lower than TRO. The PM- I/FM-M phase coexistence was only observed in the orthorhombic phase while seems to be non-compatible with the more symmetric rhombohedral phase.