Magnetic and thermodynamic properties of the lightly electron-doped manganite compound (Ca,Sr)Mn0.95Sb0.05O3

We report on the dc magnetization and ac magnetic susceptibility of the lightly electron-doped manganite compound (Ca1−x2+Srx2+)Mn0.94+Mn0.053+Sb0.055+O32− (x=0.0, 0.05, 0.10, 0.15, 0.16, 0.17, and 0.2) with a fixed carrier content, to examine the effect of chemical pressure on magnetization reversal of this system. In a weak magnetic-field-cooled measurement, diamagnetic magnetization is observed for x≤15%, which changes to positive values for x>15%. We present a magnetic phase diagram as a function of Sr concentration in several magnetic fields. The ac magnetic susceptibility measurement indicates the existence of magnetic frustration for the Sr substituted samples exhibiting diamagnetic behavior. To better understand the thermodynamic properties of this system, we have measured the specific heat as a function of temperature over a field cooling of 100 Oe. Our data show no anomalies associated with the temperature-dependent magnetization reversal, indicating the absence of long-range magnetic ordering.