Magnetization Study of the AFM-FM Coexistence in the Manganite System Pr_0.5Ca_0.5-xSr_xMnO₃

Abstract

For the manganites Pr 0.5 Ca 0.5−x Sr x MnO 3 (x = 0; 0.3) the temperature and cooling field dependence of the reduced remanence asymmetry indicates the antiferromagnetic exchange between the antiferromagnetic and ferromagnetic spins at the surface of the clusters. For x = 0.3 we deduce the radius of the cluster in the field cooled regime to be about 20 times larger than that for x = 0. General informationThe manganite perovskites Pr 0.5 Ca 0.5−x Sr x MnO 3 were studied with the aim to investigate magnetic and structural phase transitions as well as the phase separation into the antiferromagnetic (AFM) and ferromagnetic (FM) regions [1,2]. The neutron diffraction, NMR and magnetometric studies were performed to determine the phase diagram of the system and the relative volumes of the magnetic phases. In the temperature region below about 170 K, these materials represent antiferromagnets containing a small portion (< 10 percents) of the minor ferromagnetic phase. The present contribution follows the works mentioned above and brings new results based on measurements of the exchange bias (EB) [3]. This method, which can yield information on the interface exchange interaction between the phases has been recently applied to a charge ordered manganite Pr 1/3 Ca 2/3 MnO 3 [4]. We focus our attention on the compositions x = 0 and 0.3 representing a small and medium content of the FM phase, respectively. ExperimentalThe ceramic materials used in the experiments were the same as those described in the work [1]. The samples contained a small volume of Mn 3 O 4 hav- (143)

The low-temperature magnetostructure and magnetic field response of Pr0.9Ca0.1MnO3: the roles of Pr spins and magnetic phase separation

“…The predominant magnetic character (FM or AFM) of each peak is also indicated, although many peaks like (1 1 1) actually have both FM and AFM intensity contributions based on the underlying magnetostructural symmetry conditions. Note how the increased background cancels the temperature dependence of the FM (0 2 0) reflection at µ = H 0.0 0 T. A very small amount of Mn 3 O 4 , a typical ferrimagnetic impurity phase in manganites [38][39][40][41] with a Néel transition at ≈ T 45 N K [42], can be observed in the 5 K diffractograms due to the considerably low noise level (high counting time). No other signs of complications from this impurity were met during the course of the present work.…”