Study of structural, transport and magneto-crystalline anisotropy in La1−xSrxMnO3 (0.30 ≤ x ≤ 0.40) perovskite manganites

Abstract

In this paper we present structural, transport, magnetic and magneto-crystalline anisotropy of La1−xSrxMnO3 (х = 0.30, 0.33, 0.36, and 0.40) synthesized using the solid-state reaction method. The X-ray diffraction pattern of the samples is well indexed to the rhombohedral structure with R3̄c space group. Lattice parameters and unit cell volume are found to decrease monotonically upon increasing Sr2+ concentration at La3+ site. X-ray photoelectron spectroscopy confirms the presence of Mn4+ and Mn3+, the ratio of which (Mn4+/Mn3+) increases from 0.44 to 0.64 with increasing Sr2+ concentration. From the ρ(T) and M(T) data analysis, we find that TMI and MS are larger for x = 0.33 composition, suggesting a weakening of the double-exchange interaction due to competing super-exchange interactions in x = 0.30, 0.36 and 0.40 samples. We calculated MCA constant (K1) by fitting the saturation magnetisation data at a higher magnetic field using the law of approach model, M = MS [1-a/H-b/H2]-χH with K12 = (105/8)bMs2 and is in the order of 105 erg/cm3.

Mechanochemical Synthesis of Soft Ferromagnetic Perovskite Lanthanum Strontium Manganite (La0.6Sr0.4MnO3)

“…On the other hand, the saturation magnetization obtained from our results is much lower for the value published for bulk La 0.6 Sr 0.4 MnO 3 sample 15,37,45 for which the saturation magnetization at 300 K is expected to be about 2-2.5 μ B /f.u. and 3.6-3.9 μ B /f.u.…”

“…The obtained values of room temperature resistivity and magnetoresistance are in accepted agreement with previously published data for perovskite phase, with close compositions. The value of MR for nanogranular manganite compounds is expected, as was shown in previously published data, 11,45,48 to increase with the decrease of temperature, which makes the La 0.6 Sr 0.4 MnO 3 sample (prepared in the present work) a good candidate for practical applications related to the magneto-conduction.…”

“…The high field region of the hysteresis loops was fitted by the law of approach to saturation. 43,45…”

“…The intensity of the ferromagnetic double exchange interaction is very sensitive to the Mn 4+ /Mn 3+ ratio and was found to be maximum when this ratio is about 0.33. 45 Any deviation in this ratio will change the intensity of these two exchange interactions in competition (the double exchange and the super exchange), which in turn will affect the saturated value of magnetic moment per formula unit.…”

Double-doping Effect on Structural and Magnetic Properties of Perovskite Lanthanum Manganite

“…Consequently, the appearance of ferromagnetic behavior in the x = 0 sample (La 0.67 Sr 0.333 MnO 3 ) is in good agreement with the published phase diagram. 30 The curie temperature of the bulk La 0.67 Sr 0.333 MnO 3 sample, as was published previously, 13,30,31 is about 375 K. It can be noted that, the value of saturation magnetization (magnetization at maximum applied field) Table I. The lattice parameters (a) and (c), the volume (V) of the unit cell and the crystallite size (d) for La (2+4x)/3 Sr (1-4x)/3 Mn 1−x Cu x O 3 samples (x = 0.0, 0.1, 0.15 and 0.25).…”