Structural and magnetic properties in the self-doped perovskite manganites with nominal composition La0.7Sr0.3−xMnO3−δ

Monte Carlo Calculations of Magnetic Heat Capacity of La0.7Sr0.3-x MnO3-d

“…The magnetic heat capacity was calculated using (4). According to the experimental data [24] and present theoretical calculations, the magnetization and the magnetic ordering temperature in the doped La 0.7 Sr 0.3−x MnO 3−δ decreased with increasing x. This may be a result of the fact that Mn-O bond lengths increase with increasing x [24].…”

“…2 that the sample with x = 0.10 possesses the smallest amplitude of magnetic heat capacity peak. This may be a result of the fact that this sample possesses the minimum volume averaged crystallite diameter [24] and consequently the largest number of surface ions relative to the total number anions in the crystallites. The magnetic ordered temperature of the ions in the surface layer is lower than for those in the core.…”

Magnetic Properties of Mixed Valence La(AgSr)MnO3 Manganites Obtained by Solid‐State Reaction Method

“…Lanthanum–manganese‐based perovskites, also known as “manganites”, with mixed valence substitutions described by the formula La 1− x A x MnO 3 (where A can be a divalent metal like Ca, Ba, or Sr or a monovalent cation like Ag, Na, or K) have been a subject of intense research due to their interesting electronic properties, which include a variety of phenomena like colossal magnetoresistance, charge ordering, isotopic effect, phase separation, and magnetocaloric effect, together with multiple possible magnetic states, such as canted antiferromagnetic, paramagnetic isolator, ferromagnetic isolator, ferromagnetic metallic, and antiferromagnetic . In particular, divalent substitution represented by partial La 3+ replacement by Sr 2+ have shown to be effective for tailoring magnetic properties such as the saturation magnetization M s and Curie temperature T c . Large variations as large as Δ T c = 200 K have been reported for Sr contents x between 0.1 and 0.50 for La 1− x Sr x MnO 3 series together with intermediate M s values (around 35 Am 2 /kg, compared with La 1− x Ca x systems with high M s around 50 Am 2 /kg) for Sr concentration lower than x = 0.30 at room temperature .…”

“…In particular, divalent substitution represented by partial La 3+ replacement by Sr 2+ have shown to be effective for tailoring magnetic properties such as the saturation magnetization M s and Curie temperature T c . Large variations as large as Δ T c = 200 K have been reported for Sr contents x between 0.1 and 0.50 for La 1− x Sr x MnO 3 series together with intermediate M s values (around 35 Am 2 /kg, compared with La 1− x Ca x systems with high M s around 50 Am 2 /kg) for Sr concentration lower than x = 0.30 at room temperature . This marked dependence of the magnetic response with the Sr concentration has been explained in terms of the influence of the divalent atoms affecting the superexchange mechanism in favor of the double exchange interaction, which leads to higher T c and M s .…”

“…This marked dependence of the magnetic response with the Sr concentration has been explained in terms of the influence of the divalent atoms affecting the superexchange mechanism in favor of the double exchange interaction, which leads to higher T c and M s . In addition, the crystal structural deformation caused by the incorporation of large Sr atoms (with respect to O and Mn ions) significantly influences the charge‐carrier band structure and hence, the electronic properties of these materials . For instance, a change in order–disorder magnetic transition type (from first to second order) has been described as a result of the increasing Sr concentration in La 2/3 (Ca 1− x Sr x ) 1/3 MnO 3 polycrystalline manganites .…”