Synthesis, structural, electrical and magnetic studies of La0.5Ca0.45−xSrxBa0.05MnO3

Electronic transport and magnetoresistivity of La0.4Bi0.1Ca0.5−x Sr x MnO3 (x = 0.1 and 0.2)

“…The lattice parameters are estimated using XRDA software with a maximum error of ± 0.009 Å (table 1). 26,27 The unit cell volume is observed to increase with the increase of x consistent with the fact that relatively bigger Sr 2+ ions are substituted for Ca 2+ ions. 19 The average crystallite size (d), as given in table 1, estimated using the Scherrer formula is found to be in the nanorange for both the compounds.…”

“…The electronic transport properties particularly in the paramagnetic phase of manganites are usually explained using different transport mechanisms: (i) a simple activation (SA) law, ρ = ρ 0 exp(E a /k B T), where E a is the activation energy, (ii) adiabatic small polaron model (ASP), having its origin from the local lattice distortion accompanying the moving charge carrier (Jahn-Teller polaron) ρ = AT exp(E a /k B T), and the variable range hopping (VRH) model [ρ = ρ ∞ [exp(T 0 /T) 1/4 ]], where ρ ∞ is the residual resistivity with the localization of charge carriers by the magnetic disorder, 26 where T 0 is the characteristic temperature. Accordingly, the resistivity behaviour of the present samples is investigated using the above models to determine the most probable mechanism of conduction in the high-temperature domain.…”

“…26,34,35 In this connection, various models involving the collective action of several different mechanisms are proposed to explain this lowtemperature phenomenon. 26,[36][37][38][39] Attempt to fit the resistivity data of x = 0.1 sample with the model ρ (T) = ab ln T + cT 1/2 + dT 2 is found to be successful ( figure 4). Apart from the usual Coulomb scattering term (dT 2 ), Kondo-like scattering (b ln T) and correlated electronelectron interaction (cT 1/2 ) in weakly disordered system 40 figure in this model.…”

Synthesis and characterization of La 0.75 Ca 0.15 Sr 0.05 Ba 0.05 MnO 3 –Ni 0.9 Zn 0.1 Fe 2 O 4 multiferroic composites

“…The doping at A site (the divalent alkali-earth metal ions) of these manganites can both lead to the appearance of Mn 4 þ ions which produces Mn 3 þ -O-Mn 4 þ double-exchange function [45] and change the average radius of A-site ions to adjust the bond length and bond angle of ABO 3 oxygen octahedrons and to influence double-exchange function [46,47]. We have selected La 0.75 Ca 0.15 Sr 0.05 Ba 0.05 MnO 3 (LCSBMO) as the matrix which is a mixture of La 0.7 Ca 0.3 MnO 3 , LSMO, and La 0.7 Ba 0.3 MnO 3 , respectively because light doping of Sr 2 þ and Ba 2 þ for Ca 2 þ ions caused a shift of paramagnetic (PM) to ferromagnetic (FM) transition temperature (T c ) to a higher value close to room temperature as well as improves the electrical and magetotransport properties [48][49][50]. On the other hand, the simultaneous of Sr-Ba results in a Mn 3 þ /Mn 4 þ mixed valence state creating mobile charge carriers and canting of Mn spins [51].…”

Electrical and magneto transport properties of La0.8−x Ca x Sr0.1Ag0.1MnO3 (x = 0.1, 0.2, 0.3)

“…where ρ ∞ is the temperature-independent parameter and T o the characteristic temperature [32]. The fitting of resistivity data with VRH model is also shown in figure 5a-c and the estimated values of ρ ∞ and T o values are shown in table 2.…”