Effects of A-site disorder on magnetic, electrical and thermal properties of La0.5−Ln Ca0.5−Sr MnO3manganites

Influence of Ce doping on electrical and thermal properties of La0.7−xCexCa0.3MnO3 (0.0≤x≤0.7) manganites

“…2(b) and (c)), indicating the occurrence of another magnetic transition to the AFM in these samples. The drop in magnetic moment could be due to the antiferromagnetic response from the rare earth element Ce or the short-range ordering of Mn 3 þ and Mn 4 þ , which leads to the charge ordered AFM state [25]. It can be seen from the Table 1 that the T C decreases monotonically with increasing Ce-doping level.…”

Electron paramagnetic resonance study of (La0.33Sm0.67)0.67Sr0.33−Ba MnO3 (x<0.1): Griffiths phase

“…(4), for (La 033 Sm 0.67 ) 0.67 Sr 0.33 MnO 3 , to be 1.7 Â 10 6 K, in reasonable agreement with those for La 0.7 Sr 0.3 MnO 3 (T 0 ¼2.55 Â 10 6 K), La 0.35 Pr 0.15 Ca 0.16 Sr 0.34 MnO 3 (T 0 ¼1.5 Â 10 6 K), and La 0.31 Sm 0.19 Sr 0.5 MnO 3 (T 0 ¼2.8 Â 10 6 K) manganites, characterized by disorder in rare-earth and alkaline-earth ions. VRH conductivity mechanism clearly applies for explanation of charge transfer in all these compounds [26]. It is noted that the VRH model was also used to explain the electrical properties of (La 0.4 Sm 0.6 ) 0.67 Sr 0.33 MnO 3 , which is quite similar to (La 033 Sm 0.67 ) 0.67 Sr 0.33 MnO 3 , in the paramagnetic region [3].…”

Metallic and semi-conducting resistivity behaviour of La0.7Ca0.3−x K x MnO3 (x = 0.05, 0.1) manganites

“…The estimated electron parameters for La 0.7-Ca 0.25 K 0.05 MnO 3 (La 0.7 Ca 0.2 K 0.1 MnO 3 ) are the Fermi wave vector k F = 3.581 (4.586) 9 10 7 cm -1 , the Fermi velocity v F = 2.035 (2.105) 9 10 7 cms -1 and the plasma frequency x p = 1.406 (1.831) eV. We stress that the effects induced by electron correlations and mass renormalizations by electron-electron interactions are crucial in magnetic systems such as doped manganites [55][56][57][58][59][60][61][62][63][64][65].…”

“…We notice that enhanced electron mass m * = 2.031 (2.514) m e in La 0.7 Ca 0.3-x K x MnO 3 leads to the reduced plasma frequency, and hence the reduced zero temperature elastic scattering rate in comparison to conventional metals. It is perhaps worth noticing that, in holedoped manganites, the scattering rate at low temperatures is of the order of 10 15 s -1 [55][56][57][58][59][60][61][62][63][64][65]. Furthermore, the MottIoffe-Regel criterion for metallic conductivity is valid, as the deduced mean free path is larger than the Mn-O bond length.…”