Growth and characterization of La2CoMnO6 crystals doped with Pb

Magnetic behavior of La2CoMnO6− crystal doped with Pb and Pt

“…4 with the selection rules in Table 1 points indeed to monoclinic symmetry as only two types of Raman modes are encountered. The peaks at 105, 230, 525, and 628 cm À1 can be assigned to A g modes in accordance with our previous work [7]. The peak at 622 cm À1 in the X'(Z'Y)X' and the X(YZ)X spectrum fulfills the selection rules for a B g mode (see inset of Fig.…”

“…The ionic radii of these cations are: i r (La 3+ ) = 1.36 Å (in cubo-octahedral coordination) [15], i r (Co 2+ ) = 0.745 Å (octahedral coordination, high spin state) and i r (Mn 4+ ) = 0.53 Å (intermediate spin state, octahedral coordination) [15]. According to the present SEM/EDX results and our previous observations [7] it should be assumed that the A position is occupied by La/Pb in proportion of 1.67/0.33. La-positions seem the only possible ones to accommodate Pb 2+ since i r (Pb 2+ ) = 1.49 Å (in cubo-octahedral coordination [15]).…”

“…The statistical parameters for both groups are quite similar as was shown in Ref. [7] where it was demonstrated that a crystal with a similar composition could be refined in both space groups. Hence, while the determined lattice parameters can be regarded as correct for both possible structures, additional studies with other experimental methods are needed to unambiguously establish the lattice symmetry.…”

“…The monoclinic lattice exhibits long-range order in B 0 /B 00 positions, while in the orthorhombic lattice B 0 and B 00 ions share identical crystallographic positions [2,3]. It was shown that in La 2 CoMnO 6 bulk materials as well as in thin films the orthorhombic and the monoclinic phases exist simultaneously [4][5][6][7]. Dass and Goodenough [8] established that long-range B 0 /B 00 -sites ordered La 2 CoMnO 6Àd undergoes a ferromagnetic (FM) transition at Curie temperature T C $ 225 K and has saturation magnetization M s of nearly 6 m B /f.u., whereas the disordered (orthorhombic) La 2 CoMnO 6Àd exhibits a FM transition in the range of 134-148 K with M s $ 3.5 m B /f.u.…”

Magnetic and electric field characterization of La2CoMnO6 crystals doped with Pb

“…and a disordered one with T C in the range of 134–148 K and M s ∼ 3.5 µ B /f.u.. The growth of single crystals is additionally complicated by the narrow phase homogeneity area of La 2 CoMnO 6 and the slowness of the growth process, and there are only few works on characterization of single crystals . However, despite the mentioned difficulties, the observation of magnetodielectric and magnetoresistance effects near room temperature in La 2 NiMnO 6 revived the interest in La 2 CoMnO 6 .…”