Structural order, magnetic and intrinsic dielectric properties of magnetoelectric La 2 CoMnO 6

Calculation of the optical phonons in ordered Ba2MgWO6 perovskite using short‐range force field model

“…Such a particular result is in line with experimental data in Liegeois‐Duyckaerts and Tarte, in which the A 1g mode position in the Raman spectra of Ba 2 MgB″O 6 systems (B″ = U, W, Mo, Te) can be associated with the bonding energy E S of the stretching bond B″–O, that is, A 1g (W; 813 cm −1 ) > A 1g (Mo; 779 cm −1 ) > A 1g (U; 753 cm −1 ) > A 1g (Te; 724 cm −1 ) because E S (W–O) > E S (Mo–O) > E S (U–O) > E S (Te–O). This fact also corroborates several reported results in the literature concerning the sensibility of A 1g mode to detect B‐site local disorder in partially ordered perovskites …”

“…Unlike the case of the 1:2 ordered perovskites presenting the two‐phonon behavior for the A 1g breathing mode, antisite process only induces a one‐phonon behavior in 1:1 ordered systems. It means that the effect of disorder can be seen by following the peak parameters such as intensity I 0 , position ν and width Γ . Therefore, partially disordered perovskites only exhibit breathing modes with broadening due to the damping and a downshift attributed to the antisite defects that introduce a variation in the (B′,B″)–O force constant value.…”

“…Raman and infrared spectroscopy became a useful tool to probe local disorder at B‐site and octahedral tilting in ordered perovskites by analyzing peak parameters such as intensity, position, width, and possible asymmetry . As a result of disorder, the A 1g mode starts to depict a broadening as a consequence of the antisite defects.…”

Consequences of the CMR effect on EELS in TEM

“…On the basis of several investigations [5,7,6], which propose a temperature dependent magnetic behaviour, we study the influences of the CMR effect on Table 1 The values of two different interband transitions fitted by a Gaussian for both beam energies (40 keV and 200 keV) and both temperatures (85 K and RT).…”

“…Over the last decades double perovskite manganites have been of great interest in many fields such as cathodes of solid oxide fuel cells (SOFC) for high temperature applications [1], magnetic storage and magnetic field sensing functions at room temperature [2]. Their magnetic [3], electric [4], dielectric [5], magnetoelectric [6] and magnetoresistance [7] properties are promising for a wide variety of applications. In particular, the colossal magnetoresistance (CMR) of perovskite oxides is an interesting metal-insulator transition describing the change of the resistance in the presence of a magnetic field [8].…”