Phase stability, single crystal growth, and anisotropic magnetic properties of Ca–La magnetoplumbite-type ferrite

Single crystal synthesis and magnetic properties of Co2+-substituted and non-substituted magnetoplumbite-type Na–La ferrite

“…T C s for #1-4 are 700-710 K, which are comparable to the previous report for M-type Na-La ferrite [7] and M-type Ca-La ferrite [13], and lower compared to typical M-type ferrites (720 -740 K). The reduced T C may be attributed to the interruption of the super-exchange interaction between ferric ions by Fe 2+ and/or Co 2+ .…”

“…It is notable that M ⊥ at T = 5 K shows a rapid increase at around H = 7 kOe, indicating a spin-flip transition. A similar magnetization process has been observed for M-type Ca-La ferrite [13]. The initial slope increases with temperature, suggesting the increase of MA.…”

“…We also found that x + y exceeds 1 by about 0.05 for all samples. A similar nonstoichiometry has been pointed out in an analogue M-type Ca-La ferrite [11,12,13]. Two models for the nonstoichiometry in M-type Ca-La ferrite have been proposed: occupation of a part of Ca 2+ at Fe sites [12,14], and the presence of stacking faults in A/O packing [15].…”

“…H A of SrM, which is almost temperature-independent below room temperature, is also shown for comparison. H A of #1 is less than that of SrM for all temperatures and decreases with decreasing temperature similar to M-type Ca-La ferrite [13]. The further drop below 100 K is attributed to the spin-flip transition discussed above.…”

“…A comparison of the temperature dependence of H A among La-Co co-substituted M-type ferrites with different A site ions demonstrates that the Co 2+ concentration is not the sole factor affecting the enhancement of the uniaxial MA. For example, H A of La-Co CaM with w = 0.1 (#2 in the reference [4]), which has a comparable amount of Co 2+ to #2 in this study, The data for SrM is taken from our previous report [13]. The inset shows the w (Co 2+ concentration) dependence of H A for 5 and 300 K.…”