In this equation, x and y denotes the number of moles of RE and Mn atoms per formula unit of the structure, respectively. The RE and Mn represent the theoretical magnetic moment of trivalent free RE3+ ions and divalent Mn2+ ions respectively. The experimental values of total magnetic moments were found to be smaller than the calculated values (Table xyz). The crystal field effects can lead to lower value of magnetic moments for RE3+ ions in these compositions as compared to free RE3+ ions, which in turn could lower the total magnetic moment of these compositions. This discrepancy in the total magnetic moment values could also be due to the presence of secondary phases in these samples. The antiferromagnetic ordering temperature (TN) and
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On the contrary, Ca13PrMnSb11 does not show ferromagnetic ordering. Interestingly, Pr-compound shows an antiferromagnetic ordering transition below 13 K. It should be noted that this sample contains a small amount of unknown secondary phase and hence, it is not possible to ascertain whether this antiferromagnetic transition is intrinsic to the Ca13PrMnSb11 phase or coming from the secondary phase. These ferromagnetic ordering temperatures are lower than the parent Ca14MnSb11 (TC = 65 K). The positive Weiss temperature (θp) of 0.64(1) K for Ca13NdMnSb11 is consistent with the ferromagnetic behavior. However, in case of Ca13SmMnSb11, the negative value of θp (-7.9(1) K) indicates the antiferromagnetic interactions along with the ferromagnetic interactions. This behavior is may be due to antiferromagnetic ordering of Sm spins at low temperatures (below 5 K). Future magnetic measurements at low temperatures (below 5 K) would be interesting to probe these …show more content…
However, in case of Ca13LaMnSb11, where one mole of La3+ is doped per formula unit, one should not expect to see ferromagnetic ordering of Mn moments since there are no hole carriers are available to mediate ferromagnetic ordering through RKKY interactions. Similar contrasting behavior was also observed in the case of Yb14xCexMnSb11 series where the Tc was systemically lowered to 39 K till ‘x’ = 0.45 composition, but further increase in Ce substitution has no effect on the ferromagnetic ordering temperature8. In case of Cedoped Ca13CeMnSb11 compound, Tc further shifted to lower temperature (Tc = 38 K) and finally a complete suppression of Tc was achieved for Ca13PrMnSb11 which showed antiferromagnetic ordering transition (TN) below 13 K. It is not clear that whether Pr spins or Mn spins are ordering antiferromagnetically in this compound. Interestingly, Ca13NdMnSb11 again showed Tc at 36 K which increased to 50 and 52 K for Ca13SmMnSb11 and Ca13GdMnSb11, respectively. These results are surprising since Gd3+ ions have largest magnetic moments among LaGd metals. It should be noted that the CaMn distances are shortest between Ca2 and Mn atoms. The Gd atoms in Ca13GdMnSb11 are heavily
On the contrary, Ca13PrMnSb11 does not show ferromagnetic ordering. Interestingly, Pr-compound shows an antiferromagnetic ordering transition below 13 K. It should be noted that this sample contains a small amount of unknown secondary phase and hence, it is not possible to ascertain whether this antiferromagnetic transition is intrinsic to the Ca13PrMnSb11 phase or coming from the secondary phase. These ferromagnetic ordering temperatures are lower than the parent Ca14MnSb11 (TC = 65 K). The positive Weiss temperature (θp) of 0.64(1) K for Ca13NdMnSb11 is consistent with the ferromagnetic behavior. However, in case of Ca13SmMnSb11, the negative value of θp (-7.9(1) K) indicates the antiferromagnetic interactions along with the ferromagnetic interactions. This behavior is may be due to antiferromagnetic ordering of Sm spins at low temperatures (below 5 K). Future magnetic measurements at low temperatures (below 5 K) would be interesting to probe these …show more content…
However, in case of Ca13LaMnSb11, where one mole of La3+ is doped per formula unit, one should not expect to see ferromagnetic ordering of Mn moments since there are no hole carriers are available to mediate ferromagnetic ordering through RKKY interactions. Similar contrasting behavior was also observed in the case of Yb14xCexMnSb11 series where the Tc was systemically lowered to 39 K till ‘x’ = 0.45 composition, but further increase in Ce substitution has no effect on the ferromagnetic ordering temperature8. In case of Cedoped Ca13CeMnSb11 compound, Tc further shifted to lower temperature (Tc = 38 K) and finally a complete suppression of Tc was achieved for Ca13PrMnSb11 which showed antiferromagnetic ordering transition (TN) below 13 K. It is not clear that whether Pr spins or Mn spins are ordering antiferromagnetically in this compound. Interestingly, Ca13NdMnSb11 again showed Tc at 36 K which increased to 50 and 52 K for Ca13SmMnSb11 and Ca13GdMnSb11, respectively. These results are surprising since Gd3+ ions have largest magnetic moments among LaGd metals. It should be noted that the CaMn distances are shortest between Ca2 and Mn atoms. The Gd atoms in Ca13GdMnSb11 are heavily