Mohan Ashwin, S Vaidya Salil, Jain Anil, Yusuf S M
Department of Physics, Institute of Chemical Technology, Matunga, Mumbai 400019, India.
Solid State Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India.
J Phys Condens Matter. 2024 Jul 26;36(43). doi: 10.1088/1361-648X/ad636d.
The effect of partially substituting Tin (Sn) at the Manganese (Mn) site ofCa3Mn2O7, viz.Ca3Mn2-xSnxO7withx=0.03,0.05, on its structural and magnetic properties have been investigated using synchrotron diffraction, neutron diffraction, and bulk magnetization measurements. It is observed that with a substitution ofx=0.03, the minor (≈8%) tetragonal (I4/mmm) structural phase that is present in the predominantly orthorhombic (Cmc21) undopedCa3Mn2O7, completely disappears. The compounds order antiferromagnetically, the ordering temperature decreases with increasing Sn-content, indicating a weakening of the antiferromagnetic exchange interactions. Interestingly, in the ordered state, the spin magnetic moments which were aligned along the-axis of the unit cell in the undoped compound, are observed to have reoriented with their major components lying in the - plane in the Sn-doped compounds. The above influence of Sn-doping is seen to be stemming from a significant modification of the octahedral rotation and tilt mode geometry in the unit cell, that is known to be responsible for driving ferroelectricity in these compounds.
通过同步辐射衍射、中子衍射和体磁化强度测量，研究了在(Ca_3Mn_2O_7)的锰（(Mn)）位点部分取代锡（(Sn)），即(Ca_3Mn_{2 - x}Sn_xO_7)（(x = 0.03)，(0.05)）对其结构和磁性的影响。观察到，当(x = 0.03)时，主要为正交（(Cmc2_1)）结构的未掺杂(Ca_3Mn_2O_7)中存在的少量（约(8%)）四方（(I4/mmm)）结构相完全消失。这些化合物呈反铁磁有序，有序温度随(Sn)含量的增加而降低，表明反铁磁交换相互作用减弱。有趣的是，在有序状态下，未掺杂化合物中沿晶胞(c)轴排列的自旋磁矩，在(Sn)掺杂化合物中被观察到重新取向，其主要分量位于(ab)平面内。(Sn)掺杂的上述影响似乎源于晶胞中八面体旋转和倾斜模式几何结构的显著改变，已知这种改变是这些化合物中产生铁电性的原因。
