Prakash Pulkit, Mishra S K, Prajapat C L, Das A
Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, India.
Homi Bhabha National Institute, Mumbai 400094, India.
J Phys Condens Matter. 2021 Feb 24;33(15). doi: 10.1088/1361-648X/abde66.
We have studied the magnetic structure, spin reorientation behaviour and dielectric properties of polycrystalline HoMnFeO(0.0 ⩽⩽ 0.25) compounds using magnetization, neutron diffraction and dielectric measurements. These compounds crystallize predominantly in the hexagonal phase (6) with a small phase fraction of the orthorhombic phase () which increases with increase in dopant concentration and a total suppression of the hexagonal phase is observed at= 0.25. Doping Fe at the Mn site leads to an increase in the spin reorientation temperature () from 33 K (= 0) to 55 K (= 0.1) while theremains nearly constant at 72 K. The magnetic structure of the hexagonal phase was found to be Γ(6'') belowand Γ(6'') below. The magnetic ordering temperature of Hoions at 2(a) site appears to coincide with theonly in the case of= 0 sample. The Ho ions at 4(b) site are found to magnetically order below 8 K. Theof the Ho ions at both 4(b) and 2(a) sites do not appear to be affected by doping at the Mn site. The temperature variation of the Mn and Ho moments follow the Brillioun function dependence albeit with differing values of the molecular field constantand. Short range magnetic order alone was found for the completely orthorhombic sample (= 0.25). An anomalous suppression of the dielectric constant () atis observed in the case of hexagonal samples. Further, a linear correlation between Δ(=(T) -(0)) and the square of the antiferromagnetic moment, is observed in these compounds.
我们使用磁化强度、中子衍射和介电测量方法，研究了多晶 HoMnFeO（0.0⩽⩽0.25）化合物的磁结构、自旋重取向行为和介电性质。这些化合物主要结晶为六方相（6），存在少量正交相（），且正交相的比例随掺杂浓度的增加而增大，在 = 0.25 时观察到六方相完全被抑制。在 Mn 位点掺杂 Fe 会导致自旋重取向温度（）从 33 K（= 0）升高到 55 K（= 0.1），而在 72 K 时几乎保持不变。发现六方相的磁结构在 以下为 Γ(6'')，在 以下为 Γ(6'')。仅在 = 0 的样品中，2(a) 位点的 Ho 离子的磁有序温度似乎与 重合。发现 4(b) 位点的 Ho 离子在 8 K 以下发生磁有序。4(b) 和 2(a) 位点的 Ho 离子的 似乎不受 Mn 位点掺杂的影响。Mn 和 Ho 磁矩的温度变化遵循布里渊函数依赖关系，尽管分子场常数 和 的值不同。对于完全正交的样品（= 0.25），仅发现了短程磁有序。在六方样品中观察到在 时介电常数（）出现异常抑制。此外，在这些化合物中观察到 Δ（= (T) - (0)）与反铁磁矩的平方之间存在线性相关性。
