Abdullah Md F, Pal P, Chandrakanta K, Jena R, Devi S, Yadav C S, Singh A K
Department of Physics and Astronomy, National Institute of Technology, Rourkela-769008, Odisha, India.
J Phys Condens Matter. 2020 Mar 27;32(13):135701. doi: 10.1088/1361-648X/ab5c2b.
We have reported a systematic investigation on structural, magnetic, magnetodielectric and magnetoimpedance characteristics of Y-type BaMg(Fe Mn )O (0 ⩽ x ⩽ 0.12) hexaferrite synthesized by solid-state reaction route. Rietveld refinement of x-ray diffraction pattern confirms the phase purity of all the samples with rhombohedral crystal structure. The Mn dopant modulates not only superexchange angle near to the boundary of magnetic blocks but also magnetic transition temperature. Temperature-dependent magnetization data suggests that due to Mn doping at Fe sites, ferrimagnetic to proper screw transition temperature (T ) increases from 190 K to 208 K, while there is a decrease in proper screw to longitudinal conical spin transition temperature (T ) from 35 K to 25 K. We observe remarkable decrease in the magnetic field from 20 kOe to 12 kOe to produce intermediate spin ordering from ferrimagnetic ordering which can be understood because of modification of superexchange angle due to Mn doping. The value of loss tangent decreases with increasing doping concentration at 300K, i.e. 60% and 180% in BMFM4 (x = 0.04) and BMFM8 (x = 0.08) respectively as compared to BMF, suggesting the evolution of intrinsic feature in the doped samples. Magnetodielectric (MD) effect shows that in the low-frequency regime, the robust MD effect is because of Maxwell-Wagner interfacial polarization, whereas in the high-frequency regime intrinsic effect dominates. Further, magnetoimpedance measurement confirms the presence of substantial intrinsic MD% (6%) at 1.3 T applied field at 300 K for 4% Mn-doped sample. Finally, the nature and strength of magnetoelectric coupling in BMFM4 and BMFM8 samples at 300 K is found to be biquadratic (P M ) and maximum strength of coupling is 3.09 × 10 emu g and 2.34 × 10 emu g, respectively.
我们报道了对通过固态反应路线合成的Y型BaMg(Fe Mn )O (0 ⩽ x ⩽ 0.12) 铁氧体的结构、磁性、磁电介质和磁阻抗特性进行的系统研究。X射线衍射图谱的Rietveld精修证实了所有具有菱面体晶体结构的样品的相纯度。Mn掺杂不仅调节了靠近磁块边界的超交换角，还调节了磁转变温度。与温度相关的磁化数据表明，由于在Fe位点处进行Mn掺杂，亚铁磁到适当螺旋转变温度（T ）从190 K增加到208 K，而适当螺旋到纵向锥形自旋转变温度（T ）从35 K降低到25 K。我们观察到产生从亚铁磁有序到中间自旋有序的磁场从20 kOe显著降低到12 kOe这一现象，这可以归因于Mn掺杂导致的超交换角的改变。在300K时，损耗角正切值随掺杂浓度增加而降低，即与BMF相比，BMFM4（x = 0.04）和BMFM8（x = 0.08）中的损耗角正切值分别降低了约60%和180%，这表明掺杂样品中固有特性的演变。磁电介质（MD）效应表明，在低频区域，强大的MD效应是由于麦克斯韦 - 瓦格纳界面极化，而在高频区域，固有效应占主导。此外，磁阻抗测量证实，对于4% Mn掺杂的样品，在300 K、1.3 T的外加磁场下存在相当大的固有MD%（约6%）。最后，发现BMFM4和BMFM8样品在300 K时的磁电耦合性质和强度为双二次型（P M ），耦合的最大强度分别为3.09 × 10 emu g和2.34 × 10 emu g。
