Singh H, Skoulatos M, Joshi D C, Pramanik P, Roy-Chowdhury M, Ghosh S, Jena S K, Dey J K, Thota S
Department of Physics, Indian Institute of Technology, Guwahati 781039, Assam, India.
Heinz Maier-Leibnitz Zentrum (MLZ) and Physics Department, Technical University of Munich, D-85748 Garching, Germany.
J Phys Condens Matter. 2024 May 7;36(31). doi: 10.1088/1361-648X/ad4223.
We report the experimental determination of the magnetic exchange parameter (J/kB= 2.88 ± 0.02 K) for the Spin-3/2 ferromagnetic (FM) Kagomé lattice system: CoVOusing the temperature dependence of dc-magnetic susceptibility() data by employing the fundamental Heisenberg linear chain model. Our results are quite consistent with the theoretically reported nearest neighbor dominant FM exchange coupling strengthJex-NN∼2.45 K. Five different magnetic phase transitions (6.2-11.2 K) and spin-flip transitions (9.6-7.7 kOe) have been probed using the∂(χT)/∂Tvs., heat capacity (-) and differential isothermal magnetization curves. Among such sequence of transitions, the prominent ones being incommensurate antiferromagnetic (AFM) state at 11.2 K, commensurate AFM state at 8.8 K, and commensurate FM state across 6.2 K. All the successive magnetic phase transitions have been mapped onto a single H-T plane through which one can easily distinguish the above-mentioned different phases. The magnetic contribution of the-near(11.2 K) has been analyzed using the power-law expressionCM=A|T-TN|-αresulting in the critical exponent= 0.18 ± 0.01 (0.15 ± 0.003) for<(>), respectively for the CoVO. It is interesting to note that non-Debye type dipole relaxation is quite prominent in CoVOand was evident from the Kohlrausch-Williams-Watts analysis of complex modulus and impedance spectra (0⩽β⩽1). Mott's variable-range hopping of charge carriers process is evident through the resistivity analysis (ρac--1/4) in the temperature range 275 C-350 C. Moreover, the frequency-dependent analysis ofσac() follows Jonscher's power law yielding two distinct activation energies (Ea∼0.37 and 2.29 eV) between the temperature range 39 C-99 C and 240 C-321 C.
我们报告了利用基本的海森堡线性链模型，通过直流磁化率（χ）数据的温度依赖性，对自旋 - 3/2铁磁（FM） Kagomé晶格系统CoVO的磁交换参数（J/kB = 2.88 ± 0.02 K）进行的实验测定。我们的结果与理论报道的最近邻主导的FM交换耦合强度Jex - NN ∼ 2.45 K相当一致。利用∂(χT)/∂T对T、热容（C）和微分等温磁化曲线，探测了五个不同的磁相变（6.2 - 11.2 K）和自旋翻转转变（9.6 - 7.7 kOe）。在这样一系列的转变中，突出的转变包括11.2 K时的非公度反铁磁（AFM）态、8.8 K时的公度AFM态以及跨越6.2 K的公度FM态。所有连续的磁相变都被映射到一个单一的H - T平面上，通过该平面可以轻松区分上述不同相。利用幂律表达式CM = A|T - TN|-α对接近（11.2 K）时的磁贡献进行了分析，对于CoVO，分别在T < TN（T > TN）时得到临界指数α = 0.18 ± 0.01（0.15 ± 0.003）。有趣的是，非德拜型偶极弛豫在CoVO中相当显著，这从复模量和阻抗谱的科尔劳施 - 威廉姆斯 - 瓦特分析（0⩽β⩽1）中可以明显看出。通过在275 C - 350 C温度范围内的电阻率分析（ρac ∼ T-1/4），电荷载流子的莫特变程跳跃过程很明显。此外，在39 C - 99 C和240 C - 321 C温度范围内，σac（ω）的频率依赖性分析遵循琼舍尔幂律，产生两个不同的激活能（Ea ∼ 0.37和2.29 eV）。
