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Modification of magnetic ground state in Tb2Ni0.90Si2.94 by thermal annealing
Intermetallics ( IF 4.4 ) Pub Date : 2020-09-01 , DOI: 10.1016/j.intermet.2020.106874
Santanu Pakhira , R.N. Bhowmik , Maxim Avdeev , R. Ranganathan , Chandan Mazumdar

Abstract In this work, we have investigated the thermal annealing effect on the physical properties of an AlB 2 -type ternary intermetallic compound, Tb 2 Ni0.90Si2.94, that undergoes spin freezing behaviour coexisting with spatially limited antiferromagnetic phase below 9.9 K in as-cast form. Thermal annealing effect is found to result in considerable changes in the magnetic ground state properties of the system. Though only one magnetic transition around 9.9 K is observed for as-cast compound, the annealed sample exhibits two distinct magnetic transitions; one around T N ∼ 13.5 K and another around T f ∼ 4 K. The magnetization measurements and zero field neutron diffraction study reveal that the high temperature transition is antiferromagnetic type, though of limited correlation length, while the low temperature transition corresponds to spin freezing behaviour. The ac susceptibility and heat capacity studies also confirm the existence of frustrated cluster glass state at lower temperature than the antiferromagnetic ordering temperature. Additionally, ac susceptibility data exhibits signature of an additional peak in the even lower temperature region (at 2.2 K for zero frequency) that tends to shift in opposite direction with frequency in contrast to that observed for conventional glassy transitions. The change in intrinsic local structural disorder of Ni and Si ions associated with annealing has been argued to be responsible for the different magnetic behaviour in as-cast and annealed samples.

中文翻译:

热退火对 Tb2Ni0.90Si2.94 中磁性基态的改性

摘要 在这项工作中,我们研究了热退火对 AlB 2 型三元金属间化合物 Tb 2 Ni0.90Si2.94 物理性质的影响,该化合物经历自旋冻结行为,与低于 9.9 K 的空间受限反铁磁相共存,如- 铸造形式。发现热退火效应会导致系统的磁基态特性发生相当大的变化。尽管对于铸态化合物仅观察到 9.9 K 附近的一个磁转变,但退火样品表现出两种不同的磁转变;一个在 TN ∼ 13.5 K 附近,另一个在 T f ∼ 4 K 附近。磁化测量和零场中子衍射研究表明,高温转变是反铁磁类型的,尽管相关长度有限,而低温转变对应于自旋冻结行为。交流磁化率和热容量研究也证实了在比反铁磁有序温度更低的温度下存在受挫团簇玻璃态。此外,交流磁化率数据显示出在更低温度区域(零频率为 2.2 K)中的附加峰的特征,与常规玻璃态转变观察到的峰相比,该峰倾向于随频率向相反方向移动。与退火相关的 Ni 和 Si 离子的固有局部结构无序的变化被认为是铸态和退火样品中不同磁性行为的原因。交流磁化率和热容量研究也证实了在比反铁磁有序温度更低的温度下存在受挫团簇玻璃态。此外,交流磁化率数据显示出在更低温度区域(零频率为 2.2 K)中的附加峰的特征,与常规玻璃态转变观察到的峰相比,该峰倾向于随频率向相反方向移动。与退火相关的 Ni 和 Si 离子的固有局部结构无序的变化被认为是铸态和退火样品中不同磁性行为的原因。交流磁化率和热容量研究也证实了在比反铁磁有序温度更低的温度下存在受挫团簇玻璃态。此外,交流磁化率数据显示出在更低温度区域(零频率为 2.2 K)中的附加峰的特征,与常规玻璃态转变观察到的峰相比,该峰倾向于随频率向相反方向移动。与退火相关的 Ni 和 Si 离子的固有局部结构无序的变化被认为是铸态和退火样品中不同磁性行为的原因。2 K(零频率),与常规玻璃态转变观察到的情况相反,它倾向于随频率向相反的方向移动。与退火相关的 Ni 和 Si 离子的固有局部结构无序的变化被认为是铸态和退火样品中不同磁性行为的原因。2 K(零频率),与常规玻璃态转变观察到的情况相反,它倾向于随频率向相反的方向移动。与退火相关的 Ni 和 Si 离子的固有局部结构无序的变化被认为是铸态和退火样品中不同磁性行为的原因。
更新日期:2020-09-01
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