Deepak Mr, Kumar Amit, Yusuf S M, Sampathkumaran E V
Bhabha Atomic Research Centre Solid State Physics Division, SOLID STATE PHYSICS DIVISION, Mumbai, Maharashtra, 400085, INDIA.
Solid State Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai, 400085, INDIA.
J Phys Condens Matter. 2022 Nov 11. doi: 10.1088/1361-648X/aca24d.
We have provided the mesoscopic and microscopic understandings of polarity reversal of the magnetization or negative magnetization (NM) below TCOMP = 93 K in an exotic magnetic material containing three magnetic sublattices, viz., DyFe5Al7 crystallizing in ThMn12 structure, using neutron depolarization and neutron diffraction techniques. A full recovery of the neutron beam polarization at the TCOMP in a neutron depolarization experiment reveals a total compensation of magnetization inside the magnetic domains in the sample. The temperature-dependent neutron diffraction study under zero magnetic field has provided temperature dependencies of antiparallelly coupled Dy (MDy(2a)) and Fe (MFe(8f) and MFe(8j)) sublattice magnetic moments along [100] direction.Thedominance of |MDy(2a)| over total Fe moment, MFetotal = 4*|MFe(8f)| + |MFe(8j)|, below TCOMP leads to the NM in the compound. The magnetization versusmagnetic field curves below the TCOMP indicate the presence of field-induced spin reorientation in the compound. The magnetic field required for spin reorientation (HSR) is maximum at the lowest temperature and it decreases to zero as the temperature is increased to TCOMP. Interestingly, the compound shows a finite exchange-bias (HEB) below the TCOMP only, as evident from the field-cooled hysteresis loops, while at T > TCOMP,HEB is almost zero. The cooling-field (HCOOL) dependent study of HEB shows a slope change at HCOOL ~ HSR indicating a correlation of exchange-bias with spin-reorientation in the compound. This study, apart from revealing microscopic understanding of magnetic behavior of an exotic three magnetic sublattice system, provides a correlation among exchange-bias, magnetic compensation, and spin-reorientation phenomena.
我们利用中子去极化和中子衍射技术，对一种含有三个磁亚晶格（即具有ThMn12结构的DyFe5Al7）的奇异磁性材料中，低于TCOMP = 93 K时磁化强度的极性反转或负磁化强度（NM）进行了介观和微观层面的理解。在中子去极化实验中，TCOMP温度下中子束极化的完全恢复表明样品磁畴内的磁化强度得到了完全补偿。零磁场下随温度变化的中子衍射研究给出了反平行耦合的Dy（MDy(2a)）和Fe（MFe(8f)和MFe(8j)）亚晶格磁矩沿[100]方向的温度依赖性。在TCOMP以下，|MDy(2a)|超过总Fe磁矩MFetotal = 4*|MFe(8f)| + |MFe(8j)|，导致该化合物出现负磁化强度。TCOMP以下的磁化强度与磁场曲线表明该化合物中存在场致自旋重取向。自旋重取向所需的磁场（HSR）在最低温度时最大，随着温度升高到TCOMP，它减小到零。有趣的是，从场冷磁滞回线可以明显看出该化合物仅在TCOMP以下表现出有限的交换偏置（HEB），而在T > TCOMP时，HEB几乎为零。对HEB的冷却场（HCOOL）依赖性研究表明，在HCOOL ~ HSR处斜率发生变化，这表明该化合物中交换偏置与自旋重取向之间存在关联。这项研究除了揭示了对一个奇异的三磁亚晶格系统磁行为的微观理解外，还提供了交换偏置、磁补偿和自旋重取向现象之间的关联。
