Insight into the negative magnetization and anomalous exchange-bias in DyFe5Al7 through neutron depolarization and neutron diffraction studies

Mr Deepak; Amit Kumar; S M Yusuf; E V Sampathkumaran

doi:10.1088/1361-648X/aca24d

Insight into the negative magnetization and anomalous exchange-bias in DyFe5Al7 through neutron depolarization and neutron diffraction studies

J Phys Condens Matter. 2022 Nov 11. doi: 10.1088/1361-648X/aca24d. Online ahead of print.

Authors

Mr Deepak¹, Amit Kumar², S M Yusuf³, E V Sampathkumaran⁴

Affiliations

¹ Bhabha Atomic Research Centre Solid State Physics Division, SOLID STATE PHYSICS DIVISION, Mumbai, Maharashtra, 400085, INDIA.
² Solid State Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai, 400085, INDIA.
³ Bhabha Atomic Research Centre, SOILD STATE PHYSICS DIVISION, Mumbai, 400085, INDIA.
⁴ Homi Bhabha Centre for Science Education, V N Purav Marg, Mankhurd, Mumbai, 400088, INDIA.

PMID: 36368049
DOI: 10.1088/1361-648X/aca24d

Abstract

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.

Keywords: Exchange bias; Negative magnetization; Spin reorientation.