arXiv subjects

J. Mohanty

Publications and source records attributed to J. Mohanty.

3 recordsLinked to original sources

arXiv2026

Phase-Transition Induced Magnetic Domain Evolution and Magnetization Dynamics in FePt/FeRh Bilayers for Advanced Heat-Assisted Magnetic Recording

Achieving ultrahigh recording densities with low power consumption is a central challenge for next generation heat assisted magnetic recording (HAMR), as conventional L10 FePt media require intense laser heating due to their high coercivity (Hc) and high Curie temperature (700 K). Here, we address this issue using FePt/FeRh bilayers, where the antiferromagnetic to ferromagnetic transition of FeRh near 350 K generates strong interfacial exchange coupling that assists magnetization switching in the FePt layer. Magnetometry measurements reveal a 40% reduction in Hc from 300 K to 400 K in the bilayer, compared to only 8% in single layer FePt. Temperature dependent MFM directly captures phase transition induced domain evolution, showing a 30% reduction in domain size and enhanced phase contrast. TR-MOKE measurements reveal only a minor (0.4 T) modification of the effective anisotropy field during phase transition, confirming that the intrinsic anisotropy of FePt remains largely preserved. These results demonstrate that the reduction in Hc in FePt/FeRh bilayers is primarily governed by phase transition induced domain wall mobility coupled with interfacial magnetic interactions, rather than by intrinsic anisotropy softening. This mechanism provides a pathway toward efficient magnetization switching under reduced thermal load, making FePt/FeRh heterostructures promising candidates for advanced HAMR media.

cond-mat.mtrl-sci↗

arXiv2020

Effect of Ti underlayer thickness on the magnetic anisotropy of TbFe thin films

In this study, we address the impact of Ti underlayer thickness (UL: 0-40 nm) on the structural, magnetic, and microscopic properties of TbFe thin films. The structural analysis confirmed the intermixing at interfaces of the Ti and TbFe layer with the increment of UL thicknesses. Out-of-plane (OOP) coercivity (Hc), and saturation field (Hs) gradually increased with an increase in UL thickness regardless of interface mixing. For UL = 10 nm, the domain contrast and OOP stray field strength were enhanced, which may be due to the extent of d-d hybridization dominated over the influence of interfacial roughness. While for UL = 20, and 40 nm, the extent of interfacial roughness dominated the hybridization effects and as a result, stray fields deteriorated. By placing UL of 20 nm, Hc increased by nearly 6 times more than the bare TbFe system. So, we observe a state with high OOP Hc combined with nearly zero OOP stray fields that are found to co-exist in the sample. The magnetization reversal studies on a large area reveal domain nucleation followed by domain-wall motion in all the films. The idea of tuning magnetic properties by varying thicknesses of Ti UL may useful in spintronics applications.

cond-mat.mes-hall↗

arXiv2018

Modification of microstructure and micromagnetic properties in Gd-Fe thin films by rapid thermal processing

Impact of rapid thermal processing (RTP) on microstructure and magnetic properties of Gd-Fe thin films have been investigated with a special emphasis to magnetic microstructure. 100 nm thick amorphous Gd-Fe film shows elongated stripe domains with characteristic feature size of 122 nm, which signifies the development of perpendicular magnetic anisotropy (PMA) in this system. RTP at 550^oC for different time intervals viz. 5, 10, 15, 20 minutes induces the crystallization of Fe over the amorphous Gd-Fe matrix. Cross-sectional imaging with transmission electron microscope reveals the presence of Fe nanocrystal and the reacted film-substrate interface, which has also been verified by Rutherford backscattering spectrometry. With increasing RTP time, the characteristic size and the threshold height of the topographic feature increases. While the magnetic contrast drops down for the processed films, the increasing threshold height of the nanocrystalline grains results a topography dominated mixed phase in the magnetic force microscopy images. The magnetization measurements clearly indicate a re-orientation of the magnetization direction from perpendicular to the plane of the surface. To unravel the effect of anisotropy modification on domain structure, 3D micromagnetic simulations have been performed, which showed that with 50% reduction of original anisotropy, the magnetization tries to orient in the plane of the surface, whereas an in-plane (along xz plane) tilt angle of 30^o has been estimated to be the threshold for the decrease in perpendicular component of magnetization in the investigated Gd-Fe thin film system.

cond-mat.mes-hall↗