arXiv subjects

Bhuvneshwari Sharma

Publications and source records attributed to Bhuvneshwari Sharma.

4 recordsLinked to original sources

arXiv2025

Thermal Evolution of Skyrmions in Synthetic Ferrimagnets of Co/Gd Heterostructure for Topological Spintronic Applications

Synthetic ferrimagnetic (SFiM) multilayers offer a versatile platform for hosting skyrmions with tunable magnetic properties, combining the advantages of ferromagnets and antiferromagnets. Unlike synthetic antiferromagnets, SFiMs retain a finite magnetization that allows direct observation of magnetic textures while still benefiting from reduced dipolar fields and a suppressed skyrmion Hall effect. However, a systematic investigation of their temperature and field dependent magnetization evolution, including the labyrinthine-to-skyrmion transition in Co/Gd-based SFiMs, remains less explored. Here, we demonstrate the stabilization of 70 nm-radius skyrmions at room temperature and reveal how the Co and Gd sublattices influence the temperature-dependent net magnetization. Further, we develop a microscopic spin model for SFiM incorporating the relevant magnetic interactions, which reproduces the experimental observations and captures the temperature-dependent magnetic phase evolution. This framework highlights the interplay of fundamental interactions controlling skyrmion stability in SFiM and provides a pathway for engineering heterostructures for topological spintronic applications.

cond-mat.mtrl-sci↗

arXiv2025

Effect of RKKY and dipolar interaction on the nucleation of skyrmion in Pt/Co multilayer with Ir spacer

Magnetic skyrmions, topologically protected spin textures, have emerged as promising candidates for next-generation spintronic applications. In this study, we investigate the stabilization of skyrmionic states in a uniquely engineered Pt/Co multilayer system with an Ir spacer, where both Ruderman Kittel Kasuya Yosida (RKKY) and dipolar interactions play a crucial role. The studied multilayer structure consists of a synthetic antiferromagnetic (SAF) configuration, where a single Ir layer facilitates strong antiferromagnetic coupling between two ferromagnetic regions: FM1 (top) and FM2 (bottom), each formed by repeated Co layers separated by Pt, enabling significant dipolar interactions. This FM1/Ir/FM2 configuration results in a distinctive skyrmionic hysteresis loop, driven by the interplay of dipolar and RKKY interactions. Magnetic force microscopy (MFM) imaging confirms the nucleation of isolated skyrmions, while magnetotransport measurements reveal a finite topological Hall effect (THE), indicating the chiral nature of these spin textures. Furthermore, we demonstrate that increasing the Co layer thickness leads to a reduction in magnetic anisotropy, which in turn results in the formation of relatively larger and denser skyrmions. Our findings establish a robust approach for stabilizing skyrmions through the combined effects of dipolar and RKKY interactions, offering new pathways for controlled skyrmion manipulation in spintronic devices.

cond-mat.mtrl-sci↗

arXiv2025

Tailoring the Topological Hall Effect in Pt/Co/X (X = Ta, Re) thin films

Electron transport combined with magnetism has gained more attention to the spintronics community in the last few decades. Among them, the topological Hall effect (THE), which arises due to the emergent magnetic field of a non-trivial object, is found to be a promising tool for probing the presence of skyrmions. A sizeable Dzyaloshinskii-Moriya interfacial interaction (iDMI) with reduced effective anisotropy can stabilize skyrmions in thin films. Recently, a large iDMI has been predicted in Pt/Co/Re thin film. Here, we investigate the influence of various magnetic interactions on the THE in perpendicularly magnetized Pt/Co/X (X = Ta, Re) thin films. The presence of skyrmions is confirmed via THE and magnetic force microscope (MFM) imaging. Notably, two distinct types of THE signals are observed in the different samples, which are explained using micromagnetic simulations. Our results reveal that exchange interaction, iDMI, effective anisotropy, and saturation magnetization contribute significantly in determining the variations in topological Hall resistivity behavior, which arise from different skyrmionic phases. These findings contribute to the development of novel material systems featuring different skyrmionic phases with potential applications in spintronics.

cond-mat.mtrl-sci↗

arXiv2023

Structural deformation and irreversible magnetic properties of flexible Co/Pt and Co/Pd thin films

The successful commercialization of flexible spintronic devices requires a complete understanding of the impact of external strain on the structural, electronic, and magnetic properties of a system. The impact of bending-induced strain on flexible films is studied quite well. However, little is known about the effect of other modes of flexibility, e.g., wrinkling, twisting, peeling, and stretching on the functional properties of flexible films. In this context, perpendicular magnetic anisotropic Co/Pt and Co/Pd thin films are prepared on flexible Kapton substrates, and the impact of the peeling mode is studied in detail. The peeling method generates numerous cracks, and buckling in the thin film, along with localized blister formation imaged by scanning electron microscopy. Further, the resistivity measurement confirms a significant enhancement in sample resistance owing to the severe damage of the films. The structural discontinuities strongly affect the magnetization reversal phenomena as measured by the magneto-optic Kerr effect (MOKE)-based microscopy. The bubble domains got converted to elongated-shaped domains due to several hindrances to the wall motion after strain application. Further, the relaxation measurements reveal that the thermal energy is insufficient to switch the magnetization at a few areas due to their high pinning potential associated with the damages. In contrast to bending-induced strain, here, all the modifications in the functional properties are found to be irreversible in nature.

cond-mat.mtrl-sci↗