arXiv subjects

Jyoti Ranjan Mohanty

Publications and source records attributed to Jyoti Ranjan Mohanty.

4 recordsLinked to original sources

arXiv2026

Thickness-Driven Control of Room Temperature Ferrimagnetic Skyrmions and their Topological Hall signature in GdFe Single Layers

Magnetic skyrmions are nanoscale, topologically protected spin textures with exceptional potential for high density data storage and energy efficient computing. Among various skyrmion hosting systems, rare earth transition metal ferrimagnets offer a promising platform due to their tunable magnetic properties and intrinsically low net magnetization. Despite this, the fundamental control of ferrimagnetic skyrmions in single layer films remains unexplored. Here, we demonstrate a viable route for engineering room temperature skyrmions in GdFe single layers through precise control of film thickness (60 to 80 nm). Thickness variation enables the systematic tuning of key magnetic parameters, including perpendicular magnetic anisotropy and saturation magnetization, thereby allowing precise control over skyrmion size and density. Magnetic force microscopy (MFM) reveals a clear thickness dependent evolution of isolated skyrmion characteristics, where skyrmion size decreases while skyrmion density increases with increasing GdFe film thickness, in agreement with micromagnetic simulations. At the same time, magnetotransport measurements show a systematic enhancement in the topological Hall resistivity with thickness, further corroborating the increased skyrmion density observed in MFM. Scanning transmission electron microscopy reveals a compositional gradient across the film thickness, indicative of structural asymmetry and potential inversion symmetry breaking, contributing to the emergence of a bulk Dzyaloshinskii Moriya interaction. Notably, sub 60nm skyrmions with high areal density are stabilized at room temperature. This work provides a viable route to tailor the properties of ferrimagnetic skyrmions in single-layer GdFe films, paving the way for the development of high-density ferrimagnetic skyrmionic devices.

cond-mat.mes-hall↗

arXiv2025

Spin Pumping in Magnetostrictive Galfenol Interfaced with Ta

In view of their advantages for memory and storage applications, the quest to find suitable magnetic thin film heterostructures that can exhibit strong spin pumping effect persists in the scientific community. Here, the spin pumping phenomenon is investigated in Ta/Galfenol (FeGa) thin film heterostructures by systematically varying the thickness of the heavy metallic Ta underlayer (UL). The films exhibit soft magnetic property with a bcc-phase with a notably low Gilbert damping obtained for FeGa on Si (100). The precessional magnetization dynamics of Ta/FeGa films are explored using time-resolved magneto-optical Kerr effect magnetometry, revealing the presence of a resonant Kittel mode and additional strain-induced modes. The lowest value of effective Gilbert damping in Ta/FeGa is obtained as ~ 0.015, which rises by ~ 65 % as the thickness of UL increases. Spin pumping and two-magnon scattering mechanisms are validated using a ballistic spin transport model. An overall effective spin mixing conductance value of ~ 5.48 $\times$ 10$^{15}$ cm$^{-2}$ is found, which is the highest value ever reported in magnetostrictive Galfenol films. Additionally, micromagnetic simulations are performed to understand the effect of tilted magnetic anisotropy on the formation of magnetic modes in these films. These findings in FeGa films establish it as an effective spin source material and offer innovative ideas to control spin-wave propagation and diverse applications in straintronics.

cond-mat.mtrl-sci↗

arXiv2024

Non-equillibrium ultrafast optical excitation as a stimulus for ultra-small field-free magnetic skyrmions in ferrimagnetic GdFeCo

Generating and manipulating magnetic skyrmions at ultrafast time scales is essential for future skyrmionbased racetrack memory and logic gate applications. Using the atomistic spin dynamics simulations, we demonstrate the nucleation of ultra-small field-free magnetic skyrmions in amorphous GdFeCo at picosecond timescales by femtosecond laser heating. The ultrafast nature of laser heating and subsequent cooling from a high-temperature state is crucial for forming magnetic skyrmion. The magnon localization and magnon coalescence are the key driving mechanisms responsible for stabilizing the magnetic skyrmions at zero field conditions. The polarization and, hence, the topological charge can be switched by exploiting the all-optical switching observed in GdFeCo. The skyrmion sizes and numbers can be controlled by varying pulse width and fluence of incident laser pulses. Applying an external magnetic field provides an additional degree of freedom to tune the skyrmion radius during the ultrafast optical creation of magnetic skyrmions. Our results provide a detailed understanding of the ultrafast creation of magnetic skyrmions using femtosecond laser pulses, a vital step in advancing next-generation skyrmion-based memory technologies.

cond-mat.mes-hall↗

arXiv2012

Unusual pattern formation on Si(100) due to low energy ion bombardment

In this paper evolution of silicon surface topography, under low energy ion bombardment, is investigated at higher oblique incident angles in the range of 63\degree-83\degree. Si(100) substrates were exposed to 500 eV argon ions. Different surface morphology evolves with increasing angle of incidence. Parallel-mode ripples are observed up to 67\degree which undergo a transition to perpendicular-mode ripples at 80\degree. However, this transition is not a sharp one but undergoes a series of unusual pattern formation at intermediate angles. Complete smoothening of silicon surface is observed at incident angles beyond 80\degree. The observed patterns are attributed to surface confined viscous flow and sputter erosion under ion bombardment.

cond-mat.mes-hall↗