arXiv subjects

Kshitij Singh Rathore

Publications and source records attributed to Kshitij Singh Rathore.

4 recordsLinked to original sources

arXiv2026

Interface-resolved structural properties of epitaxial Y$_3$Fe$_5$O$_{12}$/ Gd$_3$Fe$_5$O$_{12}$ bilayers grown on GGG(111) by pulsed laser deposition

Epitaxial Y$_3$Fe$_5$O$_{12}$ (YIG) and Gd$_3$Fe$_5$O$_{12}$ (GdIG) thin films, along with their bilayer heterostructures, were grown on Gd$_3$Ga$_5$O$_{12}$(GGG)(111) substrates using pulsed laser deposition. Structural properties were investigated using X-ray diffraction, reciprocal space mapping, and cross-sectional transmission electron microscopy. The results confirm high crystalline quality and coherent epitaxial growth, with RSM revealing a coexistence of strained and partially relaxed regions governed by layer sequence. TEM analysis shows sharp interfaces, columnar microstructures, and antiphase boundaries that facilitate strain relaxation. A comparative study indicates that the GGG/YIG/GdIG stacking sequence exhibits improved structural quality with reduced defect density, attributed to the superior epitaxial growth of YIG on the substrate. These findings highlight the critical role of growth sequence in controlling strain and interfacial structure in garnet heterostructures.

cond-mat.mtrl-sci↗

arXiv2025

Enhancement of spin Hall angle by an order of magnitude via Cu intercalation in MoS$_2$/CoFeB heterostructures

Transition metal dichalcogenides (TMDs) are a novel class of quantum materials with significant potential in spintronics, optoelectronics, valleytronics, and opto-valleytronics. TMDs exhibit strong spin-orbit coupling, enabling efficient spin-charge interconversion, which makes them ideal candidates for spin-orbit torque-driven spintronic devices. In this study, we investigated the spin-to-charge conversion through ferromagnetic resonance in MoS$_2$/Cu/CoFeB heterostructures with varying Cu spacer thicknesses. The conversion efficiency, quantified by the spin Hall angle, was enhanced by an order of magnitude due to Cu intercalation. Magneto-optic Kerr effect microscopy confirmed that Cu did not significantly modify the magnetic domains, indicating its effectiveness in decoupling MoS$_2$ from CoFeB. This decoupling preserves the spin-orbit coupling (SOC) of MoS$_2$ by mitigating the exchange interaction with CoFeB, as proximity to localized magnetization can alter the electronic structure and SOC. First-principles calculations revealed that Cu intercalation notably enhances the spin Berry curvature and spin Hall conductivity, contributing to the increased spin Hall angle. This study demonstrates that interface engineering of ferromagnet/TMD-based heterostructures can achieve higher spin-to-charge conversion efficiencies, paving the way for advancements in spintronic applications.

cond-mat.mtrl-sci↗

arXiv2024

Efficient spin to charge conversion and spin memory loss mitigation in oriented $\text{RuO}_2$ films

$\text{RuO}_2$, a transition metal oxide, is attracting attention in spintronics for its unique altermagnetic properties, which influence spin currents. Its ability to produce large spin-orbit torques and spin Hall effects is key for energy-efficient magnetic memory and logic devices. Additionally, the tunable thickness and crystallinity of $\text{RuO}_2$ thin films optimize torque efficiency for low-power switching. Spin pumping, a versatile method for investigating spin dynamics in $\text{RuO}_2$ thin films, has garnered considerable interest because of its straightforward, non-invasive and uncomplicated approach to addressing impedance mismatch and direct measurement of spintronic parameters. Here we present a systematic and detailed analysis on the efficient spin to charge conversion in (110)-oriented $\text{RuO}_2$ films with amorphous CoFeB as spin source. The spin Hall angle, and spin diffusion length were estimated to be 0.14 $\pm$ 0.01 and 4.58 $\pm$ 0.40 nm, respectively. The spin Hall conductivity of 998.89 $\pm$ 58.23 $\hbar \cdot \frac{Ω^{-1} \, \text{cm}^{-1}}{e}$ has been estimated which is theoretically predicted to be of the similar order. The interfacial spin transparency has been achieved to be 90%. We have shown that the spin memory loss at the $\text{RuO}_2$/CoFeB interface is 15%, which is very small.

cond-mat.mtrl-sci↗

arXiv2024

Magnon mediated spin pumping by coupled ferrimagnetic garnets heterostructure

Spin pumping has significant implications for spintronics, providing a mechanism to manipulate and transport spins for information processing. Understanding and harnessing spin currents through spin pumping is critical for the development of efficient spintronic devices. The use of a magnetic insulator with low damping, enhances the signal-to-noise ratio in crucial experiments such as spin-torque ferromagnetic resonance (FMR) and spin pumping. A magnetic insulator coupled with a heavy metal or quantum material offers a more straight forward model system, especially when investigating spin-charge interconversion processes to greater accuracy. This simplicity arises from the absence of unwanted effects caused by conduction electrons unlike in ferromagnetic metals. Here, we investigate the spin pumping in coupled ferrimagnetic (FiM) Y3Fe5O12 (YIG)/Tm3Fe5O12 (TmIG) bilayers combined with heavy-metal (Pt) using the inverse spin Hall effect (ISHE). It is observed that magnon transmission occurs at both of the FiMs FMR positions. The enhancement of spin pumping voltage (Vsp) in the FiM garnet heterostructures is attributed to the strong interfacial exchange coupling between FiMs. The modulation of Vsp is achieved by tuning the bilayer structure. Further, the spin mixing conductance for these coupled systems is found to be 10^18 m^-2. Our findings describe a novel coupled FiM system for the investigation of magnon coupling providing new prospects for magnonic devices.

cond-mat.mtrl-sci↗