arXiv subjects

Debashree Nayak

Publications and source records attributed to Debashree Nayak.

5 recordsLinked to original sources

arXiv2026

Interface engineering of spin triplet Cooper pairs for spin-valve implementation

Spin singlet Cooper pairs can be converted into equal-spin triplet pairs at a superconductor/heavy-metal interface under suitable conditions. Under current carrying conditions, these triplet correlations can give rise to a non equilibrium spin moment in the heavy metal through the predicted supercurrent spin-Hall effect. Here we demonstrate that this current induced triplet spin moment, in conjunction with the magnetic moment of a ferromagnetic layer, can enable a magnetic spin-valve response in Nb/Pt/Ni/Pt/Nb vertical nano-devices. The magnitude of this spin-valve effect depends on the efficiency of singlet-triplet Cooper pair conversion at the Nb/Pt interface. In order to facilitate efficient triplet generation, we deliberately introduced interfacial roughness to introduce finite Rashba spin-orbit coupling at the Nb/Pt interface and an out-of-plane component of magnetic moment at the Ni interface. In contrast, no discernible spin-valve response was observed in devices with smooth interfaces within measurement resolutions. Since the magnetic moment of the Ni layer and the current-induced triplet spin moment in the Pt layer are independently switchable using a magnetic field and bias current, respectively, the spin valve can be controlled via either parameters. These results demonstrates a novel approach to directly utilizing the spin polarized triplet Copper pairs in superconducting spintronic applications.

cond-mat.supr-con↗

arXiv2026

Probing Interfacial Magnetic Anisotropy in \texorpdfstring{CoV$_{2}$O$_{4}$}{CoV2O4} using Spin Hall Magnetoresistance

Spin Hall magnetoresistance (SMR) has emerged as a powerful probe for investigating interfacial spin transport and magnetic anisotropy in complex oxide heterostructures. In this work, we investigate the interfacial magnetic anisotropy in Pt/CVO through angle-dependent magnetotransport measurements. Unlike the bulk-sensitive magnetic measurements on both strained CVO and Pt/CVO films, which exhibit a ferrimagnetic transition at $T_{C} \approx 150$ K accompanied by out-of-plane anisotropy that reorients toward in-plane anisotropy below 90 K, SMR reveals a distinct interfacial magnetic anisotropy. The rotational scans of the in-plane transverse SMR at 20 K exhibit substantial hysteresis about [100], while no hysteresis is observed along [110] and [1$\bar{1}$0], indicating a biaxial anisotropy with easy axes along [110] and [1$\bar{1}$0]. Furthermore, the absence of sharp discontinuities in both the in-plane longitudinal and transverse SMR, together with pronounced discontinuities near the in-plane [010] direction during out-of-plane rotation, strongly indicates the presence of in-plane anisotropy. This behavior persists up to 120 K. The discrepancy between the bulk-sensitive magnetic measurements and the SMR response suggests that the Pt/CVO interface retains a magnetic anisotropy distinct from the bulk, highlighting the interfacial sensitivity of SMR. Additionally, the spin mixing conductance is found to be of the order of $10^{14}$ $Ω^{-1}\mathrm{m}^{-2}$, comparable to other oxide-based spintronic systems. These findings highlight the crucial role of interfacial effects in spin transport and establish Pt/CVO as a promising platform for spintronic applications.

cond-mat.str-el↗

arXiv2026

Supercurrent spin Hall effect enabled nanopillar Josephson diodes

In the recent years it has been possible to achieve diode-like, non-reciprocal current-voltage response in Josephson junctions, despite the intrinsic symmetry of the Josephson effect itself. This is typically achieved by incorporating Rashba spin-orbit coupling into the Josephson junction as a strong inversion symmetry breaking component, and external magnetic field as a tuneable time-reversal symmetry breaking component. However, the efficiencies of the external field tuneable Josephson-diodes have remained limited to less than 10 \%, often measured below 100 mK temperature. In this work we take a new approach where non-reciprocity is induced by intrinsic SOC in a heavy metal Josephson barrier via the predicted supercurrent spin-Hall effect. By measuring a series of Nb-Pt-Nb nanopillar junctions we demonstrated field tuneable Josephson diode efficiencies as high as 17\%, measured above liquid Helium temperature. This was possible by the realization of a net non-equilibrium spin segregation in the Pt barrier, due to the supercurrent spin-Hall effect in the Pt barrier, analogous to the normal spin-Hall effect. As the direction of the induced spin moment is determined by the bias current, an external magnetic field causes the associated phases to add with opposite signs for opposite current directions, resulting in a nonreciprocal supercurrent across the junction.

cond-mat.supr-con↗

arXiv2026

Interface and Strain Control of Emergent Weyl Semimetallic Phase in SrNbO$_{3}$/LaFeO$_{3}$ Heterostructures

Realizing correlated topological semimetallic phases in bulk transition-metal oxides remains challenging due to rigid lattice symmetry, correlation-induced gap opening, and limited structural tunability. However, complex-oxide thin films and heterostructures provide a powerful platform to stabilize topological phases by tailoring the requisite lattice symmetry through strain control and interface design. In this study, we demonstrate the emergence of Weyl-like electronic states and associated chiral transport in SrNbO$_3$ (SNO)/LaFeO$_3$ (LFO) bilayers. Transport measurements reveal signatures consistent with nontrivial topology, including large non-saturating MR, a nonlinear Hall response, and a chiral anomaly like feature in longitudinal magnetotransport under parallel electric and magnetic fields ($\mathbf{B} \parallel \mathbf{I}$). In addition, we observe a \textcolor{black}{signature} of anomalous Hall contribution, likely arising from \textcolor{black}{proximity effect induced by LFO layers at the interface}. First-principles calculations reveal an $a^0a^0c^-$ rotation pattern of the NbO$_6$ octahedra, together with interfacial lattice distortions in the SNO layer that drive the emergence of a twofold degenerate Weyl semimetallic phase protected by screw axis lattice symmetry. This is further confirmed by Berry curvature calculations, which show opposite sign Berry curvature peaks for the upper and lower band characteristic of a Weyl node. Our combined experimental and theoretical results highlight the critical role of strain and interfacial octahedral distortions in stabilizing Weyl phase in transition metal based perovskite bilayer.

cond-mat.str-el↗

arXiv2011

A New Proposed Dynamic Quantum with Re-Adjusted Round Robin Scheduling Algorithm and Its Performance Analysis

Scheduling is the central concept used frequently in Operating System. It helps in choosing the processes for execution. Round Robin (RR) is one of the most widely used CPU scheduling algorithm. But, its performance degrades with respect to context switching, which is an overhead and it occurs during each scheduling. Overall performance of the system depends on choice of an optimal time quantum, so that context switching can be reduced. In this paper, we have proposed a new variant of RR scheduling algorithm, known as Dynamic Quantum with Readjusted Round Robin (DQRRR) algorithm. We have experimentally shown that performance of DQRRR is better than RR by reducing number of context switching, average waiting time and average turn around time.

cs.OS↗