arXiv subjects

Laxmipriya Nanda

Publications and source records attributed to Laxmipriya Nanda.

6 recordsLinked to original sources

arXiv2026

Berry Curvature Driven Transport in Silicon-Compatible Altermagnetic $α$-MnTe Thin Films

Integrating spin-dependent functionality with mainstream semiconductor technology is a central goal of modern spintronics, yet most candidate materials remain incompatible with silicon-based platforms. Here, we report the direct epitaxial integration of $α$-MnTe thin films on Si(111) via molecular beam epitaxy and demonstrate a robust anomalous Hall effect (AHE) in this silicon-compatible altermagnetic system. Despite the absence of net bulk magnetization, the films exhibit a pronounced hysteretic Hall response, providing transport evidence consistent with finite Berry curvature generated by symmetry breaking in the thin-film geometry. High-resolution structural and spectroscopic characterization confirms phase-pure, epitaxial growth with hexagonal NiAs-type symmetry, while magnetotransport measurements reveal correlated hysteresis in both transverse and longitudinal channels with systematic temperature evolution. First-principles calculations reveal substantial uncompensated Berry curvature arising from the spin-split band structure, consistent with altermagnetic symmetry and the origin of the observed Hall response. These results establish MnTe/Si(111) as a silicon-compatible altermagnetic platform and chart a concrete pathway for embedding Berry-phase-driven functionalities into scalable semiconductor device architectures.

cond-mat.mtrl-sci↗

arXiv2026

Barium Hexaferrite Thin Films as a Scalable Magnetic-Insulator Platform for Proximity-Engineered Spintronics

Rare-earth iron garnets, such as yttrium iron garnet (YIG) and thulium iron garnet (TmIG), are the benchmark magnetic insulators for spintronic and magnonic devices, but achieving usable perpendicular magnetic anisotropy (PMA) in these materials typically relies on substrate strain- engineering, requiring careful lattice-matching and specific growth conditions that constrain ma- terial accessibility. Here we establish sputter grown barium hexaferrite (BaFe12O19, BaM) as a magnetic-insulator alternative with strong intrinsic perpendicular anisotropy, requiring no strain engineering. X-ray diffraction, transmission electron microscopy and Raman spectroscopy confirm stoichiometric films with atomically smooth surfaces, while first-principles calculations corroborate a robust ferrimagnetic ground state. The films exhibit square out-of-plane hysteresis with a coercive field of nearly 0.1 T. Unlike rare-earth garnets, the perpendicular anisotropy in BaM is intrinsic to its magnetoplumbite crystal structure, arising independent of highly ordered strain. Interfaced with Pt and with exfoliated BiSbTeSe2 (BSTS), BaM induces proximity induced anomalous Hall trans- port, confirming efficient interfacial exchange coupling, while the BSTS/BaM heterostructure shows an additional Hall contribution suggestive of non-collinear interfacial spin textures. These results position BaM thin films as a scalable magnetic-insulator platform for spintronic and topological heterostructure devices beyond the constraints of garnet chemistry.

cond-mat.mtrl-sci↗

arXiv2026

Vortex Transport in Ni/Bi Bilayer Superconductor with Strong Spin-Orbit and Exchange Interaction

Nickel/bismuth (Ni/Bi) bilayers are a promising platform for exploring unconventional superconductivity. Ferromagnetic Ni is coupled to Bi, a strong spin orbit metal that only becomes superconducting below approx 10 mK, forming a bilayer exhibits superconductivity at a much higher temperatures, a Tc of 3 to 4 K. Such a bilayer thus makes an ideal system to probe Cooper pairing in strong spin orbit coupled magnetic environments. Magneto transport studies near Tc reveal the behavior of vortex dynamics and exchange proximity effects. It is seen that isolated vortices of the bilayers respond sensitively to out of plane fields, producing antisymmetric transverse resistance peaks attributable to competing Magnus and viscous forces. Control experiments using a ferromagnetic insulator confirm that superconductivity extends throughout the bilayer, not just confined at the interface. Overall, the results provide a unified picture of transport dominated by vortex dynamics and show that a conventional s wave order parameter accounts for the observations, with any likely unconventional contributions being only subtle.

cond-mat.supr-con↗

arXiv2023

Bismuth Phase Dependent Growth of Superconducting NiBi3 Nanorods

We report a study on the growth of NiBi3 nanowires and nanorods during the preparation of superconducting NiBi3 films by co-evaporation of Ni and Bi. We find that NiBi3 films grown via co-evaporation of Ni and Bi metals achieve higher transition temperatures (4.4 K) compared even to the single crystal NiBi3. However, in certain parameter space, the film surfaces were spattered with nanoscale features, such as nanowires and nanorods. Ambient temperature deposition resulted in polycrystalline NiBi3 nanorods which were controllable with the evaporation rate of Bi. Deposition at elevated temperatures promoted the emergence of long single crystalline NiBi3 nanorods. High resolution transmission electron microscopy measurements confirmed the crystalline behaviour of the nanorods. We believe that NiBi3 nanowires form in a process analogous to the well known vapor-liquid-solid process, as we observe an amorphous Bi cap on the nanorods. From glancing angle X-ray diffraction measurements we identify that the presence of trigonal Bi with hexagonal primitive cell in the film promotes the nucleation of nanorods. Electrical transport on a single NiBi3 nanowire shows a superconducting transition of 4.3K.

cond-mat.supr-con↗

arXiv2023

Josephson coupling driven magnetoresistance in superconducting NiBi3 nanowires

We present results of magnetoresistance (MR) measurements in granular NiBi3 nanowires in the resistive state below the superconducting transition temperature. MR of 100 nm wide nanowires fabricated by focused Ion beam lithography from granular films of NiBi3 with and without magnetic Ni impurity were compared. The nanowire containing high concentration of Ni impurity showed oscillations in MR and also exhibited a negative MR in certain temperature and field range. None of these effects were observed in the nanowire with no Ni impurities. Therefore, we argue that this effect is a result of the random Josephson couplings realized across superconducting NiBi3 grains via magnetic inter grain regions. Such random couplings can cause local fluctuations in the density and sign of supercurrent, which can lead to negative MR and oscillations in MR, as proposed by Kivelson & Spivak [Kivelson et al. Phy. Rev. B. 45, 10490 (1992)].

cond-mat.supr-con↗

arXiv2022

Defect Controlled Ferromagnetic Ordering in Au Implanted TiSe$_2$ Nanocrystals

Layered transition metal dichalcogenides (TMDs) are attracting increasing attention because they exhibit unconventional magnetic properties due to crystal imperfections in their usually non-magnetic 2D structure. This work aims to investigate the magnetic response of self-engineered Se deficient TiSe$_2$ thin films, synthesized using chemical vapour deposition. We demonstrate tunability of the ferromagnetic order with the introduction of Au atoms using low energy Au ion implantation, which works as a controlling knob to vary the stoichiometry of Se in TiSe$_{2-x}$. The corresponding isothermal field-magnetization curves fit well with a modified Brillouin J function with J value of 1.5 for Ti$^{3+}$, and 4 for Au$^{3+}$, accounting for the diamagnetism that arises from Au implantation. We propose a qualitative model for the experimentally observed magnetization as a function of ion fluence, corroborated with high-resolution transmission electron microscopy. Depending on the Au nanoparticle size in the implanted samples, magnetization saturates faster at a much lower applied magnetic field than the pristine sample. Our findings hold potential to expand the range of 2D ferromagnetic materials for spintronics and magnetic sensing applications.

cond-mat.mes-hall↗