Bikash Das

• Master of Science
• Research Scholar at Indian Association for the Cultivation of Science

We report a sequential two-step vapor deposition process for growing mixed-dimensional vdW materials, specifically Te nanowires (1D) and MoS2 (2D), on a single SiO2 wafer. Our growth technique offers a unique potential pathway to create large-scale, high-quality, defect-free interfaces. The assembled samples serve a twofold purpose: first, the as-p...

The interaction of ultrasonic waves with piezoelectric materials provides a quantitative route to enhance electrical and mechanical coupling in van der Waals (vdW) heterostructures. Here, wire‐bonding tip‐assisted ultrasound (≈100 kHz) is presented as an effective approach to achieve piezoelectric transduction in monolayer MoS2 on Si/SiO2 substrate...

Magnons — wavelike spin excitations in magnets — transfer energy and information without moving charge, like ripples on water. Here, in FePS3, an antiferromagnetic insulator, magnons interact with the electrons of few-layer graphene when in a heterostructure, enabling spin waves to convert into electrical signals. In FePS3, magnons soften below 40...

Magnetodielectric (MD) materials are important for their ability to spin-charge conversion, magnetic field control of electric polarization and vice versa. Among these, two-dimensional (2D) van der Waals (vdW) magnetic materials are of particular interest due to the presence of magnetic anisotropy (MA) originating from the interaction between the m...

Magnetodielectric (MD) materials are important for their ability to spin-charge conversion, magnetic field control of electric polarization and vice versa. Among these, two-dimensional (2D) van der Waals (vdW) magnetic materials are of particular interest due to the presence of magnetic anisotropy (MA) originating from the interaction between the m...

We report a sequential two-step vapor deposition process for growing mixed-dimensional van der Waals (vdW) materials, specifically Te nanowires (1D) and MoS$_2$ (2D), on a single SiO$_2$ wafer. Our growth technique offers a unique potential pathway to create large scale, high-quality, defect-free interfaces. The assembly of samples serves a twofold...

Electron-magnon coupling reveals key insights into the interfacial properties between non-magnetic metals and magnetic insulators, influencing charge transport and spin dynamics. Here, we present temperature-dependent Raman spectroscopy and magneto-transport measurements of few-layer graphene (FLG)/antiferromagnetic FePS\(_3\) heterostructures. The...

In two-dimensional van der Waals (vdW) layered materials, application of pressure often induces a giant lattice collapse, which can subsequently drive an associated Mott transition. Here, we investigate room-temperature layer-dependent insulator-metal transition (IMT) and probable spin-crossover in vdW magnet, FePS3, under high-pressure using micro...

Two-dimensional (2D) van der Waals (vdW) materials with lower symmetry (triclinic, monoclinic or orthorhombic) exhibit intrinsic anisotropic in-plane structure desirable for future optoelectronic surface operating devices. Herein, we report one such material, 2D $p$-type semiconductor germanium sulfide (GeS), a group IV monochalcogenide with pucker...

Induced magnetic order in a topological insulator (TI) can be realized either by depositing magnetic adatoms on the surface of a TI or engineering the interface with epitaxial thin film or stacked assembly of 2D van der Waals (vdW) materials. Herein, the observation of spin‐phonon coupling in the otherwise non‐magnetic TI Bi2Te3 is reported, due to...

We investigate thickness-dependent transformation from the paramagnetic to the ferromagnetic phase in Cr2Ge2Te6 (CGT) in bulk and few-layer flake forms. Two-dimensional (2D) Ising-like critical transition in bulk CGT occurs at Tc=67 K with out-of-plane magnetic anisotropy. Few-layer CGT on hBN/SiO2/Si substrate displays the same Tc but also exhibit...

Ferroelectric negative capacitance field-effect transistors, or FE-NCFETs, are promising device architectures for achieving improved performance in terms of hysteresis, on−off ratio, and power consumption. The study investigates the influence of negative capacitance (NC) on the transfer characteristics of van der Waals field-effect transistors belo...

Ferroelectric negative capacitance transistors, or Fe-NCFETs, are promising device architecture for achieving improved performance in terms of hysteresis, on-off ratio and power consumption. The study investigates the influence of negetive capacitance (NC) on the transfer characteristics of van der Waals Field-Effect Transistors (vdW FETs) below an...

We report anisotropic magnetodielectric coupling in layered van der Waals antiferromagnetic FePS3 (Néel temperature TN∼ 120 K) with perpendicular anisotropy. Above TN, while the dielectric response function along the c axis shows frequency-dependent relaxations, in-plane data is frequency independent and reveals a deviation from phonon-anharmonicit...

One-dimensional (1D) van der Waals (vdW) materials offer nearly defect-free strands as channel materials in the field-effect transistor devices and probably, a better interconnect than conventional copper with higher current density and resistance to electro-migration with sustainable down-scaling. We report a theoretically predicted halide based 1...

Manipulation of long‐range order in 2D van der Waals (vdW) magnetic materials (e.g., CrI3, CrSiTe3 ,etc.), exfoliated in few‐atomic layer, can be achieved via application of electric field, mechanical‐constraint, interface engineering, or even by chemical substitution/doping. Usually, active surface oxidation due to the exposure in the ambient cond...

Manipulation of long-range order in two-dimensional (2D) van der Waals (vdW) magnetic materials (e.g., CrI$_3$, CrSiTe$_3$ etc.), exfoliated in few-atomic layer, can be achieved via application of electric field, mechanical-constraint, interface engineering, or even by chemical substitution/doping. Usually, active surface oxidation due to the expos...

Magnetic insulators in reduced dimension are the ideal model systems to study spin-crossover(SCO) induced cooperative behavior under pressure. Similar to the external perturbations like light illumination or temperature, external pressure may provide new pathway to accelerate giant lattice collapse,and subsequently Mott transition in van der Waals...

Tuning the ambipolar behavior in charge carrier transport via defect-engineering is crucial for achieving high mobility transistors for nonlinear logic circuits. Here, we present the electric-field tunable electron and hole transport in a microchannel device consisting of highly air-stable van der Waals (vdW) noble metal dichalcogenide (NMDC), PdSe...

Induced magnetic order in a topological insulator (TI) can be realized either by depositing magnetic adatoms on the surface of a TI or engineering the interface with epitaxial thin film or stacked assembly of two-dimensional (2D) van der Waals (vdW) materials. Herein, we report the observation of spin-phonon coupling in the otherwise non-magnetic T...

We report on the anisotropic magnetic properties of two‐dimensional van der Waals (vdW) insulator, chromium oxychloride (CrOCl). Temperature‐dependent bulk magnetization reveals a paramagnetic to antiferromagnetic phase transition at ∽ 14 K (Néel temperature, TN) while cooling. From the magnetic field dependent magnetization study (M‐H) at low‐temp...

Conductive atomic force microscopy (cAFM) reveals the emergence of conducting states in MoTe2 NFs under applied electric field. In this report, we explore the use of electric field induced conducting states in the single-crystalline MoTe2 nanoflakes (NFs) for nonvolatile resistive memory technologies. The memristive devices are fabricated in vertic...

One-dimensional (1D) van der Waals (vdW) materials offers nearly defect-free strands as channel material in the field-effect transistor (FET) devices and probably, a better interconnect than conventional copper with higher current density and resistance to electro-migration with sustainable down-scaling. We report a new halide based "truly" 1D few-...

We apply periodic control to realize a quantum thermal transistor, which we term as the Floquet quantum thermal transistor. Periodic modulation allows us to control the heat flows and achieve large amplification factors even for fixed bath temperatures. Importantly, this transistor effect persists in the cutoff region, where traditional quantum the...

We report anisotropic magnetodielectric (MD) coupling in layered van der Waals (vdW) antiferromagnetic (AFM) FePS$_3$ (N\'eel temperature $T_{\mathrm{N}}$ $\sim$ 120K) with perpendicular anisotropy. Above $T_{\mathrm{N}}$, while dielectric response function along $c$-axis shows frequency dependent relaxations, in-plane data is frequency independent...

We apply periodic control to realize a quantum thermal transistor, which we term as the Floquet Quantum thermal Transistor. Periodic modulation allows us to control the heat flows and achieve large amplification factors even for fixed bath temperatures. Importantly, this transistor effect persists in the cut-off region, where traditional quantum th...

Electron transport through a nanostructure in source-drain geometry depends on quantum confinement and quality of metal contacts. In addition, transport mechanism varies with the alignment of the nanostructure between the contacts. For potential applications, thorough understanding of the electrical transport of a single nano object having various...

Exploiting supramolecular synthon approach based on a Cambridge Structural Database (CSD) analysis, a series of easily accessible primary ammonium sulfonates have been synthesized as potential supramolecular gelators. Single crystal X-ray diffraction (SXRD) structures of majority of the sulfonates reported herein revealed the existence of both 1D a...