Santu Kumar Bera

Quantum oscillation spectroscopy of Fermi-surface topologies in tetralayer graphene

Abhijit Halder, Harsh Varshney, Snehamoyee Hazra, Santu Kumar Bera et autres

Quantum oscillations offer a direct probe of Fermi-surface topology and electronic degeneracy, yet disentangling both simultaneously across the Lifshitz transitions of multiband systems has remained an open experimental challenge. Here, we use Shubnikov-de Haas spectroscopy on a high-mobility, dual-gated Bernal-stacked tetralayer graphene …

Tuning the optical properties of metal halide perovskitenanocrystals by shape engineering

Santu Kumar Bera, Narayan C. Pradhan, K. V. Adarsh

Metal halide perovskites nanocrystals(MHPN), owing to their unique and outstanding photophysical properties, have recently envisioned as promising active materials for wide range of photovoltaic and optoelectronic nanoscale device applications.Several degrees of freedom have been utilized to improve their photophysical properties with increased …

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Exciton many-body interactions and charge transfer in CsPbBr3 /graphene derivatives

Naresh Chandra Maurya, Riyanka Karmakar, Rajesh Kumar Yadav, Pravrati Taank et autres

Charge separation and many-body interactions at the interface of the light-absorbing semiconductor and contact layer are of crucial importance to the photophysical properties and optoelectronic device performance. Here, we report the exciton many-body interactions and charge transfer dynamics at the interface of …

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Facet Engineering for Amplified Spontaneous Emission in Metal Halide Perovskite Nanocrystals

Santu Kumar Bera, Suman Bera, Megha Shrivastava, Narayan C. Pradhan et autres

Auger recombination and thermalization time are detrimental in reducing the gain threshold of optically pumped semiconductor nanocrystal (NC) lasers for future on-chip nanophotonic devices. Here, we report the design strategy of facet engineering to reduce the gain threshold of amplified spontaneous emission …

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Correction to Room-Temperature Anomalous Coherent Excitonic Optical Stark Effect in Metal Halide Perovskite Quantum Dots

Megha Shrivastava, Franziska Krieg, Dipendranath Mandal, Ajay K. Poonia et autres

ADVERTISEMENT RETURN TO ISSUEPREVAddition/CorrectionNEXTORIGINAL ARTICLEThis notice is a correctionCorrection to Room-Temperature Anomalous Coherent Excitonic Optical Stark Effect in Metal Halide Perovskite Quantum DotsMegha ShrivastavaMegha ShrivastavaMore by Megha Shrivastava, Franziska KriegFranziska KriegMore by Franziska Krieg, Dipendranath MandalDipendranath MandalMore by Dipendranath Mandalhttps://orcid.org/0000-0003-1872-2792, Ajay K. …

Room-Temperature Anomalous Coherent Excitonic Optical Stark Effect in Metal Halide Perovskite Quantum Dots

Megha Shrivastava, Franziska Krieg, Dipendranath Mandal, Ajay K. Poonia et autres

Nonresonant optical driving of confined semiconductors can open up exciting opportunities for experimentally realizing strongly interacting photon-dressed (Floquet) states through the optical Stark effect (OSE) for coherent modulation of the exciton state. Here we report the first room-temperature observation of the Floquet …

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Shape Engineered Ultrafast Carrier Dynamics in Lead Halide Perovskite Nanocrystals

Santu Kumar Bera, Suman Bera, Narayan C. Pradhan, K. V. Adarsh

We demonstrate dynamical photo-physics of shape-engineered cube (6 facets), rhombic-dodecahedron (12 facets), and rhombicuboctahedron (26 facets) CsPbBr3 nanocrystals using ultrafast pump-probe spectroscopy. Results show remarkably contrasting carrier dynamics and Burstein-Moss effect for tuning optoelectronic properties.

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Atomlike interaction and optically tunable giant band-gap renormalization in large-area atomically thin MoS 2

Santu Kumar Bera, Megha Shrivastava, Bramhachari Khamari, Hanyu Zhang et autres

Coulomb interactions in atomically thin transition metal dichalcogenides can be dynamically engineered by exploiting the dielectric environment to control the optical and electronic properties. Here we demonstrate an optically tunable giant band-gap renormalization (BGR) $\ensuremath{\sim}1200$ and 850 meV from the edge of …

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Layer Degree of Freedom for Ultrafast Exciton Dynamics in Transition Metal Dichalcogenides

Santu Kumar Bera, Megha Shrivastava, Hanyu Zhang, Elisa M. Miller et autres

We demonstrate layer-engineered crossover of relaxation pathways from fast exciton- exciton annihilation in monolayer to slow phonon bottleneck in few-layer MoS2. Our study reveals new, layer degree of freedom to tune ultrafast dynamics in optoelectronic applications.

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Engineering exciton many-body interaction in atomically thin MoS2

Santu Kumar Bera, Dipendranath Mandal, K. V. Adarsh

Atomically thin transition metal dichalcogenides (TMDCs) have emerged as a leading semiconductor over the past decades due to their exceptional electronic, optoelectronic and quantum properties. Here, we have studied tuning of optical and electronic properties in CVD grown single- and few-layer MoS2 …

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Ultrafast direct charge transfers mediated modification of third order nonlinear optical response in Sb2Se3–Au core shell nanorods

Rajesh Kumar Yadav, J. Aneesh, Rituraj Sharma, Santu Kumar Bera et autres

Realization of the direct charge transfer at metal–semiconductor interfaces is a long-standing goal of both fundamental and technological significance. Here we report the synthesis of a colloidal Sb2Se3–Au core–shell nanorod as a model system to demonstrate an efficient direct charge transfer from …

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Intensity mediated change in the sign of ultrafast third-order nonlinear optical response in As2S2 thin films

Dipendranath Mandal, Rajesh Kumar Yadav, Anirban Mondal, Santu Kumar Bera et autres

We study experimentally and theoretically the intensity-dependent off-resonant ultrafast third-order nonlinear optical response of As2S2 thin films. At low intensity, we observed saturable absorption with a negative (self-defocusing) nonlinear refractive index (n2) which at higher intensity switched over to reverse saturable absorption …

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