Papers by Debashis Mondal 142-15-3709
Cornell University - arXiv, May 25, 2022
The Journal of Physical Chemistry C, 2021
Advanced Quantum Technologies, 2021
Advanced Quantum Technologies, 2021
The ZrSiS family of compounds hosts various exotic quantum phenomena due to the presence of both ... more The ZrSiS family of compounds hosts various exotic quantum phenomena due to the presence of both topological nonsymmorphic Dirac fermions and nodal-line fermions. In this material family, the LnSbTe (Ln= lanthanide) compounds are particularly interesting owing to the intrinsic magnetism from magnetic Ln which leads to new properties and quantum states. In this work, the authors focus on the previously unexplored compound SmSbTe. The studies reveal a rare combination of a few functional properties in this material, including antiferromagnetism with possible magnetic frustration, electron correlation enhancement, and Dirac nodal-line fermions. These properties enable SmSbTe as a unique platform to explore exotic quantum phenomena and advanced functionalities arising from the interplay between magnetism, topology, and electronic correlations.
Nature Communications, 2021
The advent of topological semimetals enables the exploitation of symmetry-protected topological p... more The advent of topological semimetals enables the exploitation of symmetry-protected topological phenomena and quantized transport. Here, we present homogeneous rectifiers, converting high-frequency electromagnetic energy into direct current, based on low-energy Dirac fermions of topological semimetal-NiTe2, with state-of-the-art efficiency already in the first implementation. Explicitly, these devices display room-temperature photosensitivity as high as 251 mA W−1 at 0.3 THz in an unbiased mode, with a photocurrent anisotropy ratio of 22, originating from the interplay between the spin-polarized surface and bulk states. Device performances in terms of broadband operation, high dynamic range, as well as their high sensitivity, validate the immense potential and unique advantages associated to the control of nonequilibrium gapless topological states via built-in electric field, electromagnetic polarization and symmetry breaking in topological semimetals. These findings pave the way fo...
ACS Nano, 2021
Due to their peculiar quasiparticle excitations, topological metals have high potential for appli... more Due to their peculiar quasiparticle excitations, topological metals have high potential for applications in the fields of spintronics, catalysis, and superconductivity. Here, by combining spin-and angle-resolved photoemission spectroscopy, scanning tunneling microscopy/spectroscopy, and density functional theory, we discover surface-termination-dependent topological electronic states in the recently discovered mitrofanovite Pt 3 Te 4. Mitrofanovite crystal is formed by alternating, van der Waals bound layers of Pt 2 Te 2 and PtTe 2. Our results demonstrate that mitrofanovite is a topological metal with terminationdependent (i) electronic band structure and (ii) spin texture. Despite their distinct electronic character, both surface terminations are characterized by electronic states exhibiting strong spin polarization with a node at the Γ point and sign reversal across the Γ point, indicating their topological nature and the possibility of realizing two distinct electronic configurations (both of them with topological features) on the surface of the same material.
Advanced Functional Materials, 2021
The emergence of Dirac semimetals has stimulated growing attention, owing to the considerable tec... more The emergence of Dirac semimetals has stimulated growing attention, owing to the considerable technological potential arising from their peculiar exotic quantum transport related to their nontrivial topological states. Especially, materials showing type‐II Dirac fermions afford novel device functionalities enabled by anisotropic optical and magnetotransport properties. Nevertheless, real technological implementation has remained elusive so far. Definitely, in most Dirac semimetals, the Dirac point lies deep below the Fermi level, limiting technological exploitation. Here, it is shown that kitkaite (NiTeSe) represents an ideal platform for type‐II Dirac fermiology based on spin‐resolved angle‐resolved photoemission spectroscopy and density functional theory. Precisely, the existence of type‐II bulk Dirac fermions is discovered in NiTeSe around the Fermi level and the presence of topological surface states with strong (≈50%) spin polarization. By means of surface‐science experiments in near‐ambient pressure conditions, chemical inertness towards ambient gases (oxygen and water) is also demonstrated. Correspondingly, NiTeSe‐based devices without encapsulation afford long‐term efficiency, as demonstrated by the direct implementation of a NiTeSe‐based microwave receiver with a room‐temperature photocurrent of 2.8 µA at 28 GHz and more than two orders of magnitude linear dynamic range. The findings are essential to bringing to fruition type‐II Dirac fermions in photonics, spintronics, and optoelectronics.
Advanced Functional Materials, 2020
By means of theory and experiments, the application capability of nickel ditelluride (NiTe 2) tra... more By means of theory and experiments, the application capability of nickel ditelluride (NiTe 2) transition-metal dichalcogenide in catalysis and nanoelectronics is assessed. The Te surface termination forms a TeO 2 skin in an oxygen environment. In ambient atmosphere, passivation is achieved in less than 30 min with the TeO 2 skin having a thickness of about 7 Å. NiTe 2 shows outstanding tolerance to CO exposure and stability in water environment, with subsequent good performance in both hydrogen and oxygen evolution reactions. NiTe 2-based devices consistently demonstrate superb ambient stability over a timescale as long as one month. Specifically, NiTe 2 has been implemented in a device that exhibits both superior performance and environmental stability at frequencies above 40 GHz, with possible applications as a receiver beyond the cutoff frequency of a nanotransistor.
Journal of the Physical Society of Japan, 2020
Chiral crystal YbNi3Ga9 is known as an intermediate valence compound in which a strong hybridizat... more Chiral crystal YbNi3Ga9 is known as an intermediate valence compound in which a strong hybridization between the 4f orbitals and the conduction band is present. The Co-substitution to YbNi3Ga9 work...
Physical Review B, 2019
Using spin-and angle-resolved photoemission spectroscopy (spin-ARPES) together with ab initio cal... more Using spin-and angle-resolved photoemission spectroscopy (spin-ARPES) together with ab initio calculations, we demonstrate the existence of a type-II Dirac semimetal state in NiTe2. We show that, unlike PtTe2, PtSe2, and PdTe2, the Dirac node in NiTe2 is located in close vicinity of the Fermi energy. Additionally, NiTe2 also hosts a pair of band inversions below the Fermi level along the Γ − A high-symmetry direction, with one of them leading to a Dirac cone in the surface states. The bulk Dirac nodes and the ladder of band inversions in NiTe2 support unique topological surface states with chiral spin texture over a wide range of energies. Our work paves the way for the exploitation of the low-energy type-II Dirac fermions in NiTe2 in the fields of spintronics, THz plasmonics and ultrafast optoelectronics.
Scientific Reports, 2018
Earthquakes are part of a cycle of tectonic stress buildup and release. As fault zones near the e... more Earthquakes are part of a cycle of tectonic stress buildup and release. As fault zones near the end of this seismic cycle, tipping points may be reached whereby triggering occurs and small forces result in cascading failures. The extent of this effect on global seismicity is currently unknown. Here we present evidence of ongoing triggering of earthquakes at remote distances following large source events. The earthquakes used in this study had magnitudes ≥M5.0 and the time period analyzed following large events spans three days. Earthquake occurrences display increases over baseline rates as a function of arc distance away from the epicenters. The p-values deviate from a uniform distribution, with values for collective features commonly below 0.01. An average global forcing function of increased short term seismic risk is obtained along with an upper bound response. The highest magnitude source events trigger more events, and the average global response indicates initial increased ea...
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Papers by Debashis Mondal 142-15-3709