Publications

2021

1. A New Spin-Correlated Plasmon in Novel Highly Oriented Single-Crystalline Gold Quantum Dots Bin Leong Ong, Muhammad Avicenna Naradipa, Angga Dito Fauzi, Muhammad Aziz Majidi, Caozheng Diao, Satoshi Kurumi, Pranab Kumar Das, Chi Xiao, Ping Yang, Mark B. H. Breese, Sheau Wei Ong, Khay Ming Tan, Eng Soon Tok, and Andrivo Rusydi Nano Letters 21, 7448 (2021).  Abstract   Link   PDF

   A concept of spin plasmon, a collective mode of spin-density, in strongly correlated electron systems has been proposed since the 1930s. It is expected to bridge between spintronics and plasmonics by strongly confining the photon energy in the subwavelength scale within single magnetic-domain to enable further miniaturizing devices. However, spin plasmon in strongly correlated electron systems is yet to be realized. Herein, we present a new spin correlated-plasmon at room temperature in novel Mott-like insulating highly oriented single-crystalline gold quantum-dots (HOSG-QDs). Interestingly, the spin correlated-plasmon is tunable from the infrared to visible, accompanied by spectral weight transfer yielding a large quantum absorption midgap state, disappearance of low-energy Drude response, and transparency. Supported with theoretical calculations, it occurs due to an interplay of surprisingly strong electron-electron correlations, s-p hybridization and quantum confinement in the s band. The first demonstration of the high sensitivity of spin correlated-plasmon in surface-enhanced Raman spectroscopy is also presented.

2. Moving Dirac nodes by chemical substitution Niloufar Nilforoushan, Michele Casula, Adriano Amaricci, Marco Caputo, Jonathan Caillaux, Lama Khalil, Evangelos Papalazarou, Pascal Simon, Luca Perfetti, Ivana Vobornik, Pranab Kumar Das, Jun Fujii, Alexei Barinov, David Santos-Cottin, Yannick Klein, Michele Fabrizio, Andrea Gauzzi, and Marino Marsi PNAS 118, e2108617118 (2021).  Abstract   Link   PDF

   The on-demand control of topological properties with readily modifiable parameters is a fundamental step toward the design of novel electronic and spintronic devices. Here, we show that this goal can be achieved in the correlated system BaCo_1-xNi_xS₂, where we succeeded in significantly changing the reciprocal space position and shape of Dirac nodes by chemically substituting Ni with Co. We prove that the tunability of the Dirac states is realized by varying the electron-correlation strength and the charge-transfer gap, both sensitive to the substitution level, x. Based on our finding, a class of late-transition metal compounds can be established as prototypical for engineering highly tunable Dirac materials. Dirac fermions play a central role in the study of topological phases, for they can generate a variety of exotic states, such as Weyl semimetals and topological insulators. The control and manipulation of Dirac fermions constitute a fundamental step toward the realization of novel concepts of electronic devices and quantum computation. By means of Angle-Resolved Photo-Emission Spectroscopy (ARPES) experiments and ab initio simulations, here, we show that Dirac states can be effectively tuned by doping a transition metal sulfide, BaNiS₂, through Co/Ni substitution. The symmetry and chemical characteristics of this material, combined with the modification of the charge-transfer gap of BaCo_1-xNi_xS₂ across its phase diagram, lead to the formation of Dirac lines, whose position in k-space can be displaced along the Γ-M symmetry direction and their form reshaped. Not only does the doping x tailor the location and shape of the Dirac bands, but it also controls the metal-insulator transition in the same compound, making BaCo_1-xNi_xS₂ a model system to functionalize Dirac materials by varying the strength of electron correlations. All study data are included in the article and/or supporting information.

2020

1. Photoinduced metastable dd-exciton-driven metal-insulator transitions in quasi-one-dimensional transition metal oxides Teguh Citra Asmara, Frank Lichtenberg, Florian Biebl, Tao Zhu, Pranab Kumar Das, Muhammad Avicenna Naradipa, Angga Dito Fauzi, Caozheng Diao, Ping Yang, Philipp Lenzen, Sören Buchenau, Benjamin Grimm-Lebsanft, Dongyang Wan, Paolo E. Trevisanutto, Mark B. H. Breese, T. Venkatesan, Michael Rübhausen, and Andrivo Rusydi Communications Physics 3, 206 (2020).  Abstract   Link   PDF

   Photoinduced phase transitions in matters have gained tremendous attention over the past few years. However, their ultrashort lifetime makes their study and possible control very challenging. Here, we report on highly anisotropic d-d excitonic excitations yielding photoinduced metal-insulator transitions (MITs) in quasi-one-dimensional metals Sr_1-yNbO_x using Mueller-Matrix spectroscopic ellipsometry, transient ultraviolet Raman spectroscopy, transient mid-infrared reflectivity and angular-resolved photoemission spectroscopy supported with density functional theory. Interestingly, the MITs are driven by photo-pumping of d-d excitons, causing the metallic a-axis to become insulating while the insulating b- and c-axis concomitantly become a correlated metal. We assign these effects to an interplay between the melting of charge and lattice orderings along the different anisotropic optical axes and Bose-Einstein-like condensation of the photoinduced excitons. The long lifetime in the order of several seconds of the metastable MITs gives greater flexibility to study and manipulate the transient excitonic state for potential applications in exciton-based optoelectronic devices.

2. Giant piezoelectricity in oxide thin films with nanopillar structure Huajun Liu, Haijun Wu, Khuong Phuong Ong, Tiannan Yang, Ping Yang, Pranab Kumar Das, Xiao Chi, Yang Zhang, Caozheng Diao, Wai Kong Alaric Wong, Eh Piew Chew, Yi Fan Chen, Chee Kiang Ivan Tan, Andrivo Rusydi, Mark B. H. Breese, David J. Singh, Long-Qing Chen, Stephen J. Pennycook, and Kui Yao Science 369, 292–297 (2020).  Abstract   Link   PDF

   High-performance piezoelectric materials are critical components for electromechanical sensors and actuators. For more than 60 years, the main strategy for obtaining large piezoelectric response has been to construct multiphase boundaries, where nanoscale domains with local structural and polar heterogeneity are formed, by tuning complex chemical compositions. We used a different strategy to emulate such local heterogeneity by forming nanopillar regions in perovskite oxide thin films. We obtained a giant effective piezoelectric coefficient d_33,f^* of ∼1098 picometers per volt with a high Curie temperature of ∼450 ºC. Our lead-free composition of sodium-deficient sodium niobate contains only three elements (Na, Nb, and O). The formation of local heterogeneity with nanopillars in the perovskite structure could be the basis for a general approach to designing and optimizing various functional materials.

3. Temperature and magnetic field dependent Raman study of electron-phonon interactions in thin films of Bi₂Se₃ and Bi₂Te₃ nanoflakes Sören Buchenau, Sarah Scheitz, Astha Sethi, John E. Slimak, Tomke Eva Glier, Pranab Kumar Das, Torben Dankwort, Lewis Akinsinde, Lorenz Kienle, Andrivo Rusydi, Clemens Ulrich, S. Lance Cooper, and Michael Rübhausen Phys. Rev. B 101, 245431 (2020).  Abstract   Link   PDF

   We have investigated two-dimensional nanostructures of the topological insulators Bi₂Se₃ and Bi₂Te₃ by means of temperature and magnetic field dependent Raman spectroscopy. The surface contribution of our samples was increased by using thin films of dropcasted nanoflakes with the aim of enhancing their topological properties. Raman spectroscopy provides a contact-free method to investigate the behavior of topological properties with temperature and magnetic fields at lower dimensions. The temperature dependent Raman study reveals anharmonic phonon behavior for Bi₂Te₃ indicative of a two-phonon relaxation mechanism in this material. Contrary to this, Bi₂Se₃ shows clear deviations from a two-phonon anharmonic decay model at temperatures below 120 K exhibiting a hardening and broadening, especially of the A²_1g mode. Similarly, the magnetic field dependent self-energy effects are only observed for the A²_1g mode of Bi₂Se₃, showing a broadening and hardening with increasing field. We interpret our results in terms of corrections to the phonon self-energy for Bi₂Se₃ at temperatures below 120 K and magnetic fields above 4 T due to electron-hole pair excitations associated with the conducting surface states. The phonon renormalization with increasing magnetic field is explained by a gap opening in the Dirac cone that enables phonon coupling to the changing electric susceptibility.

4. Correlated plasmons in the topological insulator Bi₂Se₃ induced by long-range electron correlations Thomas J. Whitcher, Mathieu G. Silly, Ming Yang, Pranab Kumar Das, David Peyrot, Xiao Chi, Mahmoud Eddrief, Jisoo Moon, Seongshik Oh, Antonio H. Castro-Neto, Mark B. H. Breese, Andrew T. S. Wee, Fabien Silly, and Andrivo Rusydi NPG Asia Materials 12, 37 (2020).  Abstract   Link   PDF

   Recently, electron correlation has been shown to play an important role in unconventional plasmon generation in highly correlated electron systems. Electrons in topological insulators, on the other hand, are massless and insensitive to nonmagnetic scattering due to their protection by time-reversal symmetry, which makes these materials appealing platforms for hosting exotic plasmonic excitations. Here, using a combination of angle-dependent spectroscopic ellipsometry and angle-resolved photoemission spectroscopy as a function of temperature supported by first-principles calculations, we reveal a new pair of correlated plasmonic excitations at 1.04 and 1.52 eV and a significant Fermi level shift of 0.12 eV accompanied by spectral weight transfer in the topological insulator bismuth selenide (Bi₂Se₃). Interestingly, such a spectral weight transfer over a broad energy range causes a drastic change in the charge carrier density whereby the contribution of charge carriers in the bulk starts to rival those in the surface states and Bi₂Se₃ becomes more uniformly conducting. Our results show the importance of electronic correlations in determining the electronic structure and appearance of correlated plasmons in topological insulators and their potential applications in plasmonics.

5. Optical constants and absorption properties of Te and TeO thin films in the 13-14 nm spectral range Luis V. Rodriguez-de Marcos, Shenbaga M. P. Kalaiselvi, Ong Bin Leong, Pranab K. Das, Mark B. H. Breese, and Andrivo Rusydi Opt. Express 28, 12922–12935 (2020).  Abstract   Link   PDF

   Undesired mask-induced effects caused by thick absorber layers in EUV photomasks reduce the quality of the projected patterns at the wafer stage in EUV photolithography scanners. New materials with better absorption properties than the state-of-the-art absorbers, TaN and TaBN, are required to mitigate these effects. In this work, we investigated the optical properties (δ and k) of Te and TeO films in the 13-14 nm range, and the absorption properties of these two materials at 13.5 nm. δ and k are obtained through fitting experimental values of reflectivity versus angle of incidence in the EUV range. We follow a methodology which combines different characterization techniques (X-ray reflectivity, EUV reflectivity, and X-ray photoemission spectroscopy) to reduce the number of free parameters in models and hence, increase the reliability of the optical constants obtained. At 13.5 nm, we obtain δ = 0.03120, k=0.07338 for Te, and δ = 0.04099, k = 0.06555 for TeO. To experimentally verify the absorption properties of these materials, different thicknesses of Te and TeO films are cast on top of a state-of-the-art mask-quality EUV multilayer with 66.7% reflectivity at 13.5 nm. We found that a reflectivity of ˜0.7% can be attained with either 32.4 nm of Te, or 34.7 nm of TeO, greatly surpassing the absorption properties of TaN and TaBN. The morphology and surface roughness of the Te and TeO films deposited on the multilayer are also investigated.

6. The nature of ferromagnetism in the chiral helimagnet Cr_1/3NbS₂ N. Sirica, P. Vilmercati, F. Bondino, I. Pis, S. Nappini, S.-K. Mo, A. V. Fedorov, P. K. Das, I. Vobornik, J. Fujii, L. Li, D. Sapkota, D. S. Parker, D. G. Mandrus, and N. Mannella Communications Physics 3, 65 (2020).  Abstract   Link   PDF

   The chiral helimagnet Cr_1/3NbS₂ hosts exotic spin textures, whose influence on the magneto-transport properties make this material an ideal candidate for future spintronic applications. To date, the interplay between macroscopic magnetic and transport degrees of freedom is believed to result from a reduction in carrier scattering following spin order. Here, we present electronic structure measurements across the helimagnetic transition temperature T_C that challenges this view. We show that the Fermi surface is comprised of strongly hybridized Nb- and Cr-derived electronic states, and that spectral weight close to the Fermi level increases anomalously as the temperature is lowered below T_C. These findings are rationalized on the basis of first principle density functional theory calculations, which reveal a large nearest-neighbor exchange energy, suggesting the interaction between local spin moments and hybridized Nb- and Cr-derived itinerant states to go beyond the perturbative interaction of Ruderman-Kittel-Kasuya-Yosida, suggesting instead a mechanism rooted in a Hund’s exchange interaction.

7. Distinct behavior of localized and delocalized carriers in anatase TiO₂ (001) during reaction with O₂ Chiara Bigi, Zhenkun Tang, Gian Marco Pierantozzi, Pasquale Orgiani, Pranab Kumar Das, Jun Fujii, Ivana Vobornik, Tommaso Pincelli, Alessandro Troglia, Tien-Lin Lee, Regina Ciancio, Goran Drazic, Alberto Verdini, Anna Regoutz, Phil D. C. King, Deepnarayan Biswas, Giorgio Rossi, Giancarlo Panaccione, and Annabella Selloni Phys. Rev. Materials 4, 025801 (2020).  Abstract   Link   PDF

   Two-dimensional (2D) metallic states induced by oxygen vacancies (VOs) at oxide surfaces and interfaces provide opportunities for the development of advanced applications, but the ability to control the behavior of these states is still limited. We used angle resolved photoelectron spectroscopy combined with density-functional theory (DFT) to study the reactivity of VO-induced states at the (001) surface of anatase TiO₂, where both 2D metallic and deeper lying in-gap states (IGs) are observed. The 2D and IG states exhibit remarkably different evolutions when the surface is exposed to molecular O₂ while IGs are almost completely quenched, the metallic states are only weakly affected. DFT calculations indeed show that the IGs originate from surface VOs and remain localized at the surface, where they can promptly react with O₂. In contrast, the metallic states originate from subsurface vacancies whose migration to the surface for recombination with O₂ is kinetically hindered on anatase TiO₂ (001), thus making them much less sensitive to oxygen dosing.

2019

1. Electronic correlation determining correlated plasmons in Sb-doped Bi₂Se₃ P. K. Das, T. J. Whitcher, M. Yang, X. Chi, Y. P. Feng, W. Lin, J. S. Chen, I. Vobornik, J. Fujii, K. A. Kokh, O. E. Tereshchenko, C. Z. Diao, Jisoo Moon, Seongshik Oh, A. H. Castro-Neto, M. B. H. Breese, A. T. S. Wee, and A. Rusydi Phys. Rev. B 100, 115109 (2019).  Abstract   Link   PDF

   Electronic correlation is believed to play an important role in exotic phenomena such as insulator-metal transition, colossal magnetoresistance, and high-temperature superconductivity in correlated electron systems. Recently, it has been shown that electronic correlation may also be responsible for the formation of unconventional plasmons. Herewith, using a combination of angle-dependent spectroscopic ellipsometry, angle resolved photoemission spectroscopy, and Hall measurements, all as a function of temperature supported by first-principles calculations, the existence of low-loss high-energy correlated plasmons accompanied by spectral weight transfer, a fingerprint of electronic correlation, in topological insulator (Bi_0.8Sb_0.2)₂Se₃ is revealed. Upon cooling, the density of free charge carriers in the surface states decreases whereas that in the bulk states increases, and the recently reported correlated plasmons are key to explaining this phenomenon. Our result shows the importance of electronic correlation in determining correlated plasmons and opens an alternative path in engineering plasmonic-based topologically insulating devices.

2. Electronic properties of candidate type-II Weyl semimetal WTe₂. A review perspective P K Das, D Di Sante, F Cilento, C Bigi, D Kopic, D Soranzio, A Sterzi, J A Krieger, I Vobornik, J Fujii, T Okuda, V N Strocov, M B H Breese, F Parmigiani, G Rossi, S Picozzi, R Thomale, G Sangiovanni, R J Cava, and G Panaccione Electronic Structure 1, 014003 (2019).  Abstract   Link   PDF

   Currently, there is a flurry of research interest on materials with an unconventional electronic structure, and we have already seen significant progress in their understanding and engineering towards real-life applications. The interest erupted with the discovery of graphene and topological insulators in the previous decade. The electrons in graphene simulate massless Dirac Fermions with a linearly dispersing Dirac cone in their band structure, while in topological insulators, the electronic bands wind non-trivially in momentum space giving rise to gapless surface states and bulk bandgap. Weyl semimetals in condensed matter systems are the latest addition to this growing family of topological materials. Weyl Fermions are known in the context of high energy physics since almost the beginning of quantum mechanics. They apparently violate charge conservation rules, displaying the ’chiral anomaly’, with such remarkable properties recently theoretically predicted and experimentally verified to exist as low energy quasiparticle states in certain condensed matter systems. Not only are these new materials extremely important for our fundamental understanding of quantum phenomena, but also they exhibit completely different transport phenomena. For example, massless Fermions are susceptible to scattering from non-magnetic impurities. Dirac semimetals exhibit non-saturating extremely large magnetoresistance as a consequence of their robust electronic bands being protected by time reversal symmetry. These open up whole new possibilities for materials engineering and applications including quantum computing. In this review, we recapitulate some of the outstanding properties of WTe₂, namely, its non-saturating titanic magnetoresistance due to perfect electron and hole carrier balance up to a very high magnetic field observed for the very first time. It also indicative of hosting Lorentz violating type-II Weyl Fermions in its bandstructure, again first predicted candidate material to host such a remarkable phase. We primarily focus on the findings of our ARPES, spin-ARPES, and time-resolved ARPES studies complemented by first-principles calculations.

3. Electronic structure of the α-(BEDT-TTF)₂I₃ surface by photoelectron spectroscopy Emilie Tisserond, Niloufar Nilforoushan, Marco Caputo, Pere Alemany, Enric Canadell, Lama Khalil, Ivana Vobornik, Jun Fujii, Pranab Kumar Das, Cecile Meziere, Patrick Batail, Jean-Paul Pouget, Claude Pasquier, Marino Marsi, and Miguel Monteverde The European Physical Journal B 92, 70 (2019).  Abstract   Link   PDF

   We report anomalies observed in photoelectron spectroscopy measurements performed on α-(BEDT-TTF)₂I₃ crystals. In particular, above its metal-insulator transition temperature (T = 135 K), we observe the lack of a sharp Fermi edge in contradiction with the metallic transport properties exhibited by this quasi-bidimensional organic material. We interpret these unusual results as a signature of a one-dimensional electronic behavior confirmed by DFT band structure calculations. Using photoelectron spectroscopy we probe a Luttinger liquid with a large correlation parameter (α > 1) that we interpret to be caused by the chain-like electronic structure of α-(BEDT-TTF)₂I₃ surface doped by iodine defects. These new surface effects are inaccessible by bulk sensitive measurements of electronic transport techniques.

2018

1. Band Structure of the IV-VI Black Phosphorus Analog and Thermoelectric SnSe I. Pletikosić, F. Rohr, P. Pervan, P. K Das, I. Vobornik, R. J Cava, and T. Valla Physical Review Letters 120, 156403 (2018).  Link   PDF
2. Epitaxial growth of single-orientation high-quality MoS₂ monolayers Bana Harsh, Travaglia Elisabetta, Bignardi Luca, Lacovig Paolo, E. Sanders Charlotte, Dendzik Maciej, Michiardi Matteo, Bianchi Marco, Lizzit Daniel, Presel Francesco, Angelis Dario De, Apostol Nicoleta, Pranab Kumar Das, Fujii Jun, Ivana Vobornik, Larciprete Rosanna, Baraldi Alessandro, Hofmann Philip, and Lizzit Silvano 2D Materials 5, 035012 (2018).  Abstract   Link   PDF

   We present a study on the growth and characterization of high-quality single-layer MoS₂ with a single orientation, i.e. without the presence of mirror domains. This single orientation of the MoS₂ layer is established by means of x-ray photoelectron diffraction. The high quality is evidenced by combining scanning tunneling microscopy with x-ray photoelectron spectroscopy measurements. Spin- and angle-resolved photoemission experiments performed on the sample revealed complete spin-polarization of the valence band states near the K and -K points of the Brillouin zone. These findings open up the possibility to exploit the spin and valley degrees of freedom for encoding and processing information in devices that are based on epitaxially grown materials.

3. Influence of Spin-Orbit Coupling in Iron-Based Superconductors R. P Day, G. Levy, M. Michiardi, B. Zwartsenberg, M. Zonno, F. Ji, E. Razzoli, F. Boschini, S. Chi, R. Liang, P. K Das, I. Vobornik, J. Fujii, W. N Hardy, D. A Bonn, I. S Elfimov, and A. Damascelli Physical Review Letters 121, 076401 (2018).  Link   PDF
4. Role of spin-orbit coupling in the electronic structure of IrO₂ Pranab Kumar Das, Jagoda Sławińska, Ivana Vobornik, Jun Fujii, Anna Regoutz, Juhan M. Kahk, David O. Scanlon, Benjamin J. Morgan, Cormac McGuinness, Evgeny Plekhanov, Domenico Di Sante, Ying-Sheng Huang, Ruei-San Chen, Giorgio Rossi, Silvia Picozzi, William R. Branford, Giancarlo Panaccione, and David J. Payne Physical Review Materials 2, 065001 (2018).  Link   PDF
5. Switching from Reactant to Substrate Engineering in the Selective Synthesis of Graphene Nanoribbons Néstor Merino-Díez, Jorge Lobo-Checa, Pawel Nita, Aran Garcia-Lekue, Andrea Basagni, Guillaume Vasseur, Federica Tiso, Francesco Sedona, Pranab K. Das, Jun Fujii, Ivana Vobornik, Mauro Sambi, José Ignacio Pascual, J. Enrique Ortega, and Dimas G. Oteyza The Journal of Physical Chemistry Letters 2510-2517 (2018).  Link   PDF
6. Tuning spin-charge interconversion with quantum confinement in ultrathin bismuth films C. Zucchetti, M. T. Dau, F. Bottegoni, C. Vergnaud, T. Guillet, A. Marty, C. Beigné, S. Gambarelli, A. Picone, A. Calloni, G. Bussetti, A. Brambilla, L. Duò, F. Ciccacci, P. K. Das, J. Fujii, I. Vobornik, M. Finazzi, and M. Jamet Physical Review B 98, 184418 (2018).  Link   PDF

2017

1. Compelling experimental evidence of a Dirac cone in the electronic structure of a 2D Silicon layer S. Sadeddine, H. Enriquez, A. Bendounan, P. K. Das, I. Vobornik, A. Kara, A. J. Mayne, F. Sirotti, G. Dujardin, and H. Oughaddou Scientific Reports 7, 44400 (2017).  Link   PDF
2. Giant Rashba effect at the topological surface of PrGe revealing antiferromagnetic spintronics S. Banik, P. K. Das, A. Bendounan, I. Vobornik, A. Arya, N. Beaulieu, J. Fujii, A. Thamizhavel, P. U. Sastry, A. K. Sinha, D. M. Phase, and S. K. Deb Scientific Reports 7, 4120 (2017).  Link   PDF
3. MoTe₂ : An uncompensated semimetal with extremely large magnetoresistance S. Thirupathaiah, R. Jha, B. Pal, J. S. Matias, P. K. Das, P. K. Sivakumar, I. Vobornik, N. C. Plumb, M. Shi, R. A. Ribeiro, and D. D. Sarma Physical Review B 95, 241105 (2017).  Link   PDF
4. Role of Oxygen Deposition Pressure in the Formation of Ti Defect States in TiO₂ (001) Anatase Thin Films B. Gobaut, P. Orgiani, A. Sambri, E. Gennaro, C. Aruta, F. Borgatti, V. Lollobrigida, D. Ceolin, J. P. Rueff, R. Ciancio, C. Bigi, P. K. Das, J. Fujii, D. Krizmancic, P. Torelli, I. Vobornik, G. Rossi, F. M. Granozio, U. S. Uccio, and G. Panaccione Acs Applied Materials & Interfaces 9, 23099-23106 (2017).  Link   PDF
5. Structural and electronic properties of Bi₂Se₃ topological insulator thin films grown by pulsed laser deposition P. Orgiani, C. Bigi, P. K. Das, J. Fujii, R. Ciancio, B. Gobaut, A. Galdi, C. Sacco, L. Maritato, P. Torelli, G. Panaccione, I. Vobornik, and G. Rossi Applied Physics Letters 110, 171601 (2017).  Link   PDF
6. Temperature-independent band structure of WTe₂ as observed from angle-resolved photoemission spectroscopy S. Thirupathaiah, R. Jha, B. Pal, J. S. Matias, P. K. Das, I. Vobornik, R. A. Ribeiro, and D. D. Sarma Physical Review B 96, 165149 (2017).  Link   PDF
7. Three-Dimensional Electronic Structure of the Type-II Weyl Semimetal WTe₂ D. Di Sante, P. K. Das, C. Bigi, Z. Ergonenc, N. Gurtler, J. A. Krieger, T. Schmitt, M. N. Ali, G. Rossi, R. Thomale, C. Franchini, S. Picozzi, J. Fujii, V. N. Strocov, G. Sangiovanni, I. Vobornik, R. J. Cava, and G. Panaccione Physical Review Letters 119, 026403 (2017).  Link   PDF
8. Very efficient spin polarization analysis (VESPA): new exchange scattering-based setup for spin-resolved ARPES at APE-NFFA beamline at Elettra C. Bigi, P. K. Das, D. Benedetti, F. Salvador, D. Krizmancic, R. Sergo, A. Martin, G. Panaccione, G. Rossi, J. Fujii, and I. Vobornik Journal of Synchrotron Radiation 24, 750-756 (2017).  Link   PDF

2016

1. Electronic structure of the chiral helimagnet and 3d-intercalated transition metal dichalcogenide Cr_1/3NbS₂ N. Sirica, S. K. Mo, F. Bondino, I. Pis, S. Nappini, P. Vilmercati, J. Yi, Z. Gai, P. C. Snijders, P. K. Das, I. Vobornik, N. Ghimire, M. R. Koehler, L. Li, D. Sapkota, D. S. Parker, D. G. Mandrus, and N. Mannella Physical Review B 94, 075141 (2016).  Link   PDF
2. Layer-dependent quantum cooperation of electron and hole states in the anomalous semimetal WTe₂ P. K. Das, D. Di Sante, I. Vobornik, J. Fujii, T. Okuda, E. Bruyer, A. Gyenis, B. E. Feldman, J. Tao, R. Ciancio, G. Rossi, M. N. Ali, S. Picozzi, A. Yazdani, G. Panaccione, and R. J. Cava Nature Communications 7, 10847 (2016).  Link   PDF
3. Manipulating the Topological Interface by Molecular Adsorbates: Adsorption of Co-Phthalocyanine on Bi₂Se₃ M. Caputo, M. Panighel, S. Lisi, L. Khalil, G. Di Santo, E. Papalazarou, A. Hruban, M. Konczykowski, L. Krusin-Elbaum, Z. S. Aliev, M. B. Babanly, M. M. Otrokov, A. Politano, E. V. Chulkov, A. Arnau, V. Marinova, P. K. Das, J. Fujii, I. Vobornik, L. Perfetti, A. Mugarza, A. Goldoni, and M. Marsi Nano Letters 16, 3409-3414 (2016).  Link   PDF

2015

1. Crystal growth and magnetic properties of equiatomic CeAl P. K. Das, and A. Thamizhavel In International Conference on Strongly Correlated Electron Systems 2014 592, 012009 (2015).  Link 
2. New Strategy for the Growth of Complex Heterostructures Based on Different 2D Materials Mattia Cattelan, Brian Markman, Giacomo Lucchini, Pranab Kumar Das, Ivana Vobornik, Joshua Alexander Robinson, Stefano Agnoli, and Gaetano Granozzi Chemistry of Materials 27, 4105-4113 (2015).  Link   PDF
3. Signature of Strong Spin-Orbital Coupling in the Large Nonsaturating Magnetoresistance Material WTe₂ J. Jiang, F. Tang, X. C. Pan, H. M. Liu, X. H. Niu, Y. X. Wang, D. F. Xu, H. F. Yang, B. P. Xie, F. Q. Song, P. Dudin, T. K. Kim, M. Hoesch, P. Kumar Das, I. Vobornik, X. G. Wan, and D. L. Feng Physical Review Letters 115, 166601 (2015).  Link   PDF

2014

1. Anisotropic magnetic properties and giant magnetocaloric effect of single- crystal PrSi Pranab Kumar Das, Amitava Bhattacharyya, Ruta Kulkarni, S. K. Dhar, and A. Thamizhavel Physical Review B 89, 134418 (2014).  Link   PDF

2013

1. Magnetic Properties of Single Crystalline CeMg₁₂ Pranab Kumar Das, and A. Thamizhavel In Proceedings of the International Conference on Strongly Correlated Electron Systems 3, 012009 (2013).  Link 

2012

1. Anisotropic magnetic properties and superzone gap formation in CeGe single crystal Pranab Kumar Das, Neeraj Kumar, R. Kulkarni, S. K. Dhar, and A. Thamizhavel Journal of Physics-Condensed Matter 24, 146003 (2012).  Link   PDF
2. Antiferro- and ferromagnetic ordering in a PrGe single crystal Pranab Kumar Das, K. Ramesh Kumar, R. Kulkarni, S. K. Dhar, and A. Thamizhavel Journal of Physics-Condensed Matter 24, 476001 (2012).  Link   PDF
3. Antiferromagnetic ordering in EuPtGe₃ Neeraj Kumar, Pranab Kumar Das, R. Kulkarni, A. Thamizhavel, S. K. Dhar, and P. Bonville Journal of Physics-Condensed Matter 24, 036005 (2012).  Link   PDF
4. Crystal Growth and Magnetic properties of RMg₃ (R = La, Ce and Nd) Pranab Kumar Das, Neeraj Kumar, R. Kulkarni, A. Thamizhavel, SE Sebastian, ML Sutherland, E Pugh, FM Grosche, J Keeling, C Panagopoulos, S Rowley, and SS Saxena In International Conference on Strongly Correlated Electron Systems (Sces 2011) 391, 012009 (2012).  Link 

2011

1. Magnetism in RMg₃ (R = La, Ce and Nd) Single Crystals Pranab Kumar Das, Neeraj Kumar, Ruta Kulkarni, A. Thamizhavel, AB Garg, R Mittal, and R Mukhopadhyay In Solid State Physics: Proceedings of the 55th Dae Solid State Physics Symposium 1349, 1127-1128 (2011).  Link 
2. Magnetic properties of the heavy-fermion antiferromagnet CeMg₃ Pranab Kumar Das, Neeraj Kumar, R. Kulkarni, and A. Thamizhavel Physical Review B 83, 134416 (2011).  Link   PDF