Debashis Mondal postdoctoral activity is focused on the electronic structure of topological insulators and related low dimensional materials, such as transition metal (di)chalcogenides, Weyl semimetals etc. The main tools used in his study are ARPES, spin-resolved ARPES and STM techniques.
Electronic structure of the chiral helimagnet and 3d-intercalated transition metal dichalcogenide Cr1/3NbS2
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
The electronic structure of the chiral helimagnet Cr1/3NbS2 has been studied with core level and angle-resolved photoemission spectroscopy (ARPES). Intercalated Cr atoms are found to be effective in donating electrons to the NbS2 layers but also cause significant modifications of the electronic structure of the host NbS2 material. In particular, the data provide evidence that a description of the electronic structure of Cr1/3NbS2 on the basis of a simple rigid band picture is untenable. The data also reveal substantial inconsistencies with the predictions of standard density functional theory. The relevance of these results to the attainment of a correct description of the electronic structure of chiral helimagnets, magnetic thin films/multilayers, and transition metal dichalcogenides intercalated with 3d magnetic elements is discussed.
From our users
Phys. Rev. B, 100, 195134, (2019)
Observation of bulk states and spin-polarized topological surface states in transitionmetal dichalcogenide Dirac semimetal candidate NiTe2
B. Ghosh, D. Mondal, C.-N. Kuo, C.S. Lue, J. Nayak, J. Fujii, I. Vobornik, A. Politano, and A. Agarwal
We predict NiTe2 to be a type-II Dirac semimetal based on ab initio calculations and explore its bulk and spin-polarized surface states using spin- and angle-resolved photoemission spectroscopy (spin-ARPES). Our results show that, unlike PtTe2, PtSe2, and PdTe2, the Dirac node in NiTe2 is located in close vicinity to 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, infrared plasmonics, and ultrafast optoelectronics.
From our users
Phys. Rev. B, 100, 121104, (2019)
Surface states and Rashba-type spin polarization in antiferromagnetic MnBi2Te4(0001)
R.C. Vidal, H. Bentmann, T.R.F. Peixoto, A. Zeugner, S. Moser, C.-H. Min, S. Schatz, K. Kißner, M. Ünzelmann, C.I. Fornari, H.B. Vasili, M. Valvidares, K. Sakamoto, D. Mondal, J. Fujii, I. Vobornik, S. Jung, C. Cacho, T.K. Kim, R.J. Koch, C. Jozwiak, A. Bostwick, J.D. Denlinger, E. Rotenberg, J. Buck, M. Hoesch, F. Diekmann, S. Rohlf, M. Kalläne, K. Rossnagel, M.M. Otrokov, E.V. Chulkov, M. Ruck, A. Isaeva, and F. Reinert
The layered van der Waals antiferromagnet MnBi2Te4 has been predicted to combine the band ordering of archetypical topological insulators such as Bi2Te3 with the magnetism of Mn, making this material a viable candidate for the realization of various magnetic topological states. We have systematically investigated the surface electronic structure of MnBi2Te4(0001) single crystals by use of spin- and angle-resolved photoelectron spectroscopy experiments. In line with theoretical predictions, the results reveal a surface state in the bulk band gap and they provide evidence for the influence of exchange interaction and spin-orbit coupling on the surface electronic structure.
Strada Statale 14 - km 163,5 - 34149 Trieste, ITALY
ph. +39 040 3756487 fax +39 040 226767
NFFA is a Progetto Internazionale financed by MIUR through CNR
(Istituto Officina dei Materiali, Trieste) and Elettra-Sincrotrone Trieste
and managed by the Commissione NFFA chaired by Giorgio Rossi
(Università di Milano and IOM-CNR).