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Canali, Carlo M.
Publications (10 of 89) Show all publications
Han, S. S., Sattar, S., Kireev, D., Shin, J.-C., Bae, T.-S., Ryu, H. I., . . . Jung, Y. (2024). Reversible Transition of Semiconducting PtSe2 and Metallic PtTe2 for Scalable All-2D Edge-Contacted FETs [Letter to the editor]. Nano Letters, 24(6), 1891-1900
Open this publication in new window or tab >>Reversible Transition of Semiconducting PtSe2 and Metallic PtTe2 for Scalable All-2D Edge-Contacted FETs
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2024 (English)In: Nano Letters, ISSN 1530-6984, E-ISSN 1530-6992, Vol. 24, no 6, p. 1891-1900Article in journal, Letter (Refereed) Published
Abstract [en]

Two-dimensional (2D) transition metal dichalcogenide (TMD) layers are highly promising as field-effect transistor (FET) channels in the atomic-scale limit. However, accomplishing this superiority in scaled-up FETs remains challenging due to their van der Waals (vdW) bonding nature with respect to conventional metal electrodes. Herein, we report a scalable approach to fabricate centimeter-scale all-2D FET arrays of platinum diselenide (PtSe2) with in-plane platinum ditelluride (PtTe2) edge contacts, mitigating the aforementioned challenges. We realized a reversible transition between semiconducting PtSe2 and metallic PtTe2 via a low-temperature anion exchange reaction compatible with the back-end-of-line (BEOL) processes. All-2D PtSe2 FETs seamlessly edge-contacted with transited metallic PtTe2 exhibited significant performance improvements compared to those with surface-contacted gold electrodes, e.g., an increase of carrier mobility and on/off ratio by over an order of magnitude, achieving a maximum hole mobility of similar to 50.30 cm(2) V-1 s(-1) at room temperature. This study opens up new opportunities toward atomically thin 2D-TMD-based circuitries with extraordinary functionalities.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2024
Keywords
2D PtTe2 layer, 2D PtSe2 layer, anion exchange, chemical transition, edge contact, 2D TMD heterostructure
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
Physics, Electrotechnology
Identifiers
urn:nbn:se:lnu:diva-127898 (URN)10.1021/acs.nanolett.3c03666 (DOI)001158890700001 ()38150559 (PubMedID)2-s2.0-85183091025 (Scopus ID)
Available from: 2024-02-20 Created: 2024-02-20 Last updated: 2024-03-13Bibliographically approved
Nossa, J., Islam, M. F., Pederson, M. R. & Canali, C. M. (2023). Electric control of spin states in frustrated triangular molecular magnets. Physical Review B, 107(24), Article ID 245402.
Open this publication in new window or tab >>Electric control of spin states in frustrated triangular molecular magnets
2023 (English)In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 107, no 24, article id 245402Article in journal (Refereed) Published
Abstract [en]

Frustrated triangular molecular magnets are a very important class of magnetic molecules since the absence of inversion symmetry allows an external electric field to couple directly with the spin chirality that characterizes their ground state. The spin-electric coupling in these molecular magnets leads to an efficient and fast method of manipulating spin states, making them an exciting candidate for quantum information processing. The efficiency of the spin-electric coupling depends on the spin-induced electric-dipole moment of the frustrated spin configurations contributing to the chiral ground state. In this paper, we report on first-principles calculations of spin-electric coupling in a {V3} triangular magnetic molecule. We have explicitly calculated the spin-induced charge redistribution within the magnetic centers that is responsible for the spin-electric coupling. Furthermore, we have generalized the method of calculating the strength of the spin-electric coupling to calculate any triangular spin-1/2 molecule with C3 symmetry and have applied it to calculate the coupling strength in {V15} molecular magnets.

Place, publisher, year, edition, pages
American Physical Society, 2023
National Category
Condensed Matter Physics
Research subject
Physics, Condensed Matter Physics
Identifiers
urn:nbn:se:lnu:diva-123524 (URN)10.1103/PhysRevB.107.245402 (DOI)001009434900003 ()2-s2.0-85161850414 (Scopus ID)
Available from: 2023-08-09 Created: 2023-08-09 Last updated: 2024-02-01Bibliographically approved
Islam, R., Mardanya, S., Lau, A., Cuono, G., Chang, T.-R., Singh, B., . . . Autieri, C. (2023). Engineering axion insulator and other topological phases in superlattices without inversion symmetry. Physical Review B, 107(12), Article ID 125102.
Open this publication in new window or tab >>Engineering axion insulator and other topological phases in superlattices without inversion symmetry
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2023 (English)In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 107, no 12, article id 125102Article in journal (Refereed) Published
Abstract [en]

We study theoretically the interplay between magnetism and topology in three-dimensional HgTe/MnTe superlattices stacked along the (001) axis. Our results show the evolution of the magnetic topological phases with respect to the magnetic configurations. An axion insulator phase is observed for the antiferromagnetic order with the out-of-plane Néel vector direction below a critical thickness of MnTe, which is the ground state among all magnetic configurations. Defining T as the time-reversal symmetry, this axion insulator phase is protected by a magnetic twofold rotational symmetry C2⋅T. We find that the axion insulator phase evolves into a trivial insulator as we increase the number of the magnetic MnTe layers, and we present an estimate of the critical thickness of the MnTe film above which the axion insulator phase is absent. By switching the Néel vector direction into the ab plane, the system realizes different antiferromagnetic topological insulators depending on the thickness of MnTe. These phases feature gapless surface Dirac cones shifted away from high-symmetry points on surfaces perpendicular to the Néel vector direction of the magnetic layers. In the presence of ferromagnetism, the system realizes a magnetic Weyl semimetal and a ferromagnetic semimetal for out-of-plane and in-plane magnetization directions, respectively. We observe large anomalous Hall conductivity in the presence of ferromagnetism in the three-dimensional superlattice.

Place, publisher, year, edition, pages
American Physical Society, 2023
National Category
Physical Sciences
Research subject
Natural Science, Physics
Identifiers
urn:nbn:se:lnu:diva-120364 (URN)10.1103/PhysRevB.107.125102 (DOI)000945910300002 ()2-s2.0-85150894645 (Scopus ID)
Available from: 2023-04-20 Created: 2023-04-20 Last updated: 2023-06-01Bibliographically approved
Lin, C., Cai, L., Fu, J.-H., Sattar, S., Wang, Q., Wan, Y., . . . Tung, V. (2022). Direct Band Gap in Multilayer Transition Metal Dichalcogenide Nanoscrolls with Enhanced Photoluminescence. ACS Materials Letters, 4(8), 1547-1555
Open this publication in new window or tab >>Direct Band Gap in Multilayer Transition Metal Dichalcogenide Nanoscrolls with Enhanced Photoluminescence
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2022 (English)In: ACS Materials Letters, E-ISSN 2639-4979, Vol. 4, no 8, p. 1547-1555Article in journal (Refereed) Published
Abstract [en]

A direct band gap that solely exists in monolayer semiconducting transition metal dichalcogenides (TMDs) endows strong photoluminescence (PL) features, whereas multilayer TMD structures exhibit quenched PL due to the direct-to-indirect band gap transition. We demonstrate multi-layer TMD (such as MoS2 and WS2) nanoscrolls with a preserved direct band gap fabricated by an effective and facile method of solvent-driven self-assembly. The resultant multi-layer nanoscrolls, exhibiting up to 11 times higher PL intensity than the remanent monolayer, are carefully characterized using PL spectroscopy. Significantly enlarged interlayer distances and modulated interlayer coupling in the fabricated nanostructures are unveiled by cross-sectional scanning transmission electron microscopy, atomic force microscopy, and Raman spectroscopy. The preservation of direct band gap features is further evidenced by density functional theory calculations using the simplified bilayer model with an experimentally obtained 15 & ANGS; interlayer distance. The modulation of the PL intensity as an indicator of the band gap crossover in the TMD nanoscrolls is demonstrated by removing the acetone molecules trapped inside the interlayer space. The general applicability of the method presents an opportunity for large-scale fabrication of a plethora of multilayer TMD nanoscrolls with direct band gaps.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2022
National Category
Condensed Matter Physics Atom and Molecular Physics and Optics
Research subject
Physics, Condensed Matter Physics
Identifiers
urn:nbn:se:lnu:diva-116299 (URN)10.1021/acsmaterialslett.2c00162 (DOI)000835600300001 ()2-s2.0-85136209586 (Scopus ID)
Available from: 2022-09-16 Created: 2022-09-16 Last updated: 2023-01-18Bibliographically approved
Wadge, A. S., Grabecki, G., Autieri, C., Kowalski, B. J., Iwanowski, P., Cuono, G., . . . Wisniewski, A. (2022). Electronic properties of TaAs2 topological semimetal investigated by transport and ARPES. Journal of Physics: Condensed Matter, 34(12), Article ID 125601.
Open this publication in new window or tab >>Electronic properties of TaAs2 topological semimetal investigated by transport and ARPES
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2022 (English)In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 34, no 12, article id 125601Article in journal (Refereed) Published
Abstract [en]

We have performed electron transport and angle-resolved photo-emission spectroscopy ( ARPES) measurements on single crystals of transition metal dipnictide TaAs2 cleaved along the ((2) over bar 01) surface which has the lowest cleavage energy. A Fourier transform of the Shubnikov-de Haas oscillations shows four different peaks whose angular dependence was studied with respect to the angle between magnetic field and the [(2) over bar 01] direction. The results indicate elliptical shape of the Fermi surface cross- sections. Additionally, a mobility spectrum analysis was carried out, which also reveals at least four types of carriers contributing to the conductance (two kinds of electrons and two kinds of holes). ARPES spectra were taken on freshly cleaved ((2) over bar 01) surface and it was found that bulk states pockets at constant energy surface are elliptical, which confirms the magnetotransport angle dependent studies. First-principles calculations support the interpretation of the experimental results. The theoretical calculations better reproduce the ARPES data if the theoretical Fermi level (FL) is increased, which is due to a small n-doping of the samples. This shifts the FL closer to the Dirac point, allowing investigating the physics of the Dirac andWeyl points, making this compound a platform for the investigation of the Dirac andWeyl points in three-dimensional materials.

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2022
Keywords
topological semimetal, single crystal growth, electrical transport, Shubnikov de Haas oscillations, mobility spectrum analysis, angle resolved photoemission spectroscopy, DFT calculations
National Category
Condensed Matter Physics
Research subject
Physics, Condensed Matter Physics
Identifiers
urn:nbn:se:lnu:diva-109498 (URN)10.1088/1361-648X/ac43fe (DOI)000740044600001 ()34915463 (PubMedID)2-s2.0-85123393461 (Scopus ID)2022 (Local ID)2022 (Archive number)2022 (OAI)
Available from: 2022-01-19 Created: 2022-01-19 Last updated: 2023-01-18Bibliographically approved
Sattar, S., Larsson, J. A., Canali, C. M., Roche, S. & Garcia, J. H. (2022). Giant valley-polarized spin splittings in magnetized Janus Pt dichalcogenides [Letter to the editor]. Physical Review B, 105(4), Article ID L041402.
Open this publication in new window or tab >>Giant valley-polarized spin splittings in magnetized Janus Pt dichalcogenides
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2022 (English)In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 105, no 4, article id L041402Article in journal, Letter (Refereed) Published
Abstract [en]

We reveal giant proximity-induced magnetism and valley-polarization effects in Janus Pt dichalcogenides (such as SPtSe), when bound to the europium oxide (EuO) substrate. Using first-principles simulations, it is surprisingly found that the charge redistribution, resulting from proximity with EuO, leads to the formation of two K and K' valleys in the conduction bands. Each of these valleys displays its own spin polarization and a specific spin texture dictated by broken inversion and time-reversal symmetries, and valley-exchange and Rashba splittings as large as hundreds of meV. This provides a platform for exploring spin-valley physics in low-dimensional semiconductors, with potential spin transport mechanisms such as spin-orbit torques much more resilient to disorder and temperature effects.

Place, publisher, year, edition, pages
American Physical Society, 2022
National Category
Condensed Matter Physics
Research subject
Physics, Condensed Matter Physics
Identifiers
urn:nbn:se:lnu:diva-109890 (URN)10.1103/PhysRevB.105.L041402 (DOI)000742858100001 ()2-s2.0-85122643267 (Scopus ID)2022 (Local ID)2022 (Archive number)2022 (OAI)
Available from: 2022-01-27 Created: 2022-01-27 Last updated: 2023-01-18Bibliographically approved
Sattar, S., Islam, F. & Canali, C. M. (2022). Monolayer MnX and Janus XMnY (X, Y = S, Se, Te): A family of two-dimensional antiferromagnetic semiconductors. Physical Review B, 106(8), Article ID 085410.
Open this publication in new window or tab >>Monolayer MnX and Janus XMnY (X, Y = S, Se, Te): A family of two-dimensional antiferromagnetic semiconductors
2022 (English)In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 106, no 8, article id 085410Article in journal (Refereed) Published
Abstract [en]

We present first-principles results on the structural, electronic, and magnetic properties of a new family of twodimensional antiferromagnetic (AFM) manganese chalcogenides, namely, monolayer MnX and Janus XMnY (X, Y = S, Se, Te), among which monolayer MnSe was recently synthesized in experiments [Aapro et al., ACS Nano 15, 13794 (2021)]. By carrying out calculations of the phonon dispersion and ab initio molecular dynamics simulations, we first confirmed that these systems, characterized by an unconventional strongly-coupled-bilayer atomic structure [consisting of Mn atoms buckled to chalcogens forming top and bottom ferromagnetic (FM) planes with antiparallel spin orientation], are dynamically and thermally stable. The analysis of the magnetic properties shows that these materials have robust AFM order, retaining a much lower energy than the FM state even under strain. Our electronic structure calculations reveal that pristine MnX and their Janus counterparts are indirect-gap semiconductors, covering a wide energy range and displaying tunable band gaps by the application of biaxial tensile and compressive strain. Interestingly, owing to the absence of inversion and time-reversal symmetry, and the presence of an asymmetrical potential in the out-of-plane direction, Janus XMnY become spin-split gapped systems, presenting a rich physics yet to be explored. Our findings provide insights into this physics and highlight the potential for these two-dimensional manganese chalcogenides in AFM spintronics.

Place, publisher, year, edition, pages
American Physical Society, 2022
National Category
Condensed Matter Physics
Research subject
Physics, Condensed Matter Physics
Identifiers
urn:nbn:se:lnu:diva-118826 (URN)10.1103/PhysRevB.106.085410 (DOI)000909139700010 ()2-s2.0-85136158993 (Scopus ID)
Available from: 2023-01-30 Created: 2023-01-30 Last updated: 2023-03-27Bibliographically approved
Pournaghavi, N., Pertsova, A., MacDonald, A. H. & Canali, C. M. (2021). Nonlocal sidewall response and deviation from exact quantization of the topological magnetoelectric effect in axion-insulator thin films [Letter to the editor]. Physical Review B, 104(20), Article ID L201102.
Open this publication in new window or tab >>Nonlocal sidewall response and deviation from exact quantization of the topological magnetoelectric effect in axion-insulator thin films
2021 (English)In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 104, no 20, article id L201102Article in journal, Letter (Refereed) Published
Abstract [en]

Topological insulator (TI) thin films with surface magnetism are expected to exhibit a quantized anomalous Hall effect (QAHE) when the magnetizations on the top and bottom surfaces are parallel, and a quantized topological magnetoelectric effect (QTME) when the magnetizations have opposing orientations (axion-insulator phase) and the films are sufficiently thick. We present a unified picture of both effects that associates deviations from exact quantization of the QTME caused by finite thickness with nonlocality in the sidewall current response function. Using realistic tight-binding model calculations, we show that in Bi2Se3 TI thin films, deviations from quantization in the axion-insulator phase are reduced in size when the exchange coupling of tight-binding model basis states to the local magnetization near the surface is strengthened. Stronger exchange coupling also reduces the effect of potential disorder, which is unimportant for the QAHE but detrimental for the QTME, which requires that the Fermi energy lie inside the gap at all positions.

Place, publisher, year, edition, pages
American Physical Society, 2021
National Category
Condensed Matter Physics
Research subject
Physics, Condensed Matter Physics
Identifiers
urn:nbn:se:lnu:diva-108339 (URN)10.1103/PhysRevB.104.L201102 (DOI)000718024800005 ()2-s2.0-85119090228 (Scopus ID)2021 (Local ID)2021 (Archive number)2021 (OAI)
Available from: 2021-12-02 Created: 2021-12-02 Last updated: 2023-01-18Bibliographically approved
Pournaghavi, N., Islam, F., Islam, R., Autieri, C., Dietl, T. & Canali, C. M. (2021). Realization of the Chern-insulator and axion-insulator phases in antiferromagnetic MnTe/Bi2(Se, Te)3/MnTe heterostructures. Physical review B (PRB), 103(19), Article ID 1953078.
Open this publication in new window or tab >>Realization of the Chern-insulator and axion-insulator phases in antiferromagnetic MnTe/Bi2(Se, Te)3/MnTe heterostructures
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2021 (English)In: Physical review B (PRB), ISSN 2469-9950, Vol. 103, no 19, article id 1953078Article in journal (Refereed) Published
Abstract [en]

Breaking time-reversal symmetry in three-dimensional topological insulator thin films can lead to different topological quantum phases, such as the Chern insulator (CI) phase and the axion insulator (AI) phase. Using first-principles density functional theory methods, we investigate the onset of these two topological phases in a trilayer heterostructure consisting of a Bi2Se3 (Bi2Te3) TI thin film sandwiched between two antiferromagneticMnTe layers. We find that an orthogonal exchange field from the MnTe layers, stabilized by a small anisotropy barrier, opens an energy gap of the order of 10 meV at the Dirac point of the TI film. A topological analysis demonstrates that, depending on the relative orientation of the exchange field at the two interfaces, the total Chern number of the system is either C = 1 or C = 0, characteristic of the CI and AI phases, respectively. Nontopological surface states inside the energy-gap region, caused by the interface potential, complicate this identification. Remarkably though, the calculation of the anomalous Hall conductivity shows that such nontopological surface states do not affect the topology-induced transport properties. Given the size of the exchange gap, we estimate that gapless chiral edge states, leading to the quantum anomalous Hall effect, should emerge on the sidewalls of these heterostructures in the CI phase for widths > 200 nm. We also discuss the possibility of inducing transitions between the CI and the AI phases by means of the spin-orbit torque caused by the spin Hall effect in an adjacent conducting layer.

Place, publisher, year, edition, pages
American Physical Society, 2021
National Category
Condensed Matter Physics
Research subject
Physics, Condensed Matter Physics
Identifiers
urn:nbn:se:lnu:diva-103438 (URN)10.1103/PhysRevB.103.195308 (DOI)000655877500006 ()2-s2.0-85106232777 (Scopus ID)2021 (Local ID)2021 (Archive number)2021 (OAI)
Available from: 2021-05-17 Created: 2021-05-17 Last updated: 2023-01-18Bibliographically approved
Rancati, A., Pournaghavi, N., Islam, F., Debernardi, A. & Canali, C. M. (2020). Impurity-Induced Topological Phase Transitions In Cd3As2 And Na3Bi Dirac Semimetals. Physical Review B, 102(19), 195110-195123
Open this publication in new window or tab >>Impurity-Induced Topological Phase Transitions In Cd3As2 And Na3Bi Dirac Semimetals
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2020 (English)In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 102, no 19, p. 195110-195123Article in journal (Refereed) Published
Abstract [en]

Using first-principles density functional theory calculations, combined with a topological analysis, we have investigated the electronic properties of Cd3As2 and Na3Bi Dirac topological semimetals doped with nonmagnetic and magnetic impurities. Our systematic analysis shows that the selective breaking of the inversion, rotational, and time-reversal symmetry, controlled by specific choices of the impurity doping, induces phase transitions from the original Dirac semimetal to a variety of topological phases such as topological insulator, trivial semimetal, nonmagnetic and magnetic Weyl semimetal, and Chern insulator. The Dirac semimetal phase can exist only if the rotational symmetry Cn with n>2 is maintained. One particularly interesting phase emerging in doped Cd3As2 is a coexisting Dirac-Weyl phase, which occurs when only inversion symmetry is broken while time-reversal symmetry and rotational symmetry are both preserved. To further characterize the low-energy excitations of this phase, we have complemented our density functional results with a continuum four-band k⋅p model, which indeed displays nodal points of both Dirac and Weyl types. The coexisting phase appears as a transition point between two topologically distinct Dirac phases but may also survive in a small region of parameter space controlled by external strain.

Place, publisher, year, edition, pages
American Physical Society, 2020
Keywords
Topological phase transition, Weyl semimetal, Dirac semimetals
National Category
Condensed Matter Physics
Research subject
Physics, Condensed Matter Physics
Identifiers
urn:nbn:se:lnu:diva-99658 (URN)10.1103/PhysRevB.102.195110 (DOI)000587595300001 ()2-s2.0-85096340515 (Scopus ID)
Funder
Swedish Research Council, 621-2014-4785, 2017-04404
Available from: 2020-12-21 Created: 2020-12-21 Last updated: 2023-01-18Bibliographically approved
Projects
Magnetism and nanospintronics in semiconductor nanostructures, topological insulators and molecular magnets [2014-04785_VR]; Linnaeus University
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