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Canali, Carlo M.
Publications (10 of 94) Show all publications
Lei, C., Mahon, P. T., Canali, C. M. & Macdonald, A. H. (2024). Capacitive Scheme to Detect the Topological Magnetoelectric Effect. Physical Review Letters, 133(24), Article ID 246607.
Open this publication in new window or tab >>Capacitive Scheme to Detect the Topological Magnetoelectric Effect
2024 (English)In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 133, no 24, article id 246607Article in journal (Refereed) Published
Abstract [en]

The topological magnetoelectric effect (TME) is a defining property of three-dimensional Z 2 topological insulators that was predicted on theoretical grounds more than a decade ago, but has still not been directly measured. In this Letter we propose a strategy for direct measurement of the TME and discuss the precision of the effect in real devices with charge and spin disorder.

Place, publisher, year, edition, pages
American Physical Society, 2024
National Category
Condensed Matter Physics
Research subject
Physics, Condensed Matter Physics
Identifiers
urn:nbn:se:lnu:diva-134358 (URN)10.1103/PhysRevLett.133.246607 (DOI)001378803800003 ()2-s2.0-85212437116 (Scopus ID)
Available from: 2025-01-08 Created: 2025-01-08 Last updated: 2025-02-04Bibliographically approved
Pournaghavi, N. & Canali, C. M. (2024). Chiral edge transport along domain walls in magnetic topological insulator nanoribbons. Journal of Physics: Condensed Matter, 36(40), Article ID 405803.
Open this publication in new window or tab >>Chiral edge transport along domain walls in magnetic topological insulator nanoribbons
2024 (English)In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 36, no 40, article id 405803Article in journal (Refereed) Published
Abstract [en]

Quantum anomalous Hall insulators are topologically characterized by non-zero integer Chern numbers, the sign of which depends on the direction of the exchange field that breaks time-reversal symmetry. This feature allows the manipulation of the conducting chiral edge states present at the interface of two magnetic domains with opposite magnetization and opposite Chern numbers. Motivated by this broad understanding, the present study investigates the quantum transport properties of a magnetized Bi2Se3 topological insulator nanoribbon with a domain wall (DW) oriented either parallel or perpendicular to the transport direction. Employing an atomistic tight-binding model and a non-equilibrium Green's function formalism, we calculate the quantum conductance and explore the nature of the edge states. We elucidate the conditions leading to exact conductance quantization and identify the origin of deviations from this behavior. Our analysis shows that although the conductance is quantized in the presence of the horizontal DW, the quantization is absent in the perpendicular DW case. Furthermore, the investigation of the spin character of the edge modes confirms that the conductance in the horizontal DW configuration is spin polarized. This finding underscores the potential of our system as a simple three dimensional spin-filter device.

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2024
Keywords
transport, magnetic, topological phase, Chern insulator, domain wall, chiral edges
National Category
Condensed Matter Physics
Research subject
Physics, Condensed Matter Physics
Identifiers
urn:nbn:se:lnu:diva-131850 (URN)10.1088/1361-648X/ad5d34 (DOI)001268529400001 ()38941992 (PubMedID)2-s2.0-85198650786 (Scopus ID)
Available from: 2024-08-16 Created: 2024-08-16 Last updated: 2025-02-04Bibliographically approved
Lin, C., Zhao, X., Xiao, Y., Sattar, S., Tang, L., Nairan, A., . . . Leung, D. Y. .. (2024). Improving photocatalytic hydrogen generation of g-C3N4 via efficient charge separation imposed by Bi2O2Se nanosheets. Carbon, 218, Article ID 118721.
Open this publication in new window or tab >>Improving photocatalytic hydrogen generation of g-C3N4 via efficient charge separation imposed by Bi2O2Se nanosheets
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2024 (English)In: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 218, article id 118721Article in journal (Refereed) Published
Abstract [en]

Enabling highly efficient photocatalytic hydrogen production from solar-driven water splitting is of immense potential and environmental significance. However, the crucial issue of the low utilization efficiency of photogenerated charges in most photocatalysts, such as polymeric graphitic carbon nitride, g-C3N4 (CN), hampers the overall photocatalytic activity and hinders practical applications. To surmount this parasitic phenomenon, we develop a heterojunction-based strategy that improves the charge separation efficiency in CN. The heterostructure is constructed between thermally exfoliated CN and liquid phase exfoliated Bi2O2Se (BOS) via a solution-phase, electrostatically driven self-assembly process. The properly aligned band positions between the two components create a built-in electric field, which endows the composite with an enhanced charge separation efficiency. The optimized Pt-deposited heterostructure photocatalyst exhibits a hydrogen production rate of 6481 μmol h−1 g−1, and an apparent quantum efficiency of 11.65% at 420 nm, compared to those of Pt-deposited ECN (4595 μmol h−1 g−1, 6.64 %). We validate the efficient charge separation effect and the prolonged lifetime of photogenerated carriers in the heterostructure using a series of comprehensive characterizations across multiple timescales, thus, elucidating the origin of the observed photocatalytic activity. This demonstration offers valuable insights into improving the utilization efficiency of photogenerated charges for photocatalysis by heterostructure engineering with materials of distinct electronic configurations.

Place, publisher, year, edition, pages
Elsevier, 2024
National Category
Physical Chemistry Condensed Matter Physics
Research subject
Physics, Condensed Matter Physics
Identifiers
urn:nbn:se:lnu:diva-128658 (URN)10.1016/j.carbon.2023.118721 (DOI)001143682100001 ()2-s2.0-85180531492 (Scopus ID)
Available from: 2024-04-08 Created: 2024-04-08 Last updated: 2025-02-04Bibliographically approved
Islam, M. F., Withanage, K. P. K., Canali, C. M. & Pederson, M. R. (2024). Noncollinear first-principles studies of the spin-electric coupling in frustrated triangular molecular magnets. Physical Review B, 109(21), Article ID 214407.
Open this publication in new window or tab >>Noncollinear first-principles studies of the spin-electric coupling in frustrated triangular molecular magnets
2024 (English)In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 109, no 21, article id 214407Article in journal (Refereed) Published
Abstract [en]

Frustrated triangular molecular magnets (MMs) with antiferromagnetic ground states (GSs) are an important class of magnetic systems with potential applications in quantum information processing. The twofold degenerate GS of these molecules, characterized by spin chirality, can be utilized to encode qubits for quantum computing. Furthermore, because of the lack of inversion symmetry in these molecules, an electric field couples directly states of opposite chirality, allowing a very efficient and fast control of the qubits. In this paper we present a theoretical method to calculate the spin-electric coupling for triangular MMs with effective local spins s larger than 1/2, which is amenable to a first-principles implementation based on density functional theory (DFT). In contrast to MMs where the net magnetization at the magnetic atoms is mu(B)/2 (mu(B) is the Bohr magneton), the DFT treatment of frustrated triangular MMs with larger local magnetizations requires a fully noncollinear approach, which we have implemented in the NRLMOL DFT code. As an example, we have used these methods to evaluate the spin-electric coupling for a spin s = 5/2 {Fe-3} triangular MM, where this effect has been observed experimentally for the first time quite recently. Our theoretical and computational methods will help elucidate and further guide ongoing experimental work in the field of quantum molecular spintronics.

Place, publisher, year, edition, pages
American Physical Society, 2024
National Category
Condensed Matter Physics
Research subject
Physics, Condensed Matter Physics
Identifiers
urn:nbn:se:lnu:diva-134820 (URN)10.1103/PhysRevB.109.214407 (DOI)001393416800005 ()2-s2.0-85195188018 (Scopus ID)
Available from: 2025-01-23 Created: 2025-01-23 Last updated: 2025-02-04Bibliographically approved
Hussain, G., Cuono, G., Dziawa, P., Janaszko, D., Sadowski, J., Kret, S., . . . Autieri, C. (2024). Pentagonal nanowires from topological crystalline insulators: a platform for intrinsic core-shell nanowires and higher-order topology. Nanoscale Horizons, 9, 1290-1300
Open this publication in new window or tab >>Pentagonal nanowires from topological crystalline insulators: a platform for intrinsic core-shell nanowires and higher-order topology
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2024 (English)In: Nanoscale Horizons, ISSN 2055-6764, E-ISSN 2055-6756, Vol. 9, p. 1290-1300Article in journal (Refereed) Published
Abstract [en]

We report on the experimental realization of Pb1-xSnx Te pentagonal nanowires (NWs) with [110] orientation using molecular beam epitaxy techniques. Using first-principles calculations, we investigate the structural stability of NWs of SnTe and PbTe in three different structural phases: cubic, pentagonal with [001] orientation and pentagonal with [110] orientation. Within a semiclassical approach, we show that the interplay between ionic and covalent bonds favors the formation of pentagonal NWs. Additionally, we find that this pentagonal structure is more likely to occur in tellurides than in selenides. The disclination and twin boundary cause the electronic states originating from the NW core region to generate a conducting band connecting the valence and conduction bands, creating a symmetry-enforced metallic phase. The metallic core band has opposite slopes in the cases of Sn and Te twin boundaries, while the bands from the shell are insulating. We finally study the electronic and topological properties of pentagonal NWs unveiling their potential as a new platform for higher-order topology and fractional charge. These pentagonal NWs represent a unique case of intrinsic core-shell one-dimensional nanostructures with distinct structural, electronic and topological properties between the core and the shell region. (a) Scanning transmission electron microscopy image of a pentagonal nanowire; the inset shows the disclination and core chain (CC). The red bands from the core connect the valence and conduction bands for (b) cation and (c) anion twin-boundaries.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2024
National Category
Condensed Matter Physics
Research subject
Physics, Condensed Matter Physics
Identifiers
urn:nbn:se:lnu:diva-130448 (URN)10.1039/d4nh00019f (DOI)001232868100001 ()38804204 (PubMedID)2-s2.0-85194373095 (Scopus ID)
Available from: 2024-06-14 Created: 2024-06-14 Last updated: 2025-02-04Bibliographically approved
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: 2025-02-04Bibliographically 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: 2025-02-04Bibliographically 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: 2025-02-04Bibliographically 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
Projects
Magnetism and nanospintronics in semiconductor nanostructures, topological insulators and molecular magnets [2014-04785_VR]; Linnaeus University
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