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Choudhury A, Maitra T. First principles prediction of novel quantum topological insulator state in two-dimensional XMg 2Bi 2(X=Eu/Yb). JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2024; 36:375501. [PMID: 38815601 DOI: 10.1088/1361-648x/ad5261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2024] [Accepted: 05/30/2024] [Indexed: 06/01/2024]
Abstract
Topological insulator (TIs), a novel quantum state of materials, has a lot of significance in the development of low-power electronic equipments as the conducting edge states display exceptional endurance against back-scattering. The absence of suitable materials with high fabrication feasibility and significant nontrivial bandgap, is now the biggest hurdle in their potential applications in devices. Here, we illustrate using first principles density functional calculations that the quintuplet layers of EuMg2Bi2and YbMg2Bi2crystals are potential two-dimensional TIs with a sizeable nontrivial gaps of 72 meV and 147 meV respectively. Dynamical stability of these quintuplet layers of EuMg2Bi2and YbMg2Bi2is confirmed by our phonon calculations. The weakly coupled layered structure of parent compounds makes it possible for simple exfoliation from a three-dimensional structure. We observed gapless edge states inside the bulk band gap in both the systems which indicate their TI nature. Further, we observed the anomalous and spin Hall conductivities to be quantized in two dimensional EuMg2Bi2and YbMg2Bi2respectively. Our findings predict two viable candidate materials as two dimensional quantum TIs which can be explored by future experimental investigations and possible applications of quantized spin and anomalous Hall conductance in spintronics.
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Affiliation(s)
- Amarjyoti Choudhury
- Department of Physics, Indian Institute of Technology Roorkee, Roorkee 247667, Uttarakhand, India
| | - T Maitra
- Department of Physics, Indian Institute of Technology Roorkee, Roorkee 247667, Uttarakhand, India
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Mukherjee S, Rana N, Goswami S, Das S, Singha P, Chatterjee S, Bandyopadhyay S, Banerjee A. Tuning of thermoelectric performance by modulating vibrational properties in Ni-doped Sb 2Te 3. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2024; 36:365701. [PMID: 38776956 DOI: 10.1088/1361-648x/ad4f3b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Accepted: 05/22/2024] [Indexed: 05/25/2024]
Abstract
Sb2Te3, a binary chalcogenide-based 3D topological insulator, attracts significant attention for its exceptional thermoelectric performance. We report the vibrational properties of magnetically doped Sb2Te3thermoelectric material. Ni doping induces defect/disorder in the system and plays a positive role in engineering the thermoelectric properties through tuning the vibrational phonon modes. Synchrotron powder x-ray diffraction study confirms good crystalline quality and single-phase nature of the synthesized samples. The change in structural parameters, includingBisoand strain, further corroborate with structural disorder. Detailed modification of phonon modes with doping and temperature variation is analysed from temperature-dependent Raman spectroscopic measurement. Compressive lattice strain is observed from the blue shift of Raman peaks owing to Ni incorporation in Sb site. An attempt is made to extract the lattice thermal conductivity from total thermal conductivity estimated through optothermal Raman studies. Hall concentration data support the change in temperature-dependent resistivity and thermopower. Remarkable increase in thermopower is observed after Ni doping. Simulation of the Pisarenko model, indicating the convergence of the valence band, explains the observed enhancement of thermopower in Sb2-xNixTe3. The energy gap between the light and heavy valence band at Γ point is found to be 30 meV (for Sb2Te3), which is reduced to 3 meV (in Sb1.98Ni0.02Te3). A significant increase in thermoelectric power factor is obtained from 715 μWm-1K-2for pristine Sb2Te3to 2415 μWm-1K-2for Ni-doped Sb2Te3sample. Finally, the thermoelectric figure of merit,ZTis found to increase by four times in Sb1.98Ni0.02Te3than that of its pristine counterpart.
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Affiliation(s)
- Suchandra Mukherjee
- Department of Physics, University of Calcutta, 92 A P C Road, Kolkata, West Bengal 700 009, India
| | - Nabakumar Rana
- Department of Physics, University of Calcutta, 92 A P C Road, Kolkata, West Bengal 700 009, India
| | - Swapnadeep Goswami
- Department of Physics, University of Calcutta, 92 A P C Road, Kolkata, West Bengal 700 009, India
| | - Subarna Das
- New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur PO, Bangalore 560064, India
| | - Pintu Singha
- School of Physics, Indian Institute of Science Education and Research, Maruthamala PO, Thiruvananthapuram, Kerala 695 551, India
| | - Souvik Chatterjee
- UGC-DAE Consortium for Scientific Research, Kolkata Centre, , Sector III, LB-8, Salt Lake, Kolkata 700 106, India
| | - Sudipta Bandyopadhyay
- Department of Physics, University of Calcutta, 92 A P C Road, Kolkata, West Bengal 700 009, India
- Center for Research in Nanoscience and Nanotechnology, University of Calcutta, JD-2, Sector-III, Saltlake, Kolkata 700 106, India
| | - Aritra Banerjee
- Department of Physics, University of Calcutta, 92 A P C Road, Kolkata, West Bengal 700 009, India
- Center for Research in Nanoscience and Nanotechnology, University of Calcutta, JD-2, Sector-III, Saltlake, Kolkata 700 106, India
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3
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Bai Y, Zhang L, Mao N, Li R, Chen Z, Dai Y, Huang B, Niu C. Coupled Electronic and Magnonic Topological States in Two-Dimensional Ferromagnets. ACS NANO 2024; 18:13377-13383. [PMID: 38728267 DOI: 10.1021/acsnano.4c03529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2024]
Abstract
Magnetic materials offer a fertile playground for fundamental physics discovery, with not only electronic but also magnonic topological states intensively explored. However, one natural material with both electronic and magnonic nontrivial topologies is still unknown. Here, we demonstrate the coexistence of first-order topological magnon insulators (TMIs) and electronic second-order topological insulators (SOTIs) in 2D honeycomb ferromagnets, giving rise to the nontrivial corner states being connected by the charge-free magnonic edge states. We show that, with C 3 symmetry, the phase factor ± ϕ caused by the next nearest-neighbor Dzyaloshinskii-Moriya interaction breaks the pseudo-spin time-reversal symmetry T , which leads to the split of magnon bands, i.e., the emergence of TMIs with a nonzero Chern number of C = - 1 , in experimentally feasible candidates of MoI3, CrSiTe3, and CrGeTe3 monolayers. Moreover, protected by the C 3 symmetry, the electronic SOTIs characterized by nontrivial corner states are obtained, bridging the topological aspect of fermions and bosons with a high possibility of innovative applications in spintronics devices.
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Affiliation(s)
- Yingxi Bai
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, China
| | - Lichuan Zhang
- School of Physics and Electronic Engineering, Jiangsu University, Zhenjiang 212013, China
| | - Ning Mao
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, China
| | - Runhan Li
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, China
| | - Zhiqi Chen
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, China
| | - Ying Dai
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, China
| | - Baibiao Huang
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, China
| | - Chengwang Niu
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, China
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Zou X, Li R, Chen Z, Dai Y, Huang B, Niu C. Engineering Gapless Edge States from Antiferromagnetic Chern Homobilayer. NANO LETTERS 2024; 24:450-457. [PMID: 38112315 DOI: 10.1021/acs.nanolett.3c04304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2023]
Abstract
We put forward that stacked Chern insulators with opposite chiralities offer a strategy to achieve gapless helical edge states in two dimensions. We employ the square lattice as an example and elucidate that the gapless chiral and helical edge states emerge in the monolayer and antiferromagnetically stacked bilayer, characterized by Chern number C = - 1 and spin Chern number C S = - 1 , respectively. Particularly, for a topological phase transition to the normal insulator in the stacked bilayer, a band gap closing and reopening procedure takes place accompanied by helical edge states disappearing, where the Chern insulating phase in the monolayer vanishes at the same time. Moreover, EuO is revealed as a suitable candidate for material realization. This work is not only valuable to the research of the quantum anomalous Hall effect but also offers a favorable platform to realize magnetic topologically insulating materials for spintronics applications.
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Affiliation(s)
- Xiaorong Zou
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan, Shandong 250100, China
| | - Runhan Li
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan, Shandong 250100, China
| | - Zhiqi Chen
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan, Shandong 250100, China
| | - Ying Dai
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan, Shandong 250100, China
| | - Baibiao Huang
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan, Shandong 250100, China
| | - Chengwang Niu
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan, Shandong 250100, China
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Zhang X, Wang X, He T, Wang L, Yu WW, Liu Y, Liu G, Cheng Z. Magnetic topological materials in two-dimensional: theory, material realization and application prospects. Sci Bull (Beijing) 2023; 68:2639-2657. [PMID: 37734982 DOI: 10.1016/j.scib.2023.09.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 07/12/2023] [Accepted: 08/23/2023] [Indexed: 09/23/2023]
Abstract
Two-dimensional (2D) magnetism and nontrivial band topology are both areas of research that are currently receiving significant attention in the study of 2D materials. Recently, a novel class of materials has emerged, known as 2D magnetic topological materials, which elegantly combine 2D magnetism and nontrivial topology. This field has garnered increasing interest, especially due to the emergence of several novel magnetic topological states that have been generalized into the 2D scale. These states include antiferromagnetic topological insulators/semimetals, second-order topological insulators, and topological half-metals. Despite the rapid advancements in this emerging research field in recent years, there have been few comprehensive summaries of the state-of-the-art progress. Therefore, this review aims to provide a thorough analysis of current progress on 2D magnetic topological materials. We cover various 2D magnetic topological insulators, a range of 2D magnetic topological semimetals, and the novel 2D topological half-metals, systematically analyzing the basic topological theory, the course of development, the material realization, and potential applications. Finally, we discuss the challenges and prospects for 2D magnetic topological materials, highlighting the potential for future breakthroughs in this exciting field.
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Affiliation(s)
- Xiaoming Zhang
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, and School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130, China
| | - Xiaotian Wang
- School of Physical Science and Technology, Southwest University, Chongqing 400715, China
| | - Tingli He
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, and School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130, China
| | - Lirong Wang
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, and School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130, China
| | - Wei-Wang Yu
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, and School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130, China
| | - Ying Liu
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, and School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130, China
| | - Guodong Liu
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, and School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130, China.
| | - Zhenxiang Cheng
- Institute for Superconducting and Electronic Materials (ISEM), University of Wollongong, Wollongong 2500, Australia.
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Prediction of topological Dirac semimetal in Ca-based Zintl layered compounds CaM 2X 2 (M = Zn or Cd; X = N, P, As, Sb, or Bi). Sci Rep 2022; 12:4582. [PMID: 35301355 PMCID: PMC8930984 DOI: 10.1038/s41598-022-08370-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 03/08/2022] [Indexed: 11/10/2022] Open
Abstract
Topological Dirac materials are attracting a lot of attention because they offer exotic physical phenomena. An exhaustive search coupled with first-principles calculations was implemented to investigate 10 Zintl compounds with a chemical formula of CaM2X2 (M = Zn or Cd, X = N, P, As, Sb, or Bi) under three crystal structures: CaAl2Si2-, ThCr2Si2-, and BaCu2S2-type crystal phases. All of the materials were found to energetically prefer the CaAl2Si2-type structure based on total ground state energy calculations. Symmetry-based indicators are used to evaluate their topological properties. Interestingly, we found that CaM2Bi2 (M = Zn or Cd) are topological crystalline insulators. Further calculations under the hybrid functional approach and analysis using k · p model reveal that they exhibit topological Dirac semimetal (TDSM) states, where the four-fold degenerate Dirac points are located along the high symmetry line in-between Г to A points. These findings are verified through Green's function surface state calculations under HSE06. Finally, phonon spectra calculations revealed that CaCd2Bi2 is thermodynamically stable. The Zintl phase of AM2X2 compounds have not been identified in any topological material databases, thus can be a new playground in the search for new topological materials.
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Guo SD, Mu WQ, Xiao XB, Liu BG. Generalization of piezoelectric quantum anomalous Hall insulator based on monolayer Fe 2I 2: a first-principles study. Phys Chem Chem Phys 2021; 23:25994-26003. [PMID: 34783808 DOI: 10.1039/d1cp04123a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
To easily synthesize a piezoelectric quantum anomalous Hall insulator (PQAHI), the Janus monolayer Fe2IBr (FeI0.5Br0.5) as a representative PQAHI, is generalized to monolayer FeI1-xBrx (x = 0.25 and 0.75) with α and β phases. By first-principles calculations, it is proved that monolayer FeI1-xBrx (x = 0.25 and 0.75) are dynamically, mechanically and thermally stable. They are excellent room-temperature PQAHIs with high Curie temperatures, sizable gaps and high Chern number (C = 2). Because the considered crystal structures of α and β phases possess Mx and My mirror symmetries, the topological properties of monolayer FeI1-xBrx (x = 0.25 and 0.75) are maintained. Namely, if the constructed structures have Mx and My mirror symmetries, the mixing ratio of Br and I atoms can be generalized for other proportions. It is also found that different crystal phases have important effects on the out-of-plane piezoelectric response, and the piezoelectric strain coefficient, d32, of the β phase is higher than or comparable with those of other known two-dimensional (2D) materials. To further confirm this idea, the physical and chemical properties of monolayer LiFeSe0.75S0.25 with α and β phases, as a generalization of PQAHI LiFeSe0.5S0.5, is investigated, as it has a similar electronic structure, magnetic and topological properties as LiFeSe0.5S0.5. Our work provides a practical guide to achieve PQAHIs experimentally, and the combination of piezoelectricity, topological and ferromagnetic (FM) orders makes Fe2I2-based monolayers a potential platform for multi-functional spintronics and piezoelectric electronics.
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Affiliation(s)
- San-Dong Guo
- School of Electronic Engineering, Xi'an University of Posts and Telecommunications, Xi'an 710121, People's Republic of China.
| | - Wen-Qi Mu
- School of Electronic Engineering, Xi'an University of Posts and Telecommunications, Xi'an 710121, People's Republic of China.
| | - Xiang-Bo Xiao
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China.,School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Bang-Gui Liu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China.,School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, People's Republic of China
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Parfenov OE, Averyanov DV, Sokolov IS, Taldenkov AN, Karateev IA, Tokmachev AM, Storchak VG. High Carrier Mobility in a Layered Antiferromagnet Integrated with Silicon. ACS APPLIED MATERIALS & INTERFACES 2021; 13:41926-41932. [PMID: 34436853 DOI: 10.1021/acsami.1c13623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Coupling various functional properties in one material is always a challenge, more so if the material should be nanostructured for practical applications. Magnetism and high carrier mobility are key components for spintronic applications but rather difficult to bundle together. Here, we establish EuAl2Si2 as a layered antiferromagnet supporting high carrier mobility. Its topotactic synthesis via a sacrificial two-dimensional template results in epitaxial nanoscale films on silicon. Their outstanding structural quality and atomically sharp interfaces are demonstrated by diffraction and microscopy techniques. EuAl2Si2 films exhibit extreme magnetoresistance and a carrier mobility of above 10,000 cm2 V-1 s-1. The marriage of these properties and magnetism makes EuAl2Si2 a promising spintronic material. Importantly, the seamless integration of EuAl2Si2 with silicon technology is particularly appealing for applications.
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Affiliation(s)
- Oleg E Parfenov
- National Research Center "Kurchatov Institute", Kurchatov Sq. 1, 123182 Moscow, Russia
| | - Dmitry V Averyanov
- National Research Center "Kurchatov Institute", Kurchatov Sq. 1, 123182 Moscow, Russia
| | - Ivan S Sokolov
- National Research Center "Kurchatov Institute", Kurchatov Sq. 1, 123182 Moscow, Russia
| | - Alexander N Taldenkov
- National Research Center "Kurchatov Institute", Kurchatov Sq. 1, 123182 Moscow, Russia
| | - Igor A Karateev
- National Research Center "Kurchatov Institute", Kurchatov Sq. 1, 123182 Moscow, Russia
| | - Andrey M Tokmachev
- National Research Center "Kurchatov Institute", Kurchatov Sq. 1, 123182 Moscow, Russia
| | - Vyacheslav G Storchak
- National Research Center "Kurchatov Institute", Kurchatov Sq. 1, 123182 Moscow, Russia
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Ogunbunmi MO, Baranets S, Childs AB, Bobev S. The Zintl phases AIn 2As 2 (A = Ca, Sr, Ba): new topological insulators and thermoelectric material candidates. Dalton Trans 2021; 50:9173-9184. [PMID: 34121098 DOI: 10.1039/d1dt01521d] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Recently, there has been a lot of interest in topological insulators (TIs), being electronic materials, which are insulating in their bulk but with the gapless exotic metallic state on their surface. The surface states observed in such materials behave as a perfect conductor thereby making them more suited for several cutting-edge technological applications such as spintronic devices. Here, we report the synthesis and structural characterization of the Zintl phases AIn2As2 (A = Ca, Sr, Ba), which could become a new class of TIs. Crystal structure elucidation by single-crystal X-ray diffraction reveals that CaIn2As2 and SrIn2As2 are isostructural and crystallize in the EuIn2P2 structure type (space group P63/mmc, no. 194, Z = 2) with unit cell parameters a = 4.1482(6) Å, c = 17.726(4) Å; and a = 4.2222(6) Å, c = 18.110(3) Å, respectively. Their hexagonal structure is made up of alternating [In2As2]2- layers separated by slabs of A2+ cations. BaIn2As2 on the other hand crystallizes in the monoclinic EuGa2P2 structure type (space group P2/m, no. 10, Z = 4) with unit cell parameters a = 10.2746(11) Å, b = 4.3005(5) Å, c = 13.3317(14) Å and β = 95.569(2)°. This structure is also layered, and it is made up of different type of polyanionic [In2As2]2- units and Ba2+ cations. The valence electron count for all three compounds adheres to the Zintl-Klemm formalism, and all elements achieve closed-shell electronic configurations. Bulk electronic structure calculations indicate the opening of a bandgap Eg ∼ 0.03 eV (CaIn2As2 and Sr2In2As2), and Eg ∼0.21 eV (BaIn2As2) in the absence of strain and spin-orbit coupling (SOC). These results argue in favor of the realization of a nontrivial topological insulator state under the influence of tensile strain and SOC. Preliminary transport properties on BaIn2As2 are suggestive of a degenerate p-type semiconductor-a behavior which is sought after in thermoelectric (TE) materials. Since both TIs and excellent TE materials are known to favor the same material properties such as narrow bandgap, heavy elements, and strong SOC, these three Zintl phases are also projected as candidates TE materials.
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Affiliation(s)
- Michael O Ogunbunmi
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, USA.
| | - Sviatoslav Baranets
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, USA.
| | - Amanda B Childs
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, USA.
| | - Svilen Bobev
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, USA.
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