Quantum anomalous Hall effect in monolayers Ti2X2 (X = P, As, Sb, Bi) with tunable Chern numbers by adjusting magnetization orientation
Keer Huang1, Lei Li1,2,3(), Wu Zhao4, Xuewen Wang1,2,3
. Frontiers Science Center for Flexible Electronics (FSCFE) & Institute of Flexible Electronics (IFE), Northwestern Polytechnical University, Xi’an 710072, China . MIIT Key Laboratory of Flexible Electronics (KLoFE), Northwestern Polytechnical University, Xi’an 710072, China . Shaanxi Key Laboratory of Flexible Electronics (KLoFE), Northwestern Polytechnical University, Xi’an 710072, China . School of Information Science and Technology, Northwest University, Xi’an 710072, China
Despite extensive research, the achievement of tunable Chern numbers in quantum anomalous Hall (QAH) systems remains a challenge in the field of condensed matter physics. Here, we theoretically proposed that Ti2X2 (X = P, As, Sb, Bi) can realize tunable Chern numbers QAH effect by adjusting their magnetization orientations. In the case of Ti2P2 and Ti2As2, if the magnetization lies in the x−y plane, and all C2 symmetries are broken, a low-Chern-number phase with C = 1 will manifest. Conversely, if the magnetization is aligned to the z-axis, the systems enter a high-Chern number phase with C = 3. As for Ti2Sb2 and Ti2Bi2, by manipulating the in-plane magnetization orientation, these systems can periodically enter topological phases (C = ±1) over a 60° interval. Adjusting the magnetization orientation from +z to −z will result in the systems’ Chern number alternating between ±1. The non-trivial gap in monolayer Ti2X2 (X = P, As, Sb, Bi) can reach values of 23.4, 54.4, 60.8, and 88.2 meV, respectively. All of these values are close to the room-temperature energy scale. Furthermore, our research has revealed that the application of biaxial strain can effectively modify the magnetocrystalline anisotropic energy, which is advantageous in the manipulation of magnetization orientation. This work provides a family of large-gap QAH insulators with tunable Chern numbers, demonstrating promising prospects for future electronic applications.
Fig.1 (a) Top, side, and oblique views of the Ti2X2 monolayers. (b) First Brillouin zone with marked high symmetry points. and are reciprocal lattice vectors. (c) Schematic diagram of the d-orbital distribution of Ti atoms in the Ti2X2 (X = P, As, Sb, Bi) monolayers.
a (Å)
d (Å)
()
D (meV)
(meV)
(meV)
Ti2P2
4.117
3.056
114.014
0.292
55.734
−1.762
Ti2As2
4.198
3.070
111.426
0.744
80.901
5.495
Ti2Sb2
4.383
3.094
105.374
−0.122
99.214
10.830
Ti2Bi2
4.425
3.090
102.676
−4.490
100.679
17.704
Tab.1 Calculated optimized lattice constants (a), nearest Ti-Ti distances (d), Ti−X−Ti angles [; see Fig.1(a)], magnetocrystalline anisotropic energy (D), magnetic coupling parameters of and for the Ti2X2 (X = P, As, Sb, Bi) monolayers.
Fig.2 (a−d) Band structures of the Ti2P2, Ti2As2, Ti2Sb2, and Ti2Bi2 monolayers without SOC, respectively. The red and blue colors indicate the spin-up and spin-down bands, respectively. (e−h)d-orbital resolved band structures of the Ti2P2, Ti2As2, Ti2Sb2, and Ti2Bi2 monolayers without SOC, respectively.
Fig.3 (a) Bulk band structure of monolayer Ti2As2 along high symmetry line K− and corresponding anomalous Hall conductivity considering SOC and magnetization lying in x−y plane for . (b) Corresponding energy spectra of semi-infinite ribbon of monolayer Ti2As2 for . Note that there is one gapless edge mode in the gap. (e, f) are similar to those in (a, b) but with magnetization along z-axis. Note that there are three gapless edge modes in the gap. (d) The distribution of the Berry curvatures for monolayer Ti2As2 with in-plane magnetization along direction and (h) out-of-plane magnetization along z-axis, respectively. (c) Phase diagram of Chern number as a function of azimuthal angle () for in-plane magnetization. (g) Phase diagram of Chern number as a function of polar angle () for the out-of-plane magnetization along path. The polar radius indicates the value of band gap (in meV).
Fig.4 (a) Bulk band structure of monolayer Ti2Sb2 along high symmetry line M−K− considering SOC and magnetization lying in x−y plane for . (b) Corresponding energy spectra of semi-infinite ribbon of monolayer Ti2Sb2 for . (c) Phase diagram of Chern number as a function of azimuthal angle () for in-plane magnetization. (d, e) are similar to those in (a, b) but with magnetization along the z direction. (f) Phase diagram of Chern number as a function of polar angle () for the out-of-plane magnetization along path.
Fig.5 Magnetocrystalline anisotropic energy of monolayers (a) Ti2P2, (b) Ti2As2, (c) Ti2Sb2, and (d) Ti2Bi2 as a function of applied biaxial strain, respectively.
Li P., Yang X., S. Jiang Q., Z. Wu Y., and Xun W., Built-in electric field and strain tunable valley-related multiple topological phase transitions in VSiXN4 (X = C, Si, Ge, Sn, Pb) monolayers, Phys. Rev. Mater. 7(6), 064002 (2023) https://doi.org/10.1103/PhysRevMaterials.7.064002
3
Huan H., Xue Y., Zhao B., Y. Gao G., R. Bao H., and Q. Yang Z., Strain-induced half-valley metals and topological phase transitions in MBr2 monolayers (M = Ru, Os), Phys. Rev. B 104(16), 165427 (2021) https://doi.org/10.1103/PhysRevB.104.165427
4
Li P., Prediction of intrinsic two dimensional ferromagnetism realized quantum anomalous Hall effect, Phys. Chem. Chem. Phys. 21(12), 6712 (2019) https://doi.org/10.1039/C8CP07781A
5
I. Halperin B., Quantized Hall conductance, current-carrying edge states, and the existence of extended states in a two-dimensional disordered potential, Phys. Rev. B 25(4), 2185 (1982) https://doi.org/10.1103/PhysRevB.25.2185
Chi H. and S. Moodera J., Progress and prospects in the quantum anomalous Hall effect, APL Mater. 10(9), 090903 (2022) https://doi.org/10.1063/5.0100989
Cai J., Anderson E., Wang C., Zhang X., Liu X., Holtzmann W., Zhang Y., Fan F., Taniguchi T., Watanabe K., Ran Y., Cao T., Fu L., Xiao D., Yao W., and Xu X., Signatures of fractional quantum anomalous Hall states in twisted MoTe2, Nature 622(7981), 63 (2023) https://doi.org/10.1038/s41586-023-06289-w
12
Deng P., Zhang P., Eckberg C., K. Chong S., Yin G., Emmanouilidou E., Che X., Ni N., and L. Wang K., Quantized resistance revealed at the criticality of the quantum anomalous Hall phase transitions, Nat. Commun. 14(1), 5558 (2023) https://doi.org/10.1038/s41467-023-40784-y
13
M. Ferguson G., Xiao R., R. Richardella A., Low D., Samarth N., and C. Nowack K., Direct visualization of electronic transport in a quantum anomalous Hall insulator, Nat. Mater. 22, 1100 (2023) https://doi.org/10.1038/s41563-023-01622-0
14
J. Guo P., X. Liu Z., and Y. Lu Z., Quantum anomalous Hall effect in collinear antiferromagnetism, npj Comput. Mater. 9(1), 70 (2023) https://doi.org/10.1038/s41524-023-01025-4
15
L. Jiao Y., T. Zeng X., Chen C., Gao Z., Y. Song K., L. Sheng X., and A. Yang S., Monolayer and bilayer PtCl3: Energetics, magnetism, and band topology, Phys. Rev. B 107(7), 075436 (2023) https://doi.org/10.1103/PhysRevB.107.075436
16
Li J. and Q. Wu R., Electrically tunable topological phase transition in van der Waals heterostructures, Nano Lett. 23(6), 2173 (2023) https://doi.org/10.1021/acs.nanolett.2c04708
17
S. Li S., Y. Li X., X. Ji W., Li P., S. Yan S., and W. Zhang C., Quantum anomalous Hall effect with a high and tunable Chern number in monolayer NdN2, Phys. Chem. Chem. Phys. 25(27), 18275 (2023) https://doi.org/10.1039/D3CP01010D
18
Y. Li X., F. Xu X., Zhou H., X. Jia H., Wang E., X. Fu H., T. Sun J., and Meng S., Tunable topological states in stacked Chern insulator bilayers, Nano Lett. 23(7), 2839 (2023) https://doi.org/10.1021/acs.nanolett.3c00154
19
Park H., Cai J., Anderson E., Zhang Y., Zhu J., Liu X., Wang C., Holtz-mann W., Hu C., Liu Z., Taniguchi T., Watanabe K., H. Chu J., Cao T., Fu L., Yao W., Z. Chang C., Cobden D., Xiao D., and Xu X., Observation of fractionally quantized anomalous Hall effect, Nature 622(7981), 74 (2023) https://doi.org/10.1038/s41586-023-06536-0
20
Zhang P., P. Balakrishnan P., Eckberg C., Deng P., Nozaki T., K. Chong S., Quarterman P., E. Holtz M., B. Maranville B., Qiu G., Pan L., Emmanouilidou E., Ni N., Sahashi M., Grutter A., and L. Wang K., Exchange biased quantum anomalous Hall effect, Adv. Mater. 35(31), 2300391 (2023) https://doi.org/10.1002/adma.202300391
21
Zhang S., M. Zhang X., Q. He Z., Jin L., Liu C., Liu Y., and D. Liu G., Weyl nodal lines, Weyl points and the tunable quantum anomalous Hall effect in two-dimensional multiferroic metal oxynitride: Tl2NO2, Nanoscale 15(34), 14018 (2023) https://doi.org/10.1039/D3NR01606D
22
F. Zhao Y., Zhang R., Cai J., Zhuo D., J. Zhou L., J. Yan Z., H. W. Chan M., Xu X., and Z. Chang C., Creation of chiral interface channels for quantized transport in magnetic topological insulator multilayer heterostructures, Nat. Commun. 14(1), 770 (2023) https://doi.org/10.1038/s41467-023-36488-y
23
J. Zhou L., B. Mei R., F. Zhao Y., X. Zhang R., Y. Zhuo D., J. Yan Z., Yuan W., Kayyalha M., H. W. Chan M., X. Liu C., and Z. Chang C., Confinement-induced chiral edge channel interaction in quantum anomalous Hall insulators, Phys. Rev. Lett. 130(8), 086201 (2023) https://doi.org/10.1103/PhysRevLett.130.086201
24
Gao Y., Y. Zhang Y., T. Sun J., Zhang L., Zhang S., and Du S., Quantum anomalous Hall effect in two-dimensional Cu-dicyanobenzene coloring-triangle lattice, Nano Res. 13(6), 1571 (2020) https://doi.org/10.1007/s12274-020-2772-2
25
Z. Chang C., Zhang J., Feng X., Shen J., Zhang Z., Guo M., Li K., Ou Y., Wei P., L. Wang L., Q. Ji Z., Feng Y., Ji S., Chen X., Jia J., Dai X., Fang Z., C. Zhang S., He K., Wang Y., Lu L., C. Ma X., and K. Xue Q., Experimental observation of the quantum anomalous Hall effect in a magnetic topological insulator, Science 340(6129), 167 (2013) https://doi.org/10.1126/science.1234414
26
Deng Y., Yu Y., Z. Shi M., Guo Z., Xu Z., Wang J., H. Chen X., and Zhang Y., Quantum anomalous Hall effect in intrinsic magnetic topological insulator MnBi2Te4, Science 367(6480), 895 (2020) https://doi.org/10.1126/science.aax8156
27
Wang J., Lian B., Zhang H., Xu Y., and C. Zhang S., Quantum anomalous Hall effect with higher plateaus, Phys. Rev. Lett. 111(13), 136801 (2013) https://doi.org/10.1103/PhysRevLett.111.136801
28
Z. Chang C., Zhao W., Y. Kim D., Wei P., K. Jain J., Liu C., H. W. Chan M., and S. Moodera J., Zero-field dissipationless chiral edge transport and the nature of dissipation in the quantum anomalous Hall state, Phys. Rev. Lett. 115(5), 057206 (2015) https://doi.org/10.1103/PhysRevLett.115.057206
29
X. Wang Y. and Li F., High Chern number phase in topological insulator multilayer structures, Phys. Rev. B 104(3), 035202 (2021) https://doi.org/10.1103/PhysRevB.104.035202
30
Bosnar M., Y. Vyazovskaya A., K. Petrov E., V. Chulkov E., and M. Otrokov M., High Chern number van der Waals magnetic topological multilayers MnBi2Te4/hBN, npj 2D Mater. Appl. 7(1), 33 (2023) https://doi.org/10.1038/s41699-023-00396-y
31
Ge J., Liu Y., Li J., Li H., Luo T., Wu Y., Xu Y., and Wang J., High-chernnumber and high-temperature quantum Hall effect without landau levels, Natl. Sci. Rev. 7(8), 1280 (2020) https://doi.org/10.1093/nsr/nwaa089
32
F. Zhao Y., Zhang R., Mei R., J. Zhou L., Yi H., Q. Zhang Y., Yu J., Xiao R., Wang K., Samarth N., H. W. Chan M., X. Liu C., and Z. Chang C., Tuning the Chern number in quantum anomalous Hall insulators, Nature 588(7838), 419 (2020) https://doi.org/10.1038/s41586-020-3020-3
33
Li Y., Li J., Li Y., Ye M., Zheng F., Zhang Z., Fu J., Duan W., and Xu Y., High-temperature quantum anomalous Hall insulators in lithium-decorated iron-based superconductor materials, Phys. Rev. Lett. 125(8), 086401 (2020) https://doi.org/10.1103/PhysRevLett.125.086401
34
Huan H., Xue Y., Zhao B., Bao H., Liu L., and Yang Z., Tunable Weyl half-semimetals in two-dimensional iron-based materials MFeSe (M = Tl, In, Ga), Phys. Rev. B 106(12), 125404 (2022) https://doi.org/10.1103/PhysRevB.106.125404
35
Li Z., Han Y., and Qiao Z., Chern number tunable quantum anomalous Hall effect in monolayer transitional metal oxides via manipulating magnetization orientation, Phys. Rev. Lett. 129(3), 036801 (2022) https://doi.org/10.1103/PhysRevLett.129.036801
36
Jin L., R. Wang L., M. Zhang X., Liu Y., F. Dai X., L. Gao H., and D. Liu G., Fully spin-polarized Weyl fermions and in/out-of-plane quantum anomalous Hall effects in a two-dimensional d0 ferromagnet, Nanoscale 13(11), 5901 (2021) https://doi.org/10.1039/D0NR07556F
37
Wang K., Li Y., Mei H., Li P., and X. Guo Z., Quantum anomalous Hall and valley quantum anomalous Hall effects in two-dimensional d0 orbital XY monolayers, Phys. Rev. Mater. 6(4), 044202 (2022) https://doi.org/10.1103/PhysRevMaterials.6.044202
38
Li L., Kong X., Chen X., Li J., Sanyal B., and M. Peeters F., Monolayer 1T-LaN2: Dirac spin-gapless semiconductor of p-state and Chern insulator with a high Chern number, Appl. Phys. Lett. 117(14), 143101 (2020) https://doi.org/10.1063/5.0023531
39
D. Guo S., Q. Mu W., and G. Liu B., Valley-polarized quantum anomalous Hall insulator in monolayer RuBr2, 2D Mater. 9(3), 035011 (2022) https://doi.org/10.1088/2053-1583/ac687f
40
Feng X., Cai L., Chen Z., Dai Y., Huang B., and Niu C., Tunable second-order topological insulators in Chern insulators 2H-FeX2 (X = Cland Br), Appl. Phys. Lett. 122(19), 193104 (2023) https://doi.org/10.1063/5.0151542
41
Wu Y., Tong J., Deng L., Luo F., Tian F., Qin G., and Zhang X., Realizing spontaneous valley polarization and topological phase transitions in monolayer ScX2 (X = Cl, Br, I), Acta Mater. 246, 118731 (2023) https://doi.org/10.1016/j.actamat.2023.118731
42
L. Sheng X. and K. Nikolić B., Monolayer of the 5d transition metal trichloride OsCl3: A playground for two-dimensional magnetism, room-temperature quantum anomalous Hall effect, and topological phase transitions, Phys. Rev. B 95(20), 201402 (2017) https://doi.org/10.1103/PhysRevB.95.201402
43
He J., Li X., Lyu P., and Nachtigall P., Near-room-temperature Chern insulator and Dirac spin-gapless semiconductor: Nickel chloride monolayer, Nanoscale 9(6), 2246 (2017) https://doi.org/10.1039/C6NR08522A
44
D. Guo S., Q. Mu W., B. Xiao X., and G. Liu B., Intrinsic room-temperature piezoelectric quantum anomalous Hall insulator in Janus monolayer Fe2IX (X = Cl and Br), Nanoscale 13(30), 12956 (2021) https://doi.org/10.1039/D1NR02819G
45
Y. You J., Chen C., Zhang Z., L. Sheng X., A. Yang S., and Su G., Two-dimensional Weyl half-semimetal and tunable quantum anomalous Hall effect, Phys. Rev. B 100(6), 064408 (2019) https://doi.org/10.1103/PhysRevB.100.064408
46
Zhang H., Yang W., Cui P., Xu X., and Zhang Z., Prediction of monolayered ferromagnetic CrMnI6 as an intrinsic high-temperature quantum anomalous Hall system, Phys. Rev. B 102(11), 115413 (2020) https://doi.org/10.1103/PhysRevB.102.115413
47
Y. You J., Zhang Z., Gu B., and Su G., Two-dimensional room-temperature ferromagnetic semiconductors with quantum anomalous Hall effect, Phys. Rev. Appl. 12(2), 024063 (2019) https://doi.org/10.1103/PhysRevApplied.12.024063
48
Zhang B., Deng F., Chen X., Lv X., and Wang J., Quantum anomalous Hall effect in M2X3 honeycomb Kagome lattice, J. Phys. Condens. Matter 34(47), 475702 (2022) https://doi.org/10.1088/1361-648X/ac9502
49
P. Wang H., Luo W., and J. Xiang H., Prediction of high-temperature quantum anomalous Hall effect in two-dimensional transition-metal oxides, Phys. Rev. B 95(12), 125430 (2017) https://doi.org/10.1103/PhysRevB.95.125430
50
Li P. and X. Guo Z., The Dirac half-semimetal and quantum anomalous Hall effect in two-dimensional Janus Mn2X3Y3 (X, Y = F, Cl, Br, I), Phys. Chem. Chem. Phys. 23(35), 19673 (2021) https://doi.org/10.1039/D1CP02000E
51
Li P., Ma Y., Zhang Y., and X. Guo Z., Room temperature quantum anomalous Hall insulator in a honeycomb-Kagome lattice, Ta2O3, with huge magnetic anisotropy energy, ACS Appl. Electron. Mater. 3(4), 1826 (2021) https://doi.org/10.1021/acsaelm.1c00085
52
Aapro M., N. Huda M., Karthikeyan J., Kezilebieke S., C. Ganguli S., G. Herrero H., Huang X., Liljeroth P., and P. Komsa H., Synthesis and properties of monolayer MnSe with unusual atomic structure and antiferromagnetic ordering, ACS Nano 15(8), 13794 (2021) https://doi.org/10.1021/acsnano.1c05532
53
B. Goodenough J., Theory of the role of covalence in the perovskite-type manganites [La,M(II)]MnO3, Phys. Rev. 100(2), 564 (1955) https://doi.org/10.1103/PhysRev.100.564
Liu Z., Amani M., Najmaei S., Xu Q., Zou X., Zhou W., Yu T., Qiu C., G. Birdwell A., J. Crowne F., Vajtai R., I. Yakobson B., Xia Z., Dubey M., M. Ajayan P., and Lou J., Strain and structure heterogeneity in MoS2 atomic layers grown by chemical vapour deposition, Nat. Commun. 5(1), 5246 (2014) https://doi.org/10.1038/ncomms6246
59
H. Ahn G., Amani M., Rasool H., H. Lien D., P. Mastandrea J., W. III Ager J., Dubey M., C. Chrzan D., M. Minor A., and Javey A., Strain-engineered growth of two-dimensional materials, Nat. Commun. 8(1), 608 (2017) https://doi.org/10.1038/s41467-017-00516-5
60
Zhang C., Y. Li M., Tersoff J., Han Y., Su Y., J. Li L., A. Muller D., and K. Shih C., Strain distributions and their influence on electronic structures of WSe2‒MoS2 laterally strained heterojunctions, Nat. Nanotechnol. 13(2), 152 (2018) https://doi.org/10.1038/s41565-017-0022-x
61
Dai Z., Liu L., and Zhang Z., 2D materials: Strain engineering of 2D materials: Issues and opportunities at the interface, Adv. Mater 31(45), 1970322 (2019) https://doi.org/10.1002/adma.201970322
62
Li Z., Lv Y., Ren L., Li J., Kong L., Zeng Y., Tao Q., Wu R., Ma H., Zhao B., Wang D., Dang W., Chen K., Liao L., Duan X., Duan X., and Liu Y., Efficient strain modulation of 2D materials via polymer encapsulation, Nat. Commun. 11(2), 1151 (2020) https://doi.org/10.1038/s41467-020-15023-3