Journal Home > Volume 14 , Issue 3
Nano Research 2021, 14(3): 834-839 https://doi.org/10.1007/s12274-020-3121-1
Research Article | Issue | Published: 01 March 2021

Large valley-polarized state in single-layer NbX2 (X = S, Se): Theoretical prediction

Show Author's Information Yanmei Zang,  Yandong Ma( ),  Rui Peng,  Hao Wang,  Baibiao Huang,  Ying Dai( )
School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Shandanan Street 27, Jinan 250100, China
Keywords:
first-principles, ferromagnetic, valley polarization, anomalous valley Hall effect, NbX2 (X = S, Se)
Topics:
CrystalsNiobium compoundsSelenium compoundsSpin orbit couplingVanadium compounds
Cite this article:
Zang Y, Ma Y, Peng R, et al. Large valley-polarized state in single-layer NbX2 (X = S, Se): Theoretical prediction. Nano Research, 2021, 14(3): 834-839. https://doi.org/10.1007/s12274-020-3121-1
Download citation
EndNote(RIS)
BibTeX

718

Views

74

Downloads

Citations

54

Crossref

0

WoS

46

Scopus

0

CSCD

Abstract Full text Electronic supplementary material About this article

Exploring two-dimensional valleytronic crystals with large valley-polarized state is of considerable importance due to the promising applications in next-generation information related devices. Here, we show first-principles evidence that single-layer NbX2 (X = S, Se) is potentially the long-sought two-dimensional valleytronic crystal. Specifically, the valley-polarized state is found to occur spontaneously in single-layer NbX2, without needing any external tuning, which arises from their intrinsic magnetic exchange interaction and inversion asymmetry. Moreover, the strong spin-orbit coupling strength within Nb-d orbitals renders their valley- polarized states being of remarkably large (NbS2 ~ 156 meV/NbSe2 ~ 219 meV), enabling practical utilization of their valley physics accessible. In additional, it is predicted that the valley physics (i.e., anomalous valley Hall effect) in single-layer NbX2 is switchable via applying moderate strain. These findings make single-layer NbX2 tantalizing candidates for realizing high-performance and controllable valleytronic devices.


menu
Abstract
Full text
Outline
Electronic supplementary material
About this article

Large valley-polarized state in single-layer NbX2 (X = S, Se): Theoretical prediction

Show Author's information Yanmei Zang, Yandong Ma( ), Rui Peng, Hao Wang, Baibiao Huang, Ying Dai( )
School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Shandanan Street 27, Jinan 250100, China

Abstract

Exploring two-dimensional valleytronic crystals with large valley-polarized state is of considerable importance due to the promising applications in next-generation information related devices. Here, we show first-principles evidence that single-layer NbX2 (X = S, Se) is potentially the long-sought two-dimensional valleytronic crystal. Specifically, the valley-polarized state is found to occur spontaneously in single-layer NbX2, without needing any external tuning, which arises from their intrinsic magnetic exchange interaction and inversion asymmetry. Moreover, the strong spin-orbit coupling strength within Nb-d orbitals renders their valley- polarized states being of remarkably large (NbS2 ~ 156 meV/NbSe2 ~ 219 meV), enabling practical utilization of their valley physics accessible. In additional, it is predicted that the valley physics (i.e., anomalous valley Hall effect) in single-layer NbX2 is switchable via applying moderate strain. These findings make single-layer NbX2 tantalizing candidates for realizing high-performance and controllable valleytronic devices.

Keywords: first-principles, ferromagnetic, valley polarization, anomalous valley Hall effect, NbX2 (X = S, Se)

References(68)

[1]
D. Xiao,; W. Yao,; Q. Niu, Valley-contrasting physics in graphene: Magnetic moment and topological transport. Phys. Rev. Lett. 2007, 99, 236809.
DOI Google Scholar
[2]
W. Yao,; D. Xiao,; Q. Niu, Valley-dependent optoelectronics from inversion symmetry breaking. Phys. Rev. B 2008, 77, 235406.
DOI Google Scholar
[3]
F. Zhang,; J. Jung,; G. A. Fiete,; Q. Niu,; A. H. MacDonald, Spontaneous quantum Hall states in chirally stacked few-layer graphene systems. Phys. Rev. Lett. 2011, 106, 156801.
DOI Google Scholar
[4]
Y. D. Ma,; L. Z. Kou,; A. J. Du,; B. B. Huang,; Y. Dai,; T. Heine, Conduction-band valley spin splitting in single-layer H-Tl2O. Phys. Rev. B 2018, 97, 035444.
DOI Google Scholar
[5]
D. Xiao,; G. B. Liu,; W. X. Feng,; X. D. Xu,; W. Yao, Coupled spin and valley physics in monolayers of MoS2 and other group-VI dichalcogenides. Phys. Rev. Lett. 2012, 108, 196802.
DOI Google Scholar
[6]
C. A. Lei,; Y. D. Ma,; T. Zhang,; X. L. Xu,; B. B. Huang,; Y. Dai, Valley polarization in monolayer CrX2 (X = S, Se) with magnetically doping and proximity coupling. New J. Phys. 2020, 22, 033002.
DOI Google Scholar
[7]
J. R. Schaibley,; H. Y. Yu,; G. Clark,; P. Rivera,; J. S. Ross,; K. L. Seyler,; W. Yao,; X. D. Xu, Valleytronics in 2D materials. Nat. Rev. Mater. 2016, 1, 16055.
DOI Google Scholar
[8]
Q. Pei,; B. Z. Zhou,; W. B. Mi,; C. Y. Cheng, Triferroic material and electrical control of valley degree of freedom. ACS Appl. Mater. Interfaces 2019, 11, 12675-12682
DOI Google Scholar
[9]
H. L. Zeng,; J. F. Dai,; W. Yao,; D. Xiao,; X. D. Cui, Valley polarization in MoS2 monolayers by optical pumping. Nat. Nanotechnol. 2012, 7, 490-493.
DOI Google Scholar
[10]
T. Cao,; G. Wang,; W. P. Han,; H. Q. Ye,; C. R. Zhu,; J. R. Shi,; Q. Niu,; P. H. Tan,; E. G. Wang,; B. L.; Liu, et al. Valley-selective circular dichroism of monolayer molybdenum disulphide. Nat. Commun. 2012, 3, 887.
DOI Google Scholar
[11]
P. Zhao,; Y. D. Ma,; C. A. Lei,; H. Wang,; B. B. Huang,; Y. Dai, Single-layer LaBr2: Two-dimensional valleytronic semiconductor with spontaneous spin and valley polarizations. Appl. Phys. Lett. 2019, 115, 261605.
DOI Google Scholar
[12]
K. F. Mak,; K. L. He,; J. Shan,; T. F. Heinz, Control of valley polarization in monolayer MoS2 by optical helicity. Nat. Nanotechnol. 2012, 7, 494-498.
DOI Google Scholar
[13]
N. Singh,; U. Schwingenschlogl, A route to permanent valley polarization in monolayer MoS2. Adv. Mater. 2017, 29, 1600970.
DOI Google Scholar
[14]
X. L. Xu,; Y. D. Ma,; T. Zhang,; C. A. Lei,; B. B. Huang,; Y. Dai, Nonmetal-atom-doping-induced valley polarization in single-layer Tl2O. J. Phys. Chem. Lett. 2019, 10, 4535-4541.
DOI Google Scholar
[15]
Q. Y. Zhang,; S. A. Yang,; W. B. Mi,; Y. C. Cheng,; U. Schwingenschlögl, Large spin-valley polarization in monolayer MoTe2 on top of EuO(111). Adv. Mater. 2016, 28, 959-966.
DOI Google Scholar
[16]
N. B. Li,; J. Y. Zhang,; Y. Xue,; T. Zhou,; Z. Q. Yang, Large valley polarization in monolayer MoTe2 on a magnetic substrate. Phys. Chem. Chem. Phys. 2018, 20, 3805-3812.
DOI Google Scholar
[17]
J. S. Qi,; X. Li,; Q. Niu,; J. Feng, Giant and tunable valley degeneracy splitting in MoTe2. Phys. Rev. B 2015, 92, 121403.
DOI Google Scholar
[18]
X. F. Ma,; L. Yin,; J. J. Zou,; W. B. Mi,; X. C. Wang, Strain-tailored valley polarization and magnetic anisotropy in two-dimensional 2H-VS2/Cr2C heterostructures. J. Phys. Chem. C 2019, 123, 17440-17448.
DOI Google Scholar
[19]
R. Peng,; Y. D. Ma,; S. Zhang,; B. B. Huang,; Y. Dai, Valley polarization in Janus single-layer MoSSe via magnetic doping. J. Phys. Chem. Lett. 2018, 9, 3612-3617.
DOI Google Scholar
[20]
T. C. Berkelbach,; M. S. Hybertsen,; D. R. Reichman, Theory of neutral and charged excitons in monolayer transition metal dichalcogenides. Phys. Rev. B 2013, 88, 045318.
DOI Google Scholar
[21]
H. Z. Lu,; W. Yao,; D. Xiao,; S. Q. Shen, Intervalley scattering and localization behaviors of spin-valley coupled Dirac fermions. Phys. Rev. Lett. 2013, 110, 016806.
DOI Google Scholar
[22]
O. L. Sanchez,; D. Ovchinnikov,; S. Misra,; A. Allain,; A. Kis, Valley polarization by spin injection in a light-emitting van der Waals heterojunction. Nano Lett. 2016, 16, 5792-5797.
DOI Google Scholar
[23]
C. M. Zhang,; Y. H. Nie,; S. Sanvito,; A. J. Du, First-principles prediction of a room-temperature ferromagnetic Janus VSSe monolayer with piezoelectricity, ferroelasticity, and large valley polarization. Nano Lett. 2019, 19, 1366-1370.
DOI Google Scholar
[24]
L. Z. Kou,; S. C. Wu,; C. Felser,; T. Frauenheim,; C. F. Chen,; B. H. Yan, Robust 2D topological insulators in van der Waals heterostructures. ACS Nano 2014, 8, 10448-10454.
DOI Google Scholar
[25]
L. Z. Kou,; B. H. Yan,; F. M. Hu,; S. C. Wu,; T. O. Wehling,; C. Felser,; C. F. Chen,; T. Frauenheim, Graphene-based topological insulator with an intrinsic bulk band gap above room temperature. Nano Lett. 2013, 13, 6251-6255.
DOI Google Scholar
[26]
L. Z. Kou,; F. M. Hu,; B. H. Yan,; T. Wehling,; C. Felser,; T. Frauenheim,; C. F. Chen, Proximity enhanced quantum spin Hall state in graphene. Carbon 2015, 87, 418-423.
DOI Google Scholar
[27]
D. MacNeill,; C. Heikes,; K. F. Mak,; Z. Anderson,; A. Kormányos,; V. Zólyomi,; J. Park,; D. C. Ralph, Breaking of valley degeneracy by magnetic field in monolayer MoSe2. Phys. Rev. Lett. 2015, 114, 037401.
DOI Google Scholar
[28]
Y. L. Li,; J. Ludwig,; T. Low,; A. Chernikov,; X. Cui,; G. Arefe,; Y. D. Kim,; A. M. Van Der Zande,; A. Rigosi,; H. M. Hill, et al. Valley splitting and polarization by the Zeeman effect in monolayer MoSe2. Phys. Rev. Lett. 2014, 113, 266804.
DOI Google Scholar
[29]
Y. J. Wu,; C. Shen,; Q. H. Tan,; J. Shi,; X. F. Liu,; Z. H. Wu,; J. Zhang,; P. H. Tan,; H. Z. Zheng, Valley Zeeman splitting of monolayer MoS2 probed by low-field magnetic circular dichroism spectroscopy at room temperature. Appl. Phys. Lett. 2018, 112, 153105.
DOI Google Scholar
[30]
B. Huang,; G. Clark,; E. Navarro-Moratalla,; D. R. Klein,; R. Cheng,; K. L. Seyler,; D. Zhong,; E. Schmidgall,; M. A. Mcguire,; D. H. Cobden, et al. Layer-dependent ferromagnetism in a van der Waals crystal down to the monolayer limit. Nature 2017, 546, 270-273.
DOI Google Scholar
[31]
C. Gong,; L. Li,; Z. L. Li,; H. W. Ji,; A. Stern,; Y. Xia,; T. Cao,; W. Bao,; C. Z. Wang,; Y. Wang, et al. Discovery of intrinsic ferromagnetism in two-dimensional van der Waals crystals. Nature 2017, 546, 265-269.
DOI Google Scholar
[32]
C. X. Huang,; J. S. Feng,; F. Wu,; D. Ahmed,; B. Huang,; H. J. Xiang,; K. M. Deng,; E. Kan, Toward intrinsic room-temperature ferromagnetism in two-dimensional semiconductors. J. Am. Chem. Soc. 2018, 140, 11519-11525.
DOI Google Scholar
[33]
N. H. Miao,; B. Xu,; L. G. Zhu,; J. Zhou,; Z. M. Sun, 2D intrinsic ferromagnets from van der Waals antiferromagnets. J. Am. Chem. Soc. 2018, 140, 2417-2420.
DOI Google Scholar
[34]
C. X. Huang,; Y. P. Du,; H. P. Wu,; H. J. Xiang,; K. M. Deng,; E. Kan, Prediction of intrinsic ferromagnetic ferroelectricity in a transition-metal halide monolayer. Phys. Rev. Lett. 2018, 120, 147601.
DOI Google Scholar
[35]
P. H. Jiang,; C. Wang,; D. C. Chen,; Z. C. Zhong,; Z. Yuan,; Z. Y. Lu,; W. Ji, Stacking tunable interlayer magnetism in bilayer CrI3. Phys. Rev. B 2019, 99, 144401.
DOI Google Scholar
[36]
W. Y. Tong,; S. J. Gong,; X. G. Wan,; C. G. Duan, Concepts of ferrovalley material and anomalous valley Hall effect. Nat. Commun. 2016, 7, 13612.
DOI Google Scholar
[37]
P. Zhao,; Y. D. Ma,; H. Wang,; B. B. Huang,; L. Z. Kou,; Y. Dai, Intrinsic valley polarization and anomalous valley Hall effect in single-layer 2H-FeCl2. arXiv: 2003.04561, 2020.
[38]
R. Peng,; Y. D. Ma,; X. L. Xu,; Z. L. He,; B. B. Huang,; Y. Dai, Intrinsic anomalous valley Hall effect in single-layer Nb3I8. Phys. Rev. B 2020, 102, 035412.
DOI Google Scholar
[39]
W. W. Zhao,; B. H. Dong,; Z. L. Guo,; G. Su,; R. J. Gao,; W. Wang,; L. X. Cao, Colloidal synthesis of VSe2 single-layer nanosheets as novel electrocatalysts for the hydrogen evolution reaction. Chem. Commun. 2016, 52, 9228-9231.
DOI Google Scholar
[40]
K. Krämer,; T. Schleid,; M. Schulze,; W. Urland,; G. Meyer, Three bromides of lanthanum: LaBr2, La2Br5, and LaBr3. Z. Anorg. Allg. Chem. 1989, 575, 61-70.
DOI Google Scholar
[41]
N. J. Doran,; D. J. Titterington,; B. Ricco,; G. Wexler, A tight binding fit to the bandstructure of 2H-NbSe2 and NbS2. J. Phys. C: Solid State Phys. 1978, 11, 685.
DOI Google Scholar
[42]
H. Wang,; X. W. Huang,; J. H. Lin,; J. Cui,; Y. Chen,; C. Zhu,; F. C. Liu,; Q. S. Zeng,; J. D. Zhou,; P. Yu, et al. High-quality monolayer superconductor NbSe2 grown by chemical vapour deposition. Nat. Commun. 2017, 8, 394.
DOI Google Scholar
[43]
X. J. Zhu,; Y. Q. Guo,; H. Cheng,; J. Dai,; X. D. An,; J. Y. Zhao,; K. Z. Tian,; S. Q. Wei,; X. C. Zeng,; C. Z. Wu, et al. Signature of coexistence of superconductivity and ferromagnetism in two- dimensional NbSe2 triggered by surface molecular adsorption. Nat. Commun. 2016, 7, 11210.
DOI Google Scholar
[44]
C. S. Lian,; C. Si,; W. H. Duan, Unveiling charge-density wave, superconductivity, and their competitive nature in two-dimensional NbSe2 Nano Lett. 2018, 18, 2924-2929.
DOI Google Scholar
[45]
R. Yan,; G. Khalsa,; B. T. Schaefer,; A. Jarjour,; S. Rouvimov,; K. C. Nowack,; H. G. Xing,; D. Jena, Thickness dependence of superconductivity in ultrathin NbS2 Appl. Phys. Express 2019, 12, 023008.
DOI Google Scholar
[46]
S. H. Zhao,; T. Hotta,; T. Koretsune,; K. Watanabe,; T. Taniguchi,; K. Sugawara, T. Takahashi,; H. Shinohara,; R. Kitaura, Two-dimensional metallic NbS2: Growth, optical identification and transport properties. 2D Mater. 2016, 3, 025027.
DOI Google Scholar
[47]
Y. D. Ma,; A. Kuc,; Y. Jing,; P. Philipsen,; T. Heine, Two-dimensional haeckelite NbS2: A diamagnetic high-mobility semiconductor with Nb4+ ions. Angew. Chem., Int. Ed. 2017, 56, 10214-10218.
DOI Google Scholar
[48]
Y. Xu,; X. F. Liu,; W. L. Guo, Tensile strain induced switching of magnetic states in NbSe2 and NbS2 single layers. Nanoscale 2014, 6, 12929-12933.
DOI Google Scholar
[49]
Y. J. Sun,; Z. W. Zhuo,; X. J. Wu, Bipolar magnetism in a two-dimensional NbS2 semiconductor with high curie temperature. J. Mater. Chem. C 2018, 6, 11401-11406.
DOI Google Scholar
[50]
Y. G. Zhou,; Z. G. Wang,; P. Yang,; X. T. Zu,; L. Yang,; X. Sun,; F. Gao, Tensile strain switched ferromagnetism in layered NbS2 and NbSe2 ACS Nano 2012, 6, 9727-9736.
DOI Google Scholar
[51]
Y. Wang,; M. Qiao,; Y. F. Li,; Z. F. Chen, A two-dimensional CaSi monolayer with quasi-planar pentacoordinate silicon. Nanoscale Horiz. 2018, 3, 327-334.
DOI Google Scholar
[52]
R. Peng,; Y. D. Ma,; B. B. Huang,; Y. Dai, Two-dimensional Janus PtSSe for photocatalytic water splitting under the visible or infrared light. J. Mater. Chem. A 2019, 7, 603-610.
DOI Google Scholar
[53]
Y. Ding,; Y. L. Wang, Density functional theory study of the silicene-like SiX and XSi3 (X = B, C, N, Al, P) honeycomb lattices: The various buckled structures and versatile electronic properties. J. Phys. Chem. C 2013, 117, 18266-18278.
DOI Google Scholar
[54]
E. Cadelano,; P. L. Palla,; S. Giordano,; L. Colombo, Elastic properties of hydrogenated graphene. Phys. Rev. B 2010, 82, 235414.
DOI Google Scholar
[55]
R. Peng,; Y. D. Ma,; Z. L. He,; B. B. Huang,; L. Z. Kou,; Y. Dai, Single-layer Ag2S: A two-dimensional bidirectional auxetic semiconductor. Nano Lett. 2019, 19, 1227-1233.
DOI Google Scholar
[56]
R. C. Andrew,; R. E. Mapasha,; A. M. Ukpong,; N. Chetty, Mechanical properties of graphene and boronitrene. Phys. Rev. B 2012, 85, 125428.
DOI Google Scholar
[57]
K. H. Michel,; B. Verberck, Theory of elastic and piezoelectric effects in two-dimensional hexagonal boron nitride. Phys. Rev. B 2009, 80, 224301.
DOI Google Scholar
[58]
Z. B. Gao,; X. Dong,; N. B. Li,; J. Ren, Novel two-dimensional silicon dioxide with in-plane negative Poisson’s ratio. Nano Lett. 2017, 17, 772-777.
DOI Google Scholar
[59]
C. Gong,; H. J. Zhang,; W. H. Wang,; L. Colombo,; R. M. Wallace,; K. Cho, Band alignment of two-dimensional transition metal dichalcogenides: Application in tunnel field effect transistors. Appl. Phys. Lett. 2013, 103, 053513.
DOI Google Scholar
[60]
D. J. Thouless,; M. Kohmoto,; M. P. Nightingale,; M. den Nijs, Quantized Hall conductance in a two-dimensional periodic potential. Phys. Rev. Lett. 1982, 49, 405-408.
DOI Google Scholar
[61]
G. Kresse,; J. Furthmüller, Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. Phys. Rev. B 1996, 54, 11169-11186.
DOI Google Scholar
[62]
G. Kresse,; J. Furthmüller, Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set. Comput. Mater. Sci. 1996, 6, 15-50.
DOI Google Scholar
[63]
H. J Monkhorst,; J. D. Pack, Special points for Brillouin-zone integrations. Phys. Rev. B 1976, 13, 5188-5192.
DOI Google Scholar
[64]
J. P. Perdew,; K. Burke,; M. Ernzerhof, Generalized gradient approximation made simple. Phys. Rev. Lett. 1996, 77, 3865.
DOI Google Scholar
[65]
G. Kresse,; D. Joubert, From ultrasoft pseudopotentials to the projector augmented-wave method. Phys. Rev. B 1999, 59, 1758-1775.
DOI Google Scholar
[66]
J. Heyd,; G. E. Scuseria,; M. Ernzerhof, Hybrid functionals based on a screened Coulomb potential. J. Chem. Phys. 2003, 118, 8207-8215.
DOI Google Scholar
[67]
A. Togo,; F. Oba,; I. Tanaka, First-principles calculations of the ferroelastic transition between rutile-type and CaCl2-type SiO2 at high pressures. Phys. Rev. B 2008, 78, 134106.
DOI Google Scholar
[68]
A. A. Mostofi,; J. R. Yates,; Y. S. Lee,; I. Souza,; D. Vanderbilt,; N. Marzari, wannier90: A tool for obtaining maximally-localised Wannier functions. Comput. Phys. Commun. 2008, 178, 685-699.
DOI Google Scholar
File
12274_2020_3121_MOESM1_ESM.pdf (3.1 MB)
Publication history
Copyright
Acknowledgements

Publication history

Received: 16 July 2020
Revised: 24 August 2020
Accepted: 15 September 2020
Published: 01 March 2021
Issue date: March 2021

Copyright

© Tsinghua University Press and Springer-Verlag GmbH Germany, part of Springer Nature

Acknowledgements

This work is supported by the National Natural Science Foundation of China (No. 11804190), Shandong Provincial Natural Science Foundation of China (Nos. ZR2019QA011 and ZR2019MEM013), Shandong Provincial Key Research and Development Program (Major Scientific and Technological Innovation Project) (No. 2019JZZY010302), Shandong Provincial Key Research and Development Program (No. 2019RKE27004), Qilu Young Scholar Program of Shandong University, and Taishan Scholar Program of Shandong Province.

Return