CONTACTS Photoemission spectroscopy group office: +86 (0)27 6875 8068

INFORMATION The institute for advanced studies, E-mail: nxu@whu.edu.cn

Wuhan University, 430072 Wuhan, China Research ID: N-3728-2016

EDUCATION 2007.9 – 2012.12

Ph. D., Condensed matter physics

Institute of Physics, Chinese Academy of Sciences (CAS), Beijing, China

Advisor: Prof. Hong Ding

2003.9 – 2007.7

B. S., Material physics

Harbin Institute of Technology, Harbin, China

ACADEMIC 2013.2-2014.9

CAREER Postdoc

Swiss Light Source (SLS), Paul Scherrer Institut (PSI), Villigen, Switzerland

2014.9-2017.9

Joint Postdoc

Swiss Light Source (SLS), Paul Scherrer Institut (PSI), Villigen, Switzerland/

École polytechnique fédérale de Lausanne (EPFL), Lausanne, Switzerland

2017.10-present

Professor

The institute for advanced studies, Wuhan University, Wuhan, China

HONORS AND IBM award in condensed matter physics, Swiss Physics Society, Switzerland (2017)

AWARD Thousand young overseas high-level talents award, Department of Organization, China (2017)

Hubei hundred young talents investigator award, Department of Organization of Hubei

province, China (2017)

Director’s scholarship, Institute of Physics CAS, China (2009, 2010)

Outstanding scholarship, Harbin Institute of Technology, China (2005)

First class scholarship, Harbin Institute of Technology, China (2004)

Excellent student, Harbin Institute of Technology, China (2004, 2005)

RESEARCH  2010.12-2012.1

EXPERIENCE Visiting Scholar

Brookhaven National Lab (BNL), Upton, New york, USA

Advisor: Prof. Peter Johnson

PUBLICATION (FIRST*-AUTHOR, CORRESPONDING^§-AUTHOR)

38. Extremely high magnetoresistance and conductivity in the type-II Weyl semimetals WP₂ and MoP₂

N. Kumar, Y. Sun, N. Xu, K. Manna, M. Yao, V. Süss, I. Leermakers, O. Young, T. Förster, M. Schmidt, H.

Borrmann, B. Yan, U. Zeitler, M. Shi, C. Felser, C. Shekhar

Nature Communications accepted (2017).

37. Distinct evolutions of Weyl fermion quasiparticles and Fermi arcs with bulk band topology in Weyl semimetals

N. Xu^§, G. Autes, C. E. Matt, B. Q. Lv, M. Y. Yao, F. Bisti, V. N. Strocov, D. Gawryluk, E. Pomjakushina, K. Conder, N. C. Plumb, M. Radovic, T. Qian, O. V. Yazyev, J. Mesot, H. Ding, and M. Shi^§

Physical Review Letters 118, 106406 (2017).

36. Observation of Weyl nodes and Fermi arcs in TaP

N. Xu*^§, H. M. Weng*, B. Q. Lv, C. Matt, J. Park, F. Bisti, V. N. Strocov, E. Pomjakushina, K. Conder, N. C. Plumb, M. Radovic, G. Autès, O. V. Yazyev, Z. Fang, X. Dai, G. Aeppli, T. Qian, J. Mesot, H. Ding^§, M. Shi^§

Nature Communications 7, 11006 (2016).

· See also Highlight by Paul Scherrer Institut: “New particle for future electronics” (2016).

· This article has been selected as “highly cited paper” by Web of Science (received enough citations to place in the top 1% of the Physics field).

Invited Review article:

35. Spin- and angle-resolved photoemission on the topological Kondo Insulator candidate: SmB₆

N. Xu^§, H. Ding^§, Ming Shi^§,

J. Phys.: Condens. Matter, 28 363001 (2016).

34. NaFe_0.56Cu_0.44As: A Pnictide Insulating Phase Induced by On-Site Coulomb Interaction

C. E. Matt, N. Xu, Baiqing Lv, Junzhang Ma, F. Bisti, J. Park, T. Shang, Chongde Cao, Yu Song, Andriy H. Nevidomskyy, Pengcheng Dai, L. Patthey, N. C. Plumb, M. Radovic, J. Mesot, and M. Shi,

Phys. Rev. Lett. 117, 097001 (2016).

33. Momentum-Resolved Electronic Structure of the High-Tc Superconductor Parent Compound BaBiO₃

N. C. Plumb, D. J. Gawryluk, Y. Wang, Z. Ristic, J. Park, B. Q. Lv, Z. Wang, C. E. Matt, N. Xu, T. Shang, K. Conder, J. Mesot, S. Johnston, M. Shi, and M. Radovic,

Phys. Rev. Lett. 117, 037002 (2016).

32. Angle-resolved photoemission observation of Mn-pnictide hybridization and negligible band structure renormalization in BaMn₂As₂ and BaMn₂Sb₂

W.-L. Zhang, P. Richard, A. van Roekeghem, S.-M. Nie, N. Xu, P. Zhang, H. Miao, S.-F. Wu, J.-X. Yin, B. B. Fu, L.-Y. Kong, T. Qian, Z.-J. Wang, Z. Fang, A. S. Sefat, S. Biermann, and H. Ding,

Phys. Rev. B 94, 155155 (2016).

31. Observation of Dirac-like band dispersion in LaAgSb₂

X. Shi, P. Richard, Kefeng Wang, M. Liu, C. E. Matt, N. Xu, R. S. Dhaka, Z. Ristic, T. Qian, Y.-F. Yang, C. Petrovic, M. Shi, H. Ding,

Phys. Rev. B 93, 081105(R) (2016).

30. Observation of Weyl nodes in TaAs

B. Q. Lv*, N. Xu*, H. M. Weng*, J. Z. Ma, P. Richard, X. C. Huang, L. X. Zhao, G. F. Chen, C. Matt, F. Bisti, V. Strokov, J. Mesot, Z. Fang, X. Dai, T. Qian^§, M. Shi^§, and H. Ding^§

Nature Physics 11, 724-727 (2015).

· This work is highlighted by EDITORIAL on Nature Physics: “After a Weyl”, Nature Physics 11, 697 (2015).

· This work is highlighted by Commentary on Nature Physics: “It's been a Weyl coming”, Nature Physics 11, 698 (2015).

· See also Research Highlight by Paul Scherrer Institut: “Electron’s cousin discovered after eighty-six-year search” (2015).

· This article has been selected as “Hot paper” by Web of Science (received enough citations to place in the top 0.1% of the Physics field).

29. Camelback-shaped band reconciles heavy electron behavior with weak electronic Coulomb correlations in superconducting TlNi₂Se₂

N. Xu^§, C. E. Matt, P. Richard, A. van Roekeghem, S. Biermann, X. Shi, S.-F. Wu, H. W. Liu, D. Chen, T. Qian, N. C. Plumb, M. Radovic, Hangdong Wang, Qianhui Mao, Jianhua Du, Minghu Fang, J. Mesot, H. Ding, and M. Shi^§,

Phys. Rev. B 92, 081116(R) (2015)

28 Observation of Fermi-Arc Spin Texture in TaAs

B. Q. Lv, S. Muff, T. Qian, Z. D. Song, S. M. Nie, N. Xu, P. Richard, C. E. Matt, N. C. Plumb, L. X. Zhao, G. F. Chen, Z. Fang, X. Dai, J. H. Dil, J. Mesot, M. Shi, H. M. Weng, and H. Ding,

Phys. Rev. Lett. 115, 217601 (2015).

27. Tuning the metal-insulator transition in NdNiO₃ heterostructures via Fermi surface instability and spin fluctuations

R. S. Dhaka, T. Das, N. C. Plumb, Z. Ristic, W. Kong, C. E. Matt, N. Xu, K. Dolui, E. Razzoli, M. Medarde, L. Patthey, M. Shi, M. Radovic, Joël Mesot,

Phys. Rev. B 92, 035127 (2015).

26. Direct spectroscopic evidence for completely filled Cu 3d shell in BaCu₂As₂ and α-BaCu₂Sb₂

S. F. Wu, P. Richard, A. van Roekeghem, S. M. Nie, H. Miao, N. Xu, T. Qian, B. Saparov, Z. Fang, S. Biermann, Athena S. Sefat, H. Ding,

Phys. Rev. B 91, 235109 (2015).

25. Dirac states with knobs on: Interplay of external parameters and the surface electronic properties of three-dimensional topological insulators

E. Frantzeskakis, N. de Jong, B. Zwartsenberg, T. V. Bay, Y. K. Huang, S. V. Ramankutty, A. Tytarenko, D. Wu, Y. Pan, S. Hollanders, M. Radovic, N. C. Plumb, N. Xu, M. Shi, C. Lupulescu, T. Arion, R. Ovsyannikov, A. Varykhalov, W. Eberhardt, A. de Visser, E. van Heumen, and M. S. Golden,

Phys. Rev. B 91, 205134 (2015)

24. High-temperature superconductivity from fine-tuning of Fermi-surface singularities in iron oxypnictides

A. Charnukha, D. V. Evtushinsky, C. E. Matt, N. Xu, M. Shi, B. Büchner, N. D. Zhigadlo, B. Batlogg, S. V. Borisenko,

Scientific reports 5, 18273 (2015).

23. Micro-metric electronic patterning of a topological band structure using a photon beam

E. Frantzeskakis, N. De Jong, B. Zwartsenberg, Y. K. Huang, T. V. Bay, P. Pronk, E. Van Heumen, D. Wu, Y. Pan, M. Radovic, N. C. Plumb, N. Xu, M. Shi, A. De Visser1 & M. S. Golden,

Scientific reports 5:16309 (2015).

22. Direct observation of the spin texture in SmB₆ as evidence of the topological Kondo insulator

N. Xu^§, P. K. Biswas, J. H. Dil, R. S. Dhaka, G. Landolt, S. Muff, C. E. Matt, X. Shi, N. C. Plumb, M. Radovic, E. Pomjakushina, K. Conder, A. Amato, S. V. Borisenko, R. Yu, H.-M. Weng, Z. Fang, X. Dai, J. Mesot, H. Ding, and M. Shi^§,

Nature Communications 5, 4566 (2014).

· This work is selected as Research highlights on Nature Physics: “The outsider” Nature Physics 10, 620 (2014).

· See also Highlight from Paul Scherrer Institut (PSI): “Insulator makes electrons move in an ordered way” (2014).

· See also Highlight from École polytechnique fédérale de Lausanne (EPFL): “Spin-based electronics: New material successfully tested” (2014).

· This article has been selected as “highly cited paper” by Web of Science (received enough citations to place in the top 1% of the Physics field).

21. Exotic Kondo crossover in a wide temperature region in the topological Kondo insulator SmB₆ revealed by high-resolution ARPES

N. Xu^§, C. E. Matt, E. Pomjakushina, X. Shi, R. S. Dhaka, N. C. Plumb, M. Radovic, P. K. Biswas, D. Evtushinsky, V. Zabolotnyy, J. H. Dil, K. Conder, J. Mesot, H. Ding, and M. Shi^§,

Phys. Rev. B 90, 085148 (2014).

20. Dynamical correlations and screened exchange on the experimental bench: spectral properties of the cobalt pnictide BaCo₂As₂

Ambroise van Roekeghem, Thomas Ayral, Jan M. Tomczak, Michele Casula, N. Xu, Hong Ding, Michel Ferrero, Olivier Parcollet, Hong Jiang, and Silke Biermann,

Phys. Rev. Lett. 113, 266403 (2014).

19. Correlation-Induced Self-Doping in the Iron-Pnictide Superconductor Ba₂Ti₂Fe₂As4O

J.-Z. Ma, A. van Roekeghem, P. Richard, Z.-H. Liu, H. Miao, L.-K. Zeng, N. Xu, M. Shi, C. Cao, J.-B. He, G.-F. Chen, Y.-L. Sun, G.-H. Cao, S.-C. Wang, S. Biermann, T. Qian, and H. Ding,

Phys. Rev. Lett. 113. 266407 (2014).

18. Structural phase transition induced by van Hove singularity in 5d transition metal compound IrTe₂

T. Qian, H. Miao, Z. J. Wang, X. Liu, X. Shi, Y. B. Huang, P. Zhang, N. Xu, P. Richard, M. Shi, M. H. Upton, J. P. Hill, G. Xu, X. Dai, Z. Fang, H. C. Lei, C. Petrovic, A. F. Fang, N. L. Wang, and H. Ding,

New J. Phys. 16, 123038 (2014).

17. Evolution from incoherent to coherent electronic states and its implications for superconductivity in FeTe_1−xSe_x

E. Ieki, K. Nakayama, Y. Miyata, T. Sato, H. Miao, N. Xu, X.-P. Wang, P. Zhang, T. Qian, P. Richard, Z.-J. Xu, J. S. Wen, G. D. Gu, H. Q. Luo, H.-H. Wen, H. Ding, and T. Takahashi,

Phys. Rev. B 89, 140506(R) (2014).

16. Observation of an electron band above the Fermi level in FeTe0.55Se0.45 from in-situ surface doping

P. Zhang, P. Richard, N. Xu, Y.-M. Xu, J. Ma, T. Qian, A. V. Fedorov, J. D. Denlinger, G. D. Gu, and H. Ding,

Appl. Phys. Lett. 105, 172601 (2014).

15. Angle-resolved photoemission spectroscopy observation of anomalous electronic states in EuFe₂As_2-xP_x

P. Richard, C. Capan, J. Ma, P. Zhang, N. Xu, T Tian, J.-D. Denlinger, G.-F. Chen, A.-S. Sefat, Z. Fisk and H. Ding,

J. Phys.: Condens. Matter 26 035702 (2014).

14. Observation of Strong-Coupling Pairing with Weakened Fermi-Surface Nesting at Optimal Hole Doping in Ca_{0. 33}Na_{0. 67}Fe₂As₂

Y.-B. Shi, Y.-B. Huang, J.-H. Wang, X.-P. Wang, X. Shi, A. van Roekeghem, W.-L Zhang, N. Xu, P. Richard, T. Qian, E. Rienks, S. Thirupathaiah, K. Zhao, C.-Q. Jin, M. Shi, H. Ding,

Chinese Physics Letters 31, 067403 (2014).

13. Electronic Band Structure of BaCo₂As₂: A Fully Doped Ferropnictide Analog with Reduced Electronic Correlations

N. Xu, P. Richard^§, A. van Roekeghem, P. Zhang, H. Miao, W.-L. Zhang, T. Qian, M. Ferrero, A. S. Sefat, S. Biermann, and H. Ding,

Phys. Rev. X 3, 011006 (2013).

12. Surface and bulk electronic structure of the strongly correlated system SmB₆ and implications for a topological Kondo insulator

N. Xu^§, X. Shi, P. K. Biswas, C. E. Matt, R. S. Dhaka, Y. Huang, N. C. Plumb, M. Radovic, J. H. Dil, E. Pomjakushina, K. Conder, A. Amato, Z. Salman, D. McK. Paul, J. Mesot, H. Ding, and M. Shi^§,

Phys. Rev. B 88, 121102(R) (2013).

· This work is selected as Editors' Suggestion.

· This article has been selected as “highly cited paper” by Web of Science (received enough citations to place in the top 1% of the Physics field).

11. Possible nodal superconducting gap and Lifshitz transition in heavily hole-doped Ba_0.1K_0.9Fe₂As₂

N. Xu^§, P. Richard^§, X. Shi, A. van Roekeghem, T. Qian, E. Razzoli, E. Rienks, G.-F. Chen, E. Ieki, K. Nakayama, T. Sato, T. Takahashi, M. Shi, and H. Ding^§,

Phys. Rev. B 88, 220508(R) (2013).

10. Angle-resolved photoemission observation of isotropic superconducting gaps in isovalent Ru-substituted Ba(Fe_0.75Ru_0.25)₂As₂

N. Xu, P. Richard^§, X.-P. Wang, X. Shi, A. van Roekeghem, T. Qian, E. Ieki, K. Nakayama, T. Sato, E. Rienks, S. Thirupathaiah, J. Xing, H.-H. Wen, M. Shi, T. Takahashi, and H. Ding^§,

Phys. Rev. B 87, 094513 (2013).

9. Experimental investigation of the electronic structure of Ca_0.83La_0.17Fe₂As₂

Y.-B. Huang, Y.-B. Shi, X.-P. Wang, X. Shi, P. Richard, J.-H. Wang, X.-P. Wang, X. Shi, N. Xu, Z. Wu, A. Li, J.-X. Yin, T. Qian, B. Lv, C. W. Chu, S. H. Pan, M. Shi, H. Ding,

Chinese Physics Letters 30, 017402 (2013).

8. Effects of Ru Substitution on Dimensionality and Electron Correlations in Ba(Fe_1−xRu_x)₂ As₂

N. Xu, T. Qian, P. Richard, Y.-B. Shi, X.-P. Wang, P. Zhang, Y.-B. Huang, Y.-M.Xu, H. Miao, G. Xu, G.-F. Xuan, W.-H. Jiao, Z.-A. Xu, G.-H. Cao, H. Ding^§,

Phys. Rev. B 86, 064505 (2012).

7. Orbital Characters Determined from Fermi Surface Intensity Patterns using Angle-Resolved Photoemission Spectroscopy

X.-P. Wang, P. Richard, Y.-B. Huang, H. Miao, L. Cevey, N. Xu, Y.-J. Sun, T. Qian, Y.-M. Xu, M. Shi, J.-P. Hu, X. Dai, and H. Ding,

Phys. Rev. B 85, 214518 (2012).

6 Three-dimensionality and orbital characters of Fermi surface in (Tl,Rb)_yFe_2−xSe₂

Z.-H. Liu, P. Richard, N. Xu, G. Xu, Y. Li, X.-C. Fang, L.-L. Jia, G.-F. Chen, D.-M. Wang, J.-B. He, T. Qian, J.-P. Hu, H. Ding, and S.-C. Wang,

Phys. Rev. Lett. 109, 037003 (2012).

5. Evolution of electronic structure upon Cu doping in the topological insulator Bi₂Se₃

Y. Tanaka, K. Nakayama, S. Souma, T. Sato, N. Xu, P. Zhang, P. Richard, H. Ding, Y. Suzuki, P. Das, K. Kadowaki, and T. Takahashi,

Phys. Rev. B 85, 125111 (2012).

4. Isotropic superconducting gaps with enhanced pairing on electron Fermi surfaces in FeTe_0.55Se_0.45

H. Miao, P. Richard, Y. Tanaka, K. Nakayama, T. Qian, K. Umezawa, T. Sato, Y.-M. Xu, Y. B. Shi, N. Xu, X.-P. Wang, P. Zhang, H.-B. Yang, Z.-J. Xu, J. S. Wen, G.-D. Gu, X. Dai, J.-P. Hu, T. Takahashi, and H. Ding,

Phys. Rev. B 85, 094506 (2012).

3. Orbital characters and near two-dimensionality of Fermi surfaces in NaFe_1-xCo_xAs

Z.-H. Liu, P. Richard, Y. Li, L.-L. Jia, G.-F. Chen, T.-L. Xia, D.-M. Wang, J.-B. He, H.-B. Yang, Z.-H. Pan, T. Valla, P. D. Johnson, N. Xu, H. Ding, and S.-C. Wang,

Appl. Phys. Lett. 101, 202601 (2012).

2. Unconventional superconducting gap in NaFe_0.95Co_0.05As observed by ARPES

Z.-H. Liu, P. Richard, K. Nakayama, G.-F. Chen, S. Dong, J.-B. He, D.-M. Wang, T.-L. Xia, K. Umezawa, T. Kawahara, S. Souma, T. Sato, T. Takahashi,T. Qian, Y.-B Huang, N. Xu, Y.-B Shi, H. Ding, and S.-C. Wang,

Phys. Rev. B 84, 064519 (2011).

1. Quasinested Fe orbitals versus Mott-insulating V orbitals in superconducting Sr₂VFeAsO₃ as seen from angle-resolved photoemission

T. Qian, N. Xu, Y.-B. Shi, K. Nakayama, P. Richard, T. Kawahara, T. Sato, T. Takahashi, M. Neupane, Y.-M. Xu, X.-P. Wang, G. Xu, X. Dai, Z. Fang,1 P. Cheng, H.-H. Wen, and H. Ding,

Phys. Rev. B 83, 140513 (R) (2011).

研究方向

Research Interests:

We are interested in probing and controlling electronic structures and emergent phenomena in novel quantum matter, including topological quantum materials, unconventional superconductors, two-dimensional (2D) materials, and strongly correlated systems.

Our previous studies have revealed remarkable electronic and topological properties in these novel materials, including

· Direct observations of bulk Weyl cones, surface Fermi arcs and their correspondence in transition-metal monophosphides as experimental evidences of the Weyl semimetal [1-3].

· Direct observations of the metallic surface state and its helical spin texture in SmB₆ as evidences of the topological Kondo insulator [4-6].

With further improvement in both experimental techniques and sample qualities, we aim at exploring more exotic quantum phenomena ranging from correlated topological semimetals to superconductors with unusual mechanism or non-trivial topological properties.

[1] B.Q.L*, N. Xu*, H.M.W* et. al., “Observation of Weyl nodes in TaAs.” Nature Physics 11, 724-727 (2015).

[2] N. Xu*^§, H.M.W* et. al., “Observation of Weyl nodes and Fermi arcs in TaP.” Nature Communications 7, 11006 (2016).

[3] N. Xu^§ et. al., Distinct evolutions of Weyl fermion quasiparticles and Fermi arcs with bulk band topology in Weyl semimetals. Physical Review Letters 118, 106406 (2017).

[4] N. Xu^§ et. al., “Surface and bulk electronic structure of the strongly correlated system SmB₆ and implications for a topological Kondo insulator.” Phys. Rev. B 88, 121102(R) (2013);

[5] N. Xu^§ et. al., “Direct observation of the spin texture in SmB₆ as evidence of the topological Kondo insulator.” Nature Communications 5, 4566 (2014).

[6] N. Xu^§ et. al., “Spin- and angle-resolved photoemission on the topological Kondo Insulator candidate: SmB₆”, J. Phys.: Condens. Matter, 28 363001 (2016). (Invited Review article)

(FIRST*-AUTHOR, CORRESPONDING^§-AUTHOR)

Experimental Techniques:

Our group primarily uses angle-resolved photoemission spectroscopy (ARPES) to discover and understand emerging phenomena in quantum materials.  Exploiting the advances in modern ARPES technology, we are going develop novel system that simultaneously achieves spin detection, energy tunability, polarization control, micrometer spatial resolution, and femtosecond temporal resolution. Such an ARPES, complemented by materials development and thin film growth, allows us to explore quantum phenomena with high selectivity and sensitivity, and dynamic behaviors with their natural time scales.

We also use other techniques at world-wide large scale facilities, for example muon spin rotation and relaxation (µSR), resonant inelastic x-ray scattering (RIXS), coherent diffraction imaging (CDI), x-ray magnetic circular dichroism (XMCD) and other x-ray techniques, to probe the electronic and magnetic structures in novel quantum matter.