Jianhui Xu

Jianhui Xu

PhD in Physics

Jianhui Xu (许建辉)

Senior Researcher, RWTH Aachen University

My name is Jianhui Xu, [Jyen Hway Shoo]. It is Chinese name, natively written as 许建辉. I was born and grew up in China, and moved to Germany in 2013.

Currently, I am a senior researcher with extensive experience in experimental design and data modeling and analysis, currently affiliated with RWTH Aachen University. I hold a Ph.D. in Physics from the Technical University Berlin and have previously worked at Helmholtz-Zentrum Berlin for Materials and Energy, where I was recognized with a Performance Premium Award, and Technical University München.

Scientific Research

My research focuses on uncovering novel quantum phenomena in magnetic materials, blending experimental and theoretical approaches. I design and conduct sophisticated experiments and leverage advanced data analysis and computational techniques, including mean field theory, Monte Carlo simulations, and machine learning. For instance, my work on Nd2Zr2O7 uncovered the quantum spin ice state and Higgs transition, demonstrating my ability to solve complex problems and generate impactful insights Publication Blog.

Data Science

My passion for data science stems from my extensive experience in research and my fascination with uncovering insights from both trivial and complex data. During my academic career, I have consistently applied advanced data analysis and computational techniques to solve complex problems in quantum material investigations. This experience has solidified my belief in the power of data to drive innovation and discovery. To further my knowledge, I have completed several machine learning courses as well. I am eager to leverage my analytical abilities and technical expertise to tackle real-world challenges.

Projects

  1. Optimization via exhaustive fitting to four-dimensional 100+ GB data Publication
    • Extract signals: background estimation, slicing and signal detection automatically
    • Fit to highly nonlinear quantum model
  2. Identification of local patterns on a grid of correlated vectors Blog
    • Nonlinear-model fit to experimental data extracting vector configurations
    • Unsupervised machine learning correlation patterns (Principal component analysis and K-Means)
    • General statistical analyses of the vector directions and identify local patterns and their correlation lengths
  3. Monte Carlo study of spacial-temporal dynamical correlations Publication Blog
    • Find the ground state of a system using simulated annealing and parallel tempering
    • Generating time-series data of vector configurations by integrating equation of motion using adaptive Runge-Kutta methods
    • Fast numerical spacial-temporal Fourier transformations
  4. Mean field modeling of a frustrated magnetic system Blog
    • Fourier transformation of interactions on a periodic lattice
    • Solve eigen problems
    • Calculate observables and compare to measured data

Courses

  1. Machine learning (Stanford University) (24 hours)Certificate
    • Covered: Regression, Neural network, SVM, PCA, K-Means
  2. Deep learning specialist (Stanford University) (125 hours)Specialization Certificate, including 5 courses:
  3. Databases and SQL for data science (IBM) (20 hours)Certificate
  4. Course projects：
    • Hand-written number recognition
    • Face recognition
    • Neural style transfer
    • Natural language processing using Keras and Tensorflow

Awards and Highlights

  • Performance Premium: Helmholtz-Zentrum Berlin, Germany (2019)
  • Chenhuxiong Scholarship (top 20%): Peking University, China (2012)
  • National Scholarship (top 5%): Shanxi Datong University, China (2018)
  • Journal Papers: 29, including Nature Physics, Science Advances, Physical Review Letters.
  • Total citations: 671+, h-index: 15 Google Scholar

Public Speaking

  1. 2023, Talk, Joint European Magnetic Symposia 2023, Madrid, Spain.
  2. 2022, Invited talk, LLB-MLZ workshop, Paris, France.
  3. 2022, Talk, MORIS user workshop, Munich, Germany.
  4. 2021, Invited talk, Neutron optics group meeting at Heinz Maier-Leibnitz Zentrum, Germany.
  5. 2021, Invited talk, Seminar at the optical condensed matter group, Cologne University, Germany.
  6. 2020, Invited talk, Augusburg Univeristy, Germany.
  7. 2020, Talk, MLZ user Meetings 2020 (online), Garching, Germany.
  8. 2019, Invited talk, Quantum phenomena group meeting at Heinz Maier-Leibnitz Zentrum, Germany.
  9. 2018, Talk, DPG Spring Meetings 2018, Berlin, Germany.
  10. 2015, Invited talk, Seminar at Center for Applied Magnetism, Peking University, Beijing, China.
  11. 2012, Talk, 12th Panalytical China User Club Meeting, Hangzhou, China.

Publications

  1. X. Wang, F. Zhu, X. Yang, M. Meven, X. Mi, C. Yi, J. Song, T. Müller, W. Schmidt, K. Schmalzl, E. Ressouche, Jianhui Xu, M. He, Y. Shi, W. Feng, Y. Mokrousov, S. Blügel, G. Roth, T. Brückel, and Y. Su,
    Flat band-engineered spin-density wave in the correlated topological semimetal Mn3Sn , arXiv:2306.04312.
  2. E. Babcock, Z. Salhi, A. Feoktystov, L. J. Bannenberg, S. R. Parnell, D. Alba Venero, V. Hutanu, H. Thoma, Jianhui Xu, P. Pistel, J. Damean, A. Ioffe, S. Mattauch,
    In-situ 3He neutron spin filters at JCNS, status and updates, J. Phys.: Conf. Ser. 2481 012009 (2022).
  3. A. Samartzis, Jianhui Xu, V. K. Anand, A. T. M. N. Islam, J. Ollivier, Y. Su, B. Lake,
    Pinch points and half-moons in dipolar-octupolar Nd2Hf2O7 , Phys. Rev. B 106, L100401(2022).
  4. Jianhui Xu, M. Atterving, M. Skoulatos, A. Ostermann, R. Georgii, T. Keller, and P. Böni,
    Design of a Neutron Polarizing Bender for a Cold Triple-Axis Spectrometer , Nuc. Inst. Methods A 1031, 166526 (2022).
  5. H. Trepka, T. Keller, M. Krautloher, Jianhui Xu, K. Habicht, M. Böhm, B. Keimer, and M. Hepting,
    Critical magnetic fluctuations in the layered ruthenates Ca2RuO4 and Ca3Ru2O7 , Phys. Rev. Research 4, 023181 (2022).
  6. F. Landolt, Z. Yan, S. Gvasaliya, K. Beauvois, E. Ressouche, Jianhui Xu, A. Zheludev,
    Phase diagram and spin waves in the frustrated ferro-antiferromagnet SrZnVO(PO4)2, Phys. Rev. B 104, 224435 (2021).
  7. Yayuan Qin, Yao Shen, Changle Liu, Hongliang Wo, Yonghao Gao, Yu Feng, Xiaowen Zhang, Gaofeng Ding, Yiqing Gu, Qisi Wang, Shoudong Shen, Helen C. Walker, Robert Bewley, Jianhui Xu, Martin Boehm, Paul Steffens, Seiko Ohira-Kawamura, Naoki Murai, Astrid Schneidewind, Xin Tong, Gang Chen, Jun Zhao,
    Field-Tuned Quantum Effects in a Triangular-Lattice Ising Magnet, Science Bulletin 2021.
  8. S. E. Nikitin, A. Podlesnyak, Jianhui Xu, D. Voneshen, M. Duc Le, S. L. Bud'ko, P. C. Canfield, D. A. Sokolov,
    Magnetic field-induced softening of spin waves and hard-axis order in Kondo-lattice ferromagnet CeAgSb2, Phys. Rev. B 104, 115169 (2021).
  9. Fengfeng Zhu, Lichuan Zhang, Xiao Wang, Flaviano José dos Santos, Junda Song, Thomas Müller, Karin Schmalzl, Wolfgang F. Schmidt, Alexandre Ivanov, Jitae T. Park, Jianhui Xu, Jie Ma, Samir Lounis, Stefan Blügel, Yuriy Mokrousov, Yixi Su, Thomas Brückel,
    Topological magnon insulators in two-dimensional van der Waals ferromagnets CrSiTe3 and CrGeTe3: towards intrinsic gap-tunability, Sci. Adv. 7, eabi7532(2021).
  10. S. E. Nikitin, S. Nishimoto, Y. Fan, J. Wu, L. S. Wu, A. S. Sukhanov, M. Brando, N. S. Pavlovskii, Jianhui Xu, L. Vasylechko, R. Yu, A. Podlesnyak,
    Multiple fermion scattering in the weakly coupled spin-chain compound YbAlO3, Nat. Commun. 12, 3599 (2021).
  11. P. Y. Portnichenko, A. Akbari, S. E. Nikitin, A. S. Cameron, A. V. Dukhnenko, V. B. Filipov, N. Yu. Shitsevalova, P. Cermak, I. Radelytskyi, A. Schneidewind, J. Ollivier, A. Podlesnyak, Z. Huesges, Jianhui Xu, A. Ivanov, Y. Sidis, S. Petit, J.-M. Mignot, P. Thalmeier, D. S. Inosov,
    Field-angle resolved magnetic excitations as a probe of hidden-order symmetry in CeB6, Phys. Rev. X 10, 021010 (2020).
  12. Anup Kumar Bera, Jianda Wu, Wang Yang, Robert Bewley, Martin Boehm, Jianhui Xu, Maciej Bartkowiak, Oleksandr Prokhnenko, Bastian Klemke, A. T. M. Nazmul Islam, JosephMathew Law, Zhe Wang and Bella Lake,
    Dispersions of Many-Body Bethe Strings, Nature Physics, 1-6 (2020).
  13. Jianhui Xu, Owen Benton, V. K. Anand, A. T. M. N. Islam, T. Guidi, G. Ehlers, and B. Lake,
    Order out of Coulomb phase and Higgs transition: frustrated transverse interactions of Nd2Zr2O7, Phys. Rev. Lett. 124, 097203 (2020).
  14. V. K. Bhartiya, K. Yu. Povarov, D. Blosser, S. Bettler, Z. Yan, S. Gvasaliya, S. Raymond, E. Ressouche, K. Beauvois, Jianhui Xu, F. Yokaichiya, A. Zheludev
    Presaturation phase with no dipolar order in a quantum ferro-antiferromagnet, Phys. Rev. Res., 1, 033078 (2019).
  15. Jianhui Xu, Owen Benton, V. K. Anand,\ A. T. M. N. Islam, T. Guidi, G. Ehlers, E. Feng, Y. Su, A. Sakai, P. Gegenwart, and B. Lake,
    Anisotropic exchange Hamiltonian, magnetic phase diagram and domain inversion of Nd2Zr2O7, Phys. Rev. B 99, 144420 (2019).
  16. V. K. Anand, L. Opherden, Jianhui Xu, D. T. Adroja, A. D. Hillier, P. K. Biswas, T. Herrmannsdörfer, M. Uhlarz, J. Hornung, J. Wosnitza, E. Canévet, and B. Lake,
    Evidence for a dynamical ground state in the frustrated pyrohafnate Tb2Hf2O7, Phys. Rev. B 97, 094402 (2018).
  17. T. Watanabe, S. Kobayashi, Y. Hara, Jianhui Xu, B. Lake, J-Q Yan, A. Niazi, D.C. Johnston,
    Orbital- and spin-driven lattice instabilities in quasi-one-dimensional CaV2O4, Phys. Rev. B 98, 094427 (2018)}.
  18. Jianhui Xu, A. T. M. N. Islam, I. N. Glavatskyy, M. Reehuis, Jens-Uwe Hoffmann, and B. Lake,
    Field-induced quantum spin-1/2 chains and disorder in Nd2Zr2O7, Phys. Rev. B 98(R), 060408 (2018).
  19. V. K. Anand, A. T. M. N. Islam, A. Samartzis, Jianhui Xu, N. Casati, B. Lake,
    Optimization of single crystal growth of candidate quantum spin-ice Pr2Hf2O7 by optical floating-zone method, Journal of Crystal Growth 498, 124 (2018).
  20. L. Opherden, J. Hornung, T. Herrmannsdörfer, Jianhui Xu, A. T. M. N. Islam, B. Lake, and J. Wosnitza,
    Evolution of antiferromagnetic domains in the all-in-all-out ordered pyrochlore Nd2Zr2O7, Phys. Rev. B 95, 184418 (2017).
  21. V. K. Anand, L. Opherden, Jianhui Xu, D. T. Adroja, A. T. M. N. Islam, T. Herrmannsdörfer, J. Hornung, R. Schönemann, M. Uhlarz, H. C. Walker, N. Casati, and B. Lake,
    Physical properties of the candidate quantum spin-ice system Pr2Hf2O7, Phys. Rev. B 94, 144415 (2016)}.
  22. Jianhui Xu, C. Balz, C. Baines, H. Luetkens, and B. Lake,
    Spin dynamics of the ordered dipolar-octupolar pseudospin-1/2 pyrochlore Nd2Zr2O7 probed by muon spin relaxation, Phys. Rev. B 94, 064425 (2016).
  23. Jianhui Xu, V. K. Anand, A. K. Bera, M. Frontzek, D. L. Abernathy, N. Casati, K. Siemensmeyer, and B. Lake,
    Magnetic structure and crystal-field states of the pyrochlore antiferromagnet Nd2Zr2O7, Phys. Rev. B 92, 224430 (2015)}.
  24. V. K. Anand, A. K. Bera, Jianhui Xu, T. Herrmannsdörfer, C. Ritter, and B. Lake,
    Observation of long-range magnetic ordering in pyrohafnate Nd2Hf2O7: A neutron diffraction study, Phys. Rev. B 92, 184418 (2015).
  25. Jianhui Xu, W. Yang, Q. Du, Y. Xia, H. Du, J. Yang, C. Wang, J. Han, S. Liu, Y. Zhang and Y. Yang,
    Wide temperature span of entropy change in first-order metamagnetic MnCo1-xFexSi, J. Phys. D: Appl. Phys. 47, 065003 (2014).
  26. Jianhui Xu, X. Liu, Y. Xia, W. Yang, H. Du, J. Yang, Y. Zhang, Y. Yang,
    Magnetic properties and magnetocaloric effect of (Mn1-xFex)5Sn3 (x=0–0.5) compounds, J. Appl. Phys. 113, 17A921 (2013).
  27. Jianhui Xu, Y. Xia, W. Yang, H. Du, J. Yang, C. Wang, J. Han, S. Liu, Y. Yang,
    The evolution of the magnetic phases of Sb-doped Mn5Sn3 compounds, J. Appl. Phys., 113, 17E111 (2013).
  28. Yuanhua Xia, Honglin Du, Jianhui Xu, Yan Zhang, Changsheng Wang, Jinbo Yang, Xiangzhen Han, Kai Sun,
    Crystal structure and magnetic properties of DyCuxGa2-x (x = 0-2) antiferromagnetic compounds, J. Alloys Compd., 512(1), 212 (2012).
  29. Yuanhua Xia, Honglin Du, Jianhui Xu, Yan Zhang, Changsheng Wang, Jingzhi Han, Shunquan Liu, Qing Xu, Jinbo Yang,
    The magnetic and magnetocaloric properties of NdFe12-xMox compounds, J. Appl. Phys., 111(7), 07A949 (2012).