Dr. Bruce George Alexander Normand


Senior Scientist
Computational Physics Group >>
Building/Room: WHGA/133

Paul Scherrer Institut
Forschungsstrasse 111
5232 Villigen PSI

Research Interests

I am a theorist working in a wide range of fields within quantum magnetism. I apply analytical methods, provide phenomenological interpretations and interact very closely with colleagues performing experiments, preparing sample materials and developing and deploying advanced numerical methods. My research spans 

  • low-dimensional quantum magnets: spin ladders, spin chains and planar systems;
  • frustrated quantum magnetism: quantum spin liquids, many-particle bound states, proximate Kitaev systems;
  • quantum phase transitions: quantum criticality and dynamics,  first-order transitions and thermodynamics; 
  • quantum magnetophononics: nonequilibrium quantum many-body spin physics driven by the lattice phonons;
  • superconductors: both cuprates and iron-based materials.


Education: BA from Cambridge University (1985-88), PhD from MIT (1988-93)

Postdoc: University of Tokyo, ETH Zurich and University of Basel (1993-1999)

Research Assistant: Universities of Augsburg and Fribourg (2000-05)

Professor: Renmin University of China in Beijing (2010-16)

Senior Research Consultant: PSI (2017-19) and EPFL (2020-present)

Senior Staff Scientist:  PSI (2020-present)

Selected Publications

on quantum phase transitions, criticality and "Higgs" modes:

  • Field– and Pressure–Induced Magnetic Quantum Phase Transitions in TlCuCl3, M. Matsumoto, B. Normand, T. M. Rice and M. Sigrist, Phys. Rev. B 69, 054423 (2004).
  • Quantum Magnets under Pressure: Controlling Elementary Excitations in TlCuCl3, Ch. Rüegg, B. Normand, M. Matsumoto, A. Furrer, D. McMorrow, K. Krämer, H.–U. Güdel, S. Gvasaliya, H. Mutka and M. Boehm, Phys. Rev. Lett. 100, 205701 (2008).
  • Quantum and Classical Criticality in a Dimerized Quantum AntiferromagnetP. Merchant, B. Normand, K. W. Krämer, M. Boehm, D. F. McMorrow and Ch. Rüegg, Nature Physics 10, 373 (2014). 
  • Amplitude (Higgs) Mode in Three-Dimensional Dimerized Antiferromagnets, Y. Q. Qin, B. Normand, A. W. Sandvik and Z. Y. Meng, Phys. Rev. Lett. 118, 147207 (2017).

on quantum magnetism and exotic excited states:

  • Quantum Statistics of Interacting Dimer Spin Systems, Ch. Rüegg, B. Normand, M. Matsumoto, Ch. Niedermayer, A. Furrer, K. W. Krämer, H.–U. Güdel, Ph. Bourges, Y. Sidis and H. Mutka, Phys. Rev. Lett. 95, 267201 (2005).
  • Direct Observation of Magnon Fractionalization in the Quantum Spin Ladder, B. Thielemann, Ch. Rüegg, H. M. Rønnow, J.-S. Caux, A. M. Läuchli, B. Normand, D. Biner, K. W. Krämer, H.-U. Güdel, J. Stahn, S. N. Gvasaliya, K. Habicht, K. Kiefer, M. Boehm, D. F. McMorrow and J. Mesot, Phys. Rev. Lett. 102, 107204 (2009).
  • Giant Pressure-Dependence and Dimensionality Switching in a Metal-Organic Quantum Antiferromagnet, B. Wehinger, C. Fiolka, A. Lanza, R. Scatena, M. Kubus, A. Grockowiak, W. A. Coniglio, D. Graf, M. Skoulatos, J.-H. Chen, J. Gukelberger, N. Casati, O. Zaharko, P. Macchi, K. W. Krämer, S. Tozer, C. Mudry, B. Normand and Ch. Rüegg, Phys. Rev. Lett. 121, 117201 (2018).

on the kagome antiferromagnet and other frustrated models: 

  • Static Impurities in the Kagome Lattice: Dimer Freezing and Mutual Repulsion, S. Dommange, M. Mambrini, B. Normand and F. Mila, Phys. Rev. B 68, 224416 (2003).
  • Hubbard Model on the Pyrochlore Lattice: a 3D Quantum Spin LiquidB. Normand and Z. Nussinov, Phys. Rev. Lett. 112, 207202 (2014).
  • Gapless Spin-Liquid Ground State in the S = 1/2 Kagome Antiferromagnet, H. J. Liao, Z. Y. Xie, J. Chen, Z. Y. Liu, H. D. Xie, R. Z. Huang, B. Normand and T. Xiang, Phys. Rev. Lett. 118, 137202 (2017). 
  • Mermin-Wagner Physics, (H,T) Phase Diagram, and Candidate Quantum Spin-Liquid Phase in the Spin-1/2 Triangular-Lattice Antiferromagnet Ba8CoNb6O24Y. Cui, J. Dai, P. Zhou, P. S. Wang, T. R. Li, W. H. Song, L. Ma, Z. Zhang, S. Y. Li, G. M. Luke, B. Normand, T. Xiang and W. Yu, Phys. Rev. Mater. 2, 044403 (2018). 

on proximate Kitaev materials and models: 

  • Gapless Spin Excitations in the Field-Induced Quantum Spin-Liquid Phase of α-RuCl3, J. Zheng, K. Ran, T. Li, J. Wang, P. Wang, B. Liu, Z.-X. Liu, B. Normand, J. Wen and W. Yu, Phys. Rev. Lett. 119, 227208 (2017).
  • One Proximate Kitaev Spin Liquid in the K-J-Γ Model on the Honeycomb Lattice, J. Wang, B. Normand and Z.-X. Liu, Phys. Rev. Lett. 123, 197201 (2019).

on multiparticle bound states and first-order phase transitions: 

  • Multi-Triplet Bound States and Finite-Temperature Dynamics in Highly Frustrated Quantum Spin LaddersA. Honecker, F. Mila and B. Normand, Phys. Rev. B 94, 094402 (2016).
  • Thermal Critical Points and Quantum Critical End Point in the Frustrated Bilayer Heisenberg Antiferromagnet, J. Stapmanns, P. Corboz, F. Mila, A. Honecker, B. Normand and S. Wessel, Phys. Rev. Lett. 121, 127201 (2018).
  • Thermodynamic Properties of the Shastry-Sutherland Model throughout the Dimer-Product Phase, A. Wietek, P. Corboz, S. Wessel, B. Normand, F. Mila and A. Honecker, Phys. Rev. Res. 1, 033038 (2019).
  • A Quantum Magnetic Analogue to the Critical Point of Water, J. Larrea Jiménez, S. P. G. Crone, E. Fogh, M. Zayed, R. Lortz, E. Pomjakushina, K. Conder, A. M. Läuchli, L. Weber, S. Wessel, A. Honecker, B. Normand, Ch. Rüegg, P. Corboz, H. M. Rønnow and F. Mila, Nature 592, 370 (2021).

on cuprate superconductors:

  • Dynamic Susceptibility and Phonon Anomalies in the Bilayer t–J Model, B. Normand, H. Kohno and H. Fukuyama, J. Phys. Soc. Jpn. 64, 3903 (1995).
  • Microscopic Origin of Static Stripes in Cuprates, B. Normand and A. P. Kampf, Phys. Rev. B. 64, 024521 (2001).
  • Finite-Temperature Charge Dynamics and the Melting of the Mott InsulatorX. J. Han, C. Chen, J. Chen, H. D. Xie, R. Z. Huang, H. J. Liao, B. Normand, Z. Y. Meng and T. Xiang, Phys. Rev. B 99, 245150 (2019).

on iron-based superconductors:

  • Microscopic Coexistence of Superconductivity and Antiferromagnetism in Underdoped Ba(Fe1−xRux)2As2, L. Ma, G. F. Ji, J. Dai, X. R. Lu, M. J. Eom, J. S. Kim, B. Normand and W. Q. Yu, Phys. Rev. Lett. 109, 197002 (2012).
  • Simultaneous Optimization of Spin Fluctuations and Superconductivity under Pressure in an Iron-based Superconductor, G. F. Ji, J. S. Zhang, L. Ma, P. Fan, P. S. Wang, J. Dai, G. T. Tan, Y. Song, C. L. Zhang, P. C. Dai, B. Normand and W. Q. Yu, Phys. Rev. Lett. 111, 107004 (2013).
  • Phase Separation, Competition and Volume Fraction Control in NaFe1−xCoxAs, L. Ma, J. Dai, X. R. Lu, P. S. Wang, Y. Song, D. Hu, S. L. Li, P. C. Dai, C. L. Zhang, B. Normand and W. Q. Yu, Phys. Rev. B 90, 144502 (2014).

Further information ...

... and a complete publication list can be found on my personal website, brucenormand.weebly.com.