Michel Gingras

Office: PHY 364

Phone: (519) 888-4567 ext. 35697

Email: gingras@uwaterloo.ca

Research interests

• Condensed matter theory
• Statistical mechanics

Present research activities

My interests span several areas of statistical mechanics and condensed matter physics. I hold the Tier 1 Canada Research Chair in statistical mechanics and condensed matter physics at the University of Waterloo and was awarded a Steacie Fellowship from NSERC for my work in this area. I was awarded a 2012 Killam Fellowship, the 2001 Herzberg Medal (CAP) and the 2009 Brockhouse Medal (CAP). I am a associate member of the Quantum Materials Program of the Canadian Institute for Advanced Research (CIFAR).

My main current interests are in the area of random disordered systems and problems pertaining to frustrated classical and quantum magnetic systems. I often collaborate with experimentalists, either trying to understand their results or to think of new experiments to test theoretical ideas.

The number of students and post-docs in my group varies with time between 3-4 graduate students and a couple of post-docs. I will be interested in taking graduate students starting Fall 2008.

Research areas

(a) Random Disorder in Condensed Matter Physics: All real materials contain a certain amount of frozen (quenched) random disorder such as impurities or vacancies. Other materials, such as amorphous metallic glasses, are completely random. The main questions of interest in this area of research are: how does the presence of weak random disorder affect the thermodynamic properties of real materials, what type of phases do they exhibit, and what are their low-temperature physical properties? Sometimes a small amount of disorder can have dramatic effects on the thermodynamic behaviour of a material. For example, there is now strong experimental and theoretical evidence that weak disorder leads to novel and exotic types of superconducting vortex-glass phases in the mixed state of high-temperature cuprate superconductors. The study via numerical and analytical methods of the effects of random disorder on magnetic, superconducting and molecular systems constitutes one of my main research interests. Students and post-docs working in the quantum matters group have access to a dedicated computing serial farm for numerical studies.

(b) Frustrated Antiferromagnets: Frustration arises when a magnetic system cannot minimize its total classical ground state energy by minimizing the energy of each pair of spin-spin interaction individually. For example, this arises for antiferromagnetically coupled spins on triangular and face-centered cubic lattices. The phenomenon of frustration is an ubiquitous one in condensed matter physics. It arises in magnetic systems, molecular crystals, superconducting Josephson junction arrays. There is an enormous amount of current research devoted to the study of strongly frustrated antiferromagnets since it has been suggested that these could exhibit novel non-Néel ground states with zero staggered sublattice magnetization. However, intriguing experimental results find that a large portion of the materials studied show a magnetic spin-freezing transition similar to what is found in highly disordered magnetic materials, The origin of this spin-freezing constitutes a major puzzle in this field: is the freezing intrinsic to the idealized pure material, or is it driven by the weak amount of random impurities at the 1% level? Also, what is the combined effect of random disorder and quantum fluctuations in these systems? Which one of random disorder or quantum fluctuations "wins"? These are some of the questions that I am interested in this exciting topical research area. In the past few years, I have been quite active in understanding a new class of magnetic systems known as spin ices. These constitute a novel type of systems where the behavior of the magnetic moments is akin to that of the frozen-in proton disorder in the common phase of water ice, hence the name spin ice. They display a plethora of interesting behaviors. Most interestingly, it has proved possible to make close contact between theory and experiments on spin ice systems.

Selected publications

• Martin Weigel and Michel J.P. Gingras.
  Nature of the Zero-Temperature Phase of the Planar Spin Glass in Two Dimensions.
  To appear in Phys. Rev. B. [Abstract].
• S. M. A. Tabei, F. Vernay and M. J. P. Gingras.
  Effective Spin-1/2 Description of Transverse-Field-Induced Random Fields in Dipolar Spin Glasses with Strong Single-Ion Anisotropy.
  To appear in Phys. Rev. B [2007]. [Abstract].
• J.A. Quilliam, K.A. Ross, A.G. Del Maestro, M.J.P. Gingras, L.R. Corruccini and J.B. Kycia.
  Evidence for Gapped Spin-Wave Excitations in the Frustrated Gd2Sn2O7 Pyrochlore Antiferromagnet From Low-Temperature Specific Heat Measurements.
  Phys. Rev. Lett. 99, 097201 (2007). [Abstract].
• Adrian Del Maestro and Michel J.P. Gingras.
  Low Temperature Specific Heat And Possible Gap to Magnetic Excitations in the Heisenberg Pyrochlore Antiferromagnet Gd2Sn207.
  Phys. Rev. B 76, 064418 (2007) [Abstract].
• Taras Yavors'kii, Michel J.P. Gingras and Matthew Enjalran.
  Ill-Behaved Convergence of a Model of the Gd3Ga5O12 Garnet Antiferromagnet with Truncated Magnetic Dipole-Dipole Interactions.
  J. Phys.: Condens. Matter 19, 145274 (2007). [Abstract].
• Hamid R. Molavian, Michel J.P. Gingras and Benjamin Canals.
  Dynamically-Induced Frustration as a Route to a Quantum Spin Ice State in Tb2Ti2O7 via Virtual Crystal Field Excitations and Quantum Many-Body Effects.
  Phys. Rev. Lett. 98, 157204 (2007). [Abstract].
• Martin Weigel and Michel J.P. Gingras.
  Spin and Chiral Stiffness of the XY spin Glass in Two Dimensions.
  J. Phys.: Condens. Matter 19, 145217 (2007). [Abstract].
• F. Vernay, T.P. Devereaux and M.J.P. Gingras.
  Raman Scattering for Triangular Lattices Spin-1/2 Heisenberg Antiferromagnets.
  J. Phys.: Condens. Matter 19, 145243 (2007). [Abstract].
• S.M.A. Tabei, M.J.P. Gingras, Y.-J. Kao, P. Stasiak and J.-Y. Fortin.
  Induced Random Fields in the LiHoxY1-xF4 Quantum Ising Magnet in a Transverse Magnetic Field.
  Phys. Rev. Lett. 97, 237203 (2006). [Abstract].
• Taras Yavors'kii, Matthew Enjalran and Michel J.P. Gingras.
  Spin Hamiltonian, Competing Small Energy Scales and Incommensurate Long Range Order in the Highly Frustrated Gd3Ga5O12 Garnet Antiferromagnet.
  Phys. Rev. Lett. 97, 267203 (2006). [Abstract].
• Martin Weigel and Michel J.P. Gingras.
  Ground States and Defect Energies of the Two-dimensional XY Spin Glass from a Quasi-Exact Algorithm.
  Phys. Rev. Lett. 96, 097206 (2006). [Abstract].
• J.-Y.P. Delannoy, M.J.P. Gingras, P. C. W. Holdsworth and A.-M. S. Tremblay.
  Néel Order, Ring Exchange and Charge Fluctuations in the Half-Filled Hubbard Model.
  Phys. Rev. B 72, 115114 (2005). [Abstract].
• Jacob P.C. Ruff, Roger G. Melko and Michel J. P. Gingras.
  Finite Temperature Transitions in Large Magnetic Field in Dipolar Spin Ice.
  Phys. Rev. Lett. 95, 097202 (2005). [Abstract].
• T. Fennell, O.A. Petrenko, B. Fak, S.T. Bramwell, M. Enjalran, T. Yavors'kii, M.J.P. Gingras, R. G. Melko and G. Balakrishnan.
  Neutron Scattering Investigation of the Spin Ice State in Dy2Ti2O7.
  Phys. Rev. B 70, 134408 (2004). [Abstract].
• Adrian G. Del Maestro and Michel J.P. Gingras.
  Quantum Spin Fluctuations in the Dipolar Heisenberg-Like Rare Earth Pyrochlores.
  J. Phys.: Condens. Matter 16, 3339 (2004). [Abstract].
• Roger G. Melko and Michel. J.P. Gingras.
  Monte Carlo Studies of the Dipolar Spin Ice Model.
  J. Phys.: Condens. Matter 16, R1277 (2004). [Abstract].
• M. Enjalran, M.J.P. Gingras, Y.-J. Kao, A. Del Maestro and H.R. Molavian.
  The Spin Liquid State of the Tb2Ti2O7 Pyrochlore Antiferromagnet: A Puzzling State of Affairs.
  J. Phys.: Condens. Matter 16, S673 (2004). [Abstract].
• Matthew Enjalran and Michel J.P. Gingras.
  Theory of paramagnetic scattering in highly frustrated magnets with long-range dipole-dipole interactions: The case of the Tb2Ti2O7, pyrochlore antiferromagnet.
  Phys. Rev. B 70, 174426 (2004). [Abstract].
• Ying-Jer Kao, Matthew Enjalran, Adrian Del Maestro, Hamid R. Molavian and Michel J.P. Gingras.
  Understanding Paramagnetic Spin Correlations in the Spin-Liquid Pyrochlore Tb2Ti2O7.
  Phys. Rev. B 68, 172407 (2003). [Abstract]
• Mohammad Kohandel, Michel J.P. Gingras and Josh P. Kemp.
  Hexatic-Herringbone Coupling at the Hexatic Transition in Smectic Liquid Crystals: 4-ε Renormalization Group Calculations Revisited.
  Phys. Rev. E 68, 041701 (2003). [Abstract]
• H. Fukazawa, R.G. Melko, R. Higashinaka, Y. Maeno, M.J.P. Gingras.
  Magnetic anisotropy of the spin ice compound Dy2Ti2O7.
  Phys. Rev. B 65, 054410 (2002). [Abstract]
• Michel J.P. Gingras and Byron C. den Hertog.
  Origin of Spin Ice Behavior in Ising Pyrochlore Magnets with Long Range Dipole Interactions: an Insight from Mean-Field Theory.
  Can. J. Phys. 79, 1339 (2001). [Abstract].
• Steven T. Bramwell and Michel J.P. Gingras.
  Spin Ice State in Frustrated Magnetic Pyrochlore Materials.
  Science 294, 1495 (2001). [Abstract] | [Full Paper]
• Roger G. Melko, Byron C. den Hertog, and Michel J. P. Gingras.
  Long Range Order at Low Temperature in Dipolar Spin Ice.
  Phys. Rev. Lett. 87, 067203 (2001). Cond-mat/0009225. [Abstract]
• S.T. Bramwell, M.J. Harris, B.C. den Hertog, M.J.P. Gingras, et al.,
  Spin Correlations in Ho₂Ti₂O₇: a Dipolar Spin Ice System.
  Phys. Rev. Lett. 87,047205 (2001). Cond-mat/0101114. [Abstract]
• M. Gingras.
  Spin glass Behavior in Geometrically Frustrated Antiferromagnets.
  To appear in J. of Phys. Cond. Matt, (Review article).
• J.S. Gardner et al.,
  Cooperative Paramagnetism in the Geometrically Frustrated Pyrochlore Antiferromagnet Tb₂Ti₂O₇.
  Phys. Rev. Lett. 82, 1012 (1999).
• E. Sorensen, M. Gingras and D. Huse.
  Non-Trivial Fixed Point Structure of the Two-Dimensional +/-J 3-State Potts Ferromagnet/Spin Glass.
  Euro. phys. Lett 44, 504 (1998). Cond-mat/9801056. [Abstract]
• M.J.P. Gingras, M. Larkin, I. Mirebeau, W.D. Wu, K. Kojima, G.M. Luke, B. Nachumi, and Y.J. Uemura.
  Muon Spin Relaxation Study of Reentrant Spin Glasses: Amorphous-Fe_1-xMn_x.
  Cond-mat/9709190. [Abstract]
• G.M.Luke, Y.Fudamoto, K.M.Kojima, M.Larkin, J.Merrin, B.Nachumi, S.Sinawi, Y.J.Uemura, M.J.P.Gingras, M.Sato, S.Taniguchi, M.Isobe, and Y.Ueda.
  Observation of Spin Freezing in CaV₄O₉ and CaV₂O₅ by muSR.
  Cond-mat/9709123. [Abstract]
• M. Gingras and E. Sorensen.
  Evidence for a Genuine Ferromagnetic to Paramagnetic Reentrant Phase Transition in a Potts Spin Glass Model.
  Phys. Rev. B, 57, 10264 (1998).[Abstract]
• P. Gupta, S. Teitel, and M. Gingras.
  Glassiness vs. Order in Densely Frustrated Josephson Arrays.
  Phys. Rev. Lett. 80, 105 (1998). [Abstract]
• M.J.P. Gingras, C.V. Stager, N.P. Raju, B.D. Gaulin, and J.E. Greedan.
  Static Critical Behavior of the Spin-Freezing Transition in the Geometrically Frustrated Pyrochlore Antiferromagnet Y₂Mo₂O₇.
  Phys. Rev. Lett. 78, 947 (1997).[Abstract]
• G. Ayton, M.J.P. Gingras, G. N. Patey.
  Ferroelectric and Dipolar Glass Phases of Non-Crystalline Systems.
  Phys.Rev. E, 56, 562 (1997).[Abstract]
• S.R. Dunsiger, R.F. Kiefl, K.H. Chow, B.D. Gaulin, M.J.P. Gingras, J.E. Greedan, A. Keren, K. Kojima, G.M. Luke, W.A. MacFarlane, N.P. Raju, J.E. Sonier, Y.J. Uemura, and W.D. Wu.
  MuSR Investigation of the Spin Dynamics of Geometrically Frustrated Antiferromagnets Y₂Mo₂O₇ and Tb₂Mo₂O₇.
  Phys. Rev. B, 54, 9019 (1996). [Abstract]
• M.J.P. Gingras and D.A. Huse.
  Topological Defects in the Random Field XY Model and the Pinned Vortex Lattice to Vortex Glass Transition in Type-II Superconductors.
  Phys. Rev. B 53, 15193 (1996).[Abstract]
• G. Ayton, M.J.P. Gingras and G.N. Patey.
  Orientational Ordering in Spatially Disordered Dipolar Systems.
  Phys. Rev. Lett., 75, 2360 (1995). [Abstract]
• S.T. Bramwell, M.J.P. Gingras and J.N. Reimers. 1994.
  Order by Disorder in an Anisotropic Pyrochlore Lattice Antiferromagnet.
  J. Appl. Phys., 75, 5523 (1994).
• M.J.P. Gingras.
  Ising Spin Glass Order in Vector Spin Glasses with Random Anisotropy.
  Phys. Rev. Lett., 71, 1637 (1993).