McClarty, P. A., Curnoe, S. H., Gingras, M. J. P.
We consider the possibility that the discrete long-range ordered states of Er2Ti2O7 are selected energetically at the mean field level as an alternative scenario that suggests selection via thermal...
Delannoy, J.-Y. P., Gingras, M. J. P., Holdsworth, P. C. W., Tremblay, A.-M. S.
Spin-only descriptions of the half-filled one-band Hubbard model are relevant for a wide range of Mott insulators. In addition to the usual Heisenberg exchange, many new types of interactions,...
Delannoy, J.-Y. P., Gingras, M. J. P., Holdsworth, P. C. W., Tremblay, A.-M. S.
Spin-only descriptions of the half-filled one-band Hubbard model are relevant for a wide range of Mott insulators. In addition to the usual Heisenberg exchange, many new types of interactions,...
Delannoy, J. -Y. P., Gingras, M. J. P., Holdsworth, P. C. W., Tremblay, A. -M. S.
Spin-only descriptions of the half-filled one-band Hubbard model are relevant for a wide range of Mott insulators. In addition to the usual Heisenberg exchange, many new types of interactions,...
Delannoy, J. -Y. P., Del Maestro, A. G., Gingras, M. J. P., Holdsworth, P. C. W.
We study the ground state quantum spin fluctuations around the N\'eel ordered state for the one-band ($t,U$) Hubbard model on a site-diluted square lattice. An effective spin Hamiltonian, $H_{\rm...
Perturbative Quantum Monte Carlo Study of LiHoF4 in a Transverse Magnetic Field (2008)
Tabei, S. M. A, Gingras, M. J. P., Yavors'kii, T.
P.B. Chakraborty {\it et al.}, Phys. Rev. B {\bf 70}, 144411 (2004)) study of the LiHoF$_4$ Ising magnetic material in an external transverse magnetic field $B_x$ show a discrepancy with the...
Tabei, S. M. A., Vernay, F., Gingras, M. J. P.
We present analytical and numerical evidence for the validity of an effective S=1/2 approach to the description of random field generation in S>=1, and especially in an S=1, dipolar spin glass models...
Quilliam, J. A., Ross, K. A., Del Maestro, A. G., Gingras, M. J. P., Corruccini, L. R., Kycia, J. B.
We have measured the low-temperature specific heat of the geometrically frustrated pyrochlore Heisenberg antiferromagnet Gd2Sn2O7 in zero magnetic field. The specific heat is found to drop...
Momentum dependent light scattering in insulating cuprates (2007)
Vernay, F. H., Gingras, M. J. P., Devereaux, T. P.
We investigate the problem of inelastic x-ray scattering in the spin$-{1/2}$ Heisenberg model on the square lattice. We first derive a momentum dependent scattering operator for the $A_{1g}$ and...
Tabei, S. M. A., Gingras, M. J. P., Stasiak, P.
The LiHo$_x$Y$_{1-x}$F$_4$ magnetic material in a transverse magnetic field $B_{x}\hat x$ perpendicular to the Ising spin direction has long been used to study tunable quantum phase transitions in a...
Raman scattering for triangular lattices spin-1/2 Heisenberg antiferromagnets (2006)
Vernay, F., Devereaux, T. P., Gingras, M. J. P.
Motivated by various spin-1/2 compounds like Cs$_2$CuCl$_4$ or $\kappa$-(BEDT-TTF)$_2$Cu$_2$(CN)$_3$, we derive a Raman-scattering operator {\it \`a la} Shastry and Shraiman for various geometries....
Neel order, ring exchange and charge fluctuations in the half-filled Hubbard model (2004)
Delannoy, J. -Y. P., Gingras, M. J. P., Holdsworth, P. C. W., Tremblay, A. -M. S.
We investigate the ground state properties of the two dimensional half-filled one band Hubbard model in the strong (large-U) to intermediate coupling limit ({\it i.e.} away from the strict Heisenberg...
Neutron Scattering Investigation of the Spin Ice State in Dy2Ti2O7 (2004)
Fennell, T., Petrenko, O. A., Fak, B., Bramwell, S. T., Enjalran, M., Yavors'kii, T., ...
Dy2Ti2O7 has been advanced as an ideal spin ice. We present a neutron scattering investigation of a sample of 162Dy2Ti2O7. The scattering intensity has been mapped in zero applied field in the hhl...
Neutron scattering investigation of the spin ice state in Dy2Ti2O7 (2004)
Fennell, T, Petrenko, O A, Fak, B, Bramwell, S T, Enjalran, M, Yavors'kii, T, ...
Dy2Ti2O7 has been advanced as an ideal spin ice material. We present a neutron scattering investigation of a single-crystal sample of (Dy2Ti2O7)-Dy-162. The scattering intensity has been mapped in...
The Spin Liquid State of the Tb2Ti2O7 Pyrochlore Antiferromagnet: A Puzzling State of Affairs (2003)
Enjalran, M., Gingras, M. J. P., Del Maestro, A., Molavian, H. R.
The pyrochlore antiferromagnet Tb2Ti2O7 has proven to be an enigma to experimentalists and theorists working on frustrated magnetic systems. The experimentally determined energy level structure...
Pressure-induced crystallization of a spin liquid (2002)
Mirebeau, I., Goncharenko, I.N., Cadavez-Peres, P., Bramwell, S.T., Gingras, M.J.P., Gardner, J.S.
Liquids are expected to crystallize at low temperature. The only exception is helium, which can remain liquid at 0 K, owing to quantum fluctuations1, 2. Similarly, the atomic magnetic moments (spins)...
Spin ice state in frustrated magnetic pyrochlore materials (2001)
Bramwell, S.T., Gingras, M.J.P.
A frustrated system is one whose symmetry precludes the possibility that every pairwise interaction ("bond") in the system can be satisfied at the same time. Such systems are common in all areas of...
Magnetic anisotropy of the spin ice compound Dy2Ti2O7 (2001)
Fukazawa, H., Melko, R. G., Higashinaka, R., Maeno, Y., Gingras, M. J. P.
We report magnetization and ac susceptibility of single crystals of the spin ice compound Dy2Ti2O7. Saturated moments at 1.8 K along the charasteristic axes [100] and [110] agree with the expected...
Spin Correlations in Ho$_{2}$Ti$_{2}$O$_{7}$: a Dipolar Spin Ice System (2001)
Bramwell, S. T., Harris, M. J., Hertog, B. C. Den, Gingras, M. J. P., Gardner, J. S., McMorrow, D. F., ...
The pyrochlore material $\rm Ho_{2}Ti_{2}O_{7}$ has been suggested to show ``spin ice'' behaviour. We present neutron scattering and specific heat results that establish unambiguously that...
Spin correlations in Ho2Ti2O7: A dipolar spin ice system (2001)
Bramwell, S T, Harris, M J, Den Hertog, B C, Gingras, M J P, Gardner, J S, McMorrow, D F, ...
Frustrated Order by Disorder: the Pyrochlore Antiferromagnet with Bond Disorder (2000)
Bellier-Castella, L., Gingras, M. J. P., Holdsworth, P. C. W., Moessner, R.
The classical Heisenberg antiferromagnet on the pyrochlore lattice is macroscopically and continuously degenerate and the system remains disordered at all temperatures, even in the presence of weak...
Gingras, M. J. P., Hertog, B. C. Den, Faucher, M., Gardner, J. S., Chang, L. J., Gaulin, B. D., ...
In a recent letter [Phys. Rev. Lett. {\bf 82}, 1012 (1999)] it was found that the Tb$^{3+}$ magnetic moments in the Tb$_2$Ti$_2$O$_7$ pyrochlore lattice of corner-sharing tetrahedra remain in a {\it...
Raju, N. P., Dion, M., Gingras, M. J. P., Mason, T. E., Greedan, J. E.
Experimental evidence from measurements of the a.c. and d.c. susceptibility, and heat capacity data show that the pyrochlore structure oxide, Gd_2Ti_2O_7, exhibits short range order that starts...
Gingras, M. J. P., Sorensen, Erik S.
uch experimental and theoretical efforts have been devoted in the past twenty years to search for a genuine thermodynamic reentrant phase transition from a ferromagnetic to either a paramagnetic or...
Muon Spin Relaxation Study of Reentrant Spin Glasses: Amorphous-Fe_{1-x}Mn_x (1997)
Gingras, M. J. P., Larkin, M., Mirebeau, I., Wu, W. D., Kojima, K., Luke, G. M., ...
We have performed an extensive muon spin relaxation study of the well known (Fe$_{1-x}$Mn$_{x}$)$_{75}$P$_{16}$B$_6$Al$_3$ reentrant spin glass. We find a strong increase of the dynamic as well as...
Observation of Spin Freezing in CaV4O9 and CaV2O5 by uSR (1997)
Luke, G. M., Fudamoto, Y., Kojima, K. M., Larkin, M., Merrin, J., Nachumi, B., ...
We have performed muon spin relaxation and susceptibility measurements of CaV_4O_9 and CaV_2O_5, systems in which spin gap-like behavior has been found. We observe spin freezing in the two compounds...
Ferroelectric and Dipolar Glass Phases of Non-Crystalline Systems (1997)
Ayton, G., Gingras, M. J. P., Patey, G. N.
In a recent letter [Phys. Rev. Lett. {\bf 75}, 2360 (1996)] we briefly discussed the existence and nature of ferroelectric order in positionally disordered dipolar materials. Here we report further...
Dunsiger, S. R., Kiefl, R. F., Chow, K. H., Gaulin, B. D., Gingras, M. J. P., Greedan, J. E., ...
The spin dynamics of geometrically frustrated pyrochlore antiferromagnets Y2Mo2O7 and Tb2Mo2O7 have been investigated using muon spin relaxation. A dramatic slowing down of the moment fluctuations...
Gingras, M. J. P., Stager, C. V., Raju, N. P., Gaulin, B. D., Greedan, J. E.
Some frustrated pyrochlore antiferromagnets, such as Y2Mo2O7, show a spin-freezing transition and magnetic irreversibilities below a temperature Tf similar to what is observed nonlinear magnetization...
Orientational Ordering in Spatially Disordered Dipolar Systems (1995)
Ayton, G., Gingras, M. J. P., Patey, G. N.
This letter addresses basic questions concerning ferroelectric order in positionally disordered dipolar materials. Three models distinguished by dipole vectors which have one, two or three components...