Quantum magnets under pressure: controlling elementary excitations in TlCuCl₃ (2008)
Rüegg, Ch., Normand, Bruce, Matsumoto, M., Furrer, A., McMorrow, D. F., Krämer, K. W., ...
We follow the evolution of the elementary excitations of the quantum antiferromagnet TlCuCl₃ through the pressure-induced quantum critical point, which separates a dimer-based quantum disordered...
Forrest, T. R., Bland, S. R., Wilkins, S. B., Walker, H. C., Beale, T. A. W., Hatton, P. D., ...
Soft X-ray resonant scattering (XRS) has been used to observe directly, for the first time, the ordering of localized electronic states on both the Mn and Tb sites in multiferroic TbMnO$_3$. Large...
Quantum magnets under pressure: controlling elementary excitations in TlCuCl₃ (2008)
Rüegg, Ch., Normand, Bruce, Matsumoto, M., Furrer, A., McMorrow, D. F., Krämer, K. W., ...
We follow the evolution of the elementary excitations of the quantum antiferromagnet TlCuCl₃ through the pressure-induced quantum critical point, which separates a dimer-based quantum disordered...
Thielemann, B., Rüegg, Ch., Kiefer, K., Rønnow, H. M., Bouillot, P., Kollath, C., ...
The transition from a magnetic field-tuned spin Luttinger-liquid with algebraic spin correlations to a Bose-Einstein Condensate of magnons with long-range magnetic order is investigated in the...
Thermodynamics of the Spin Luttinger-Liquid in a Model Ladder Material (2008)
Rüegg, Ch., Kiefer, K., Thielemann, B., McMorrow, D. F., Zapf, V., Normand, B., ...
The phase diagram in temperature and magnetic field of the metal-organic, two-leg, spin-ladder compound (C5H12N)2CuBr4 is studied by measurements of the specific heat and the magnetocaloric effect....
Chang, J., Niedermayer, Ch., Gilardi, R., Christensen, N. B., Ronnow, H. M., McMorrow, D. F., ...
We report the results of a combined muon spin rotation and neutron scattering study on La2-xSrxCuO4 in the vicinity of the so-called 1/8-anomaly. Application of a magnetic field drives the system...
An x-ray resonant diffraction study of multiferroic DyMn2O5 (2007)
Ewings, R. A., Boothroyd, A. T., McMorrow, D. F., Mannix, D., Walker, H. C., Wanklyn, B. M. R.
X-ray resonant scattering has been used to measure the magnetic order of the Dy ions below 40K in multiferroic DyMn$_{2}$O$_{5}$. The magnetic order has a complex behaviour. There are several...
X-ray Resonant Scattering Study of the Order Parameters in Multiferroic TbMnO$_3$ (2007)
Mannix, D., McMorrow, D. F., Ewings, R. A., Boothroyd, A. T., Prabhakaran, D., Joly, Y., ...
We report on an extensive investigation of the multiferroic compound TbMnO$_3$. Non-resonant x-ray magnetic scattering (NRXMS) revealed a dominant $A$-type domain. The temperature dependence of the...
Webster, C. H., Helme, L. M., Boothroyd, A. T., McMorrow, D. F., Wilkins, S. B., Detlefs, C., ...
A synchrotron x-ray diffraction study of the crystallographic structure of PrO2 in the Jahn-Teller distorted phase is reported. The distortion of the oxygen sublattice, which was previously...
Quantum dynamics and entanglement of spins on a square lattice (2007)
Christensen, N. B., Ronnow, H. M., McMorrow, D. F., Harrison, A., Perring, T. G., Enderle, M., ...
Bulk magnetism in solids is fundamentally quantum mechanical in nature. Yet in many situations, including our everyday encounters with magnetic materials, quantum effects are masked, and it often...
Inelastic X-ray Scattering Study of Phonons in Superconducting CaC6 (2007)
Upton, M. H., Walters, A. C., Howard, C. A., Rahnejat, K. C., Ellerby, M., Hill, J. P., ...
We investigate the dispersion and temperature dependence of a number of phonons in the recently discovered superconductor CaC6 utilizing inelastic x-ray scattering. Four [00L] and two ab-plane phonon...
Pinch Points and Kasteleyn Transitions: How Spin Ice Changes its Entropy (2007)
Fennell, T., Bramwell, S. T., McMorrow, D. F., Manuel, P.
Complex disordered states - from liquids and glasses to exotic quantum matter - are ubiquitous in nature. Their key properties include finite entropy, power-law correlations and emergent organising...
Pinch points and Kasteleyn transitions in kagome ice (2007)
Fennell, T., Bramwell, S.T., McMorrow, D.F., Manuel, P., Wildes, A.R.
Complex disordered states—from liquids and glasses to exotic quantum matter—are ubiquitous in nature. Their key properties include finite entropy, power-law correlations and emergent organizing...
Lipscombe, O. J., Hayden, S. M., Vignolle, B., McMorrow, D. F., Perring, T. G.
We report a detailed inelastic neutron scattering study of the collective magnetic excitations of overdoped superconducting La1.78Sr0.22CuO4 for the energy range 0-160 meV. Our measurements show that...
Understanding the quadrupolar structures of UPd3UPd3 (2007)
McEwen, K.A., Walker, H.C., Le, M.D., McMorrow, D.F., Colineau, E., Wastin, F., ...
UPd3 exhibits four phase transitions below T0 = 7.8 K, attributed to a succession of antiferroquadrupolar (AFQ) orderings of the 5f2 uranium ions localised on the quasi-cubic sites of the dhcp...
Ronnow, H. M., McMorrow, D. F., Harrison, A.
The temperature dependence of the structure factor S(k) of the instantaneous magnetic fluctuations in copper formate tetradeuterate has been investigated using neutron scattering techniques. Our data...
Neutron scattering study of the incommensurate high-field phase of CuGeO3 (2007)
Ronnow, H. M., Enderle, M., McMorrow, D. F., Regnault, L. P., Dhalenne, G., Revcolevschi, A., ...
CuGeO3 is a good realization of a spin-Peierls system. Using neutron scattering, we have investigated the transition from the dimerized spin-Peierls phase to an incommensurately modulated high-field...
Neutron scattering study of the field-induced soliton lattice in CuGeO3 (2007)
Ronnow, H. M., Enderle, M., McMorrow, D. F., Regnault, L. P., Dhalenne, G., Revcolevschi, A., ...
CuGeO3 undergoes a transition from a spin-Peierls phase to an incommensurate phase at a critical field of H-c approximate to 12.5 T. In the high-field phase a lattice of solitons forms, with both...
Added flexibility in triple axis spectrometers: the two RITAs at Riso (2007)
Lefmann, K., McMorrow, D. F., Ronnow, H. M., Nielsen, K., Clausen, K. N., Lake, B., ...
The cold-neutron triple-axis spectrometer RITA-I at Rise has been operational for about three years, and in the near future an improved version, RITA-2 will replace the existing triple-axis...
Correlations and fluctuations in the 2D Heisenberg antiferromagnet (2007)
Ronnow, H. M., McMorrow, D. F., Harrison, A., Youngson, I. D., Coldea, R., Perring, T. G., ...
The correlations and fluctuations in Cu(DCOO)(2). 4D(2)O, which is a good physical realization of the 2D S = 1/2 Heisenberg antiferromagnet on a square lattice, have been measured by neutron...
Ronnow, H. M., McMorrow, D. F., Coldea, R., Harrison, A., Youngson, I. D., Perring, T. G., ...
The magnetic excitation spectrum in the two-dimensional (2D) S = 1/2 Heisenberg antiferromagnet copper deuteroformate tetradeuterate has been measured for temperatures up to T similar to J/2, where J...
X-ray resonant scattering study of the quadrupolar order in UPd3 (2007)
McMorrow, D. F., McEwen, K. A., Steigenberger, U., Ronnow, H. M., Yakhou, F.
Quadrupolar ordering in a 5f electron system has been observed directly for the first time, using x-ray scattering techniques. In UPd3 at low temperatures satellite peaks appear at (1, 0, l)...
Statics and dynamics of the magnetic soliton lattice in the high-field phase of CuGeO3 (2007)
Enderle, M., Ronnow, H. M., McMorrow, D. F., Regnault, L. P., Vorderwisch, P., Meissner, M., ...
Driven by antiferromagnetic quantum fluctuations on a deformable lattice, spin-Peierls systems dimerize magnetically and structurally at low temperatures. In this dimer phase all excitations with...
Excitations of the field-induced quantum soliton lattice in CuGeO3 (2007)
Enderle, M., Ronnow, H. M., McMorrow, D. F., Regnault, L. P., Dhalenne, G., Revcholevschi, A., ...
The incommensurate magnetic soliton lattice in the high-field phase of a spin-Peierls system results from quantum fluctuations. We have used neutron scattering techniques to study CuGeO3, allowing us...
Lake, B., Ronnow, H. M., Christensen, N. B., Aeppli, G., Lefmann, K., McMorrow, D. F., ...
One view of the high-transition-temperature (high-T-c) copper oxide superconductors is that they are conventional superconductors where the pairing occurs between weakly interacting quasi-particles...
Field-induced antiferromagnetism in the high-temperature superconductor La2-xSrxCuO4 (2007)
Lake, B., Mason, T. E., Aeppli, G., Lefmann, K., Christensen, N. B., McMorrow, D. F., ...
Vortex magnetism in the high-temperatures superconductor La2-xSrxCuO4 (2007)
Lake, B., Mason, T. E., Aeppli, G., Lefmann, K., Christensen, N. B., McMorrow, D. F., ...
The field-induced soliton phase of CuGeO3 (2007)
Ronnow, H. M., Mechthild, E., McMorrow, D. F., Regnault, L. P.
The quasi-1D S = 1/2 antiferromagnet CuGeO3 undergoes a spin-Peierls transition to a dimerised singlet quantum ground state, with S = 1 carrying pairs of domain walls as elementary excitations....
Static and dynamic spins in superconducting La2-xSrxCuO4: The Riso years (2007)
Lefmann, K., Lake, B., Aeppli, G., Cheong, S. W., Christensen, N. B., Clausen, K. N., ...
One important area of modern condensed matter research is the investigation of the nature of the superconducting cuprates. Much progress in this field has been obtained with the technique of neutron...
Effects of magnetic field on the cuprate high-T-c superconductor La2-xSrxCuO4 (2007)
Lake, B., Aeppli, G., Christensen, N. B., Lefmann, K., McMorrow, D. F., Clausen, K. N., ...
This article discusses neutron scattering measurements on the cuprate, high transition temperature superconductor La2-xSrxCuO4 (LSCO) in an applied magnetic field. LSCO is a type-II superconductor...
Dispersive excitations in the high-temperature superconductor La2-xSrxCuO4 (2007)
Christensen, N. B., McMorrow, D. F., Ronnow, H. M., Lake, B., Hayden, S. M., Aeppli, G., ...
High-resolution neutron scattering experiments on optimally doped La2-xSrxCuO4 (x=0.16) reveal that the magnetic excitations are dispersive. The dispersion is the same as in YBa2Cu3O6.85, and is...
Deviations from linear spin wave theory in the 2D, S=1/2 Heisenberg antiferromagnet CFTD (2007)
Christensen, N. B., McMorrow, D. F., Ronnow, H. M., Harrison, A., Perring, T. G., Coldea, R.
The spin excitation spectrum in the 2D square lattice Heisenberg antiferromagnet CFTD has been investigated using time-of-flight neutron scattering. The magnon dispersion and intensities have been...
Quantum phase transition of a magnet in a spin bath (2007)
Ronnow, H. M., Parthasarathy, R., Jensen, J., Aeppli, G., Rosenbaum, T. F., McMorrow, D. F.
The excitation spectrum of a model magnetic system, LiHoF4, was studied with the use of neutron spectroscopy as the system was tuned to its quantum critical point by an applied magnetic field. The...
Three-dimensionality of field-induced magnetism in a high-temperature superconductor (2007)
Lake, B., Lefmann, K., Christensen, N. B., Aeppli, G., McMorrow, D. F., Ronnow, H. M., ...
Many physical properties of high-temperature superconductors are two-dimensional phenomena derived from their square-planar CuO2 building blocks. This is especially true of the magnetism from the...
Chang, J., Schnyder, A. P., Gilardi, R., Ronnow, H. M., Pailhes, S., Christensen, N. B., ...
High-resolution neutron inelastic scattering experiments in applied magnetic fields have been performed on La$_{1.895}$Sr$_{0.105}$CuO$_{4}$ (LSCO). In zero field, the temperature dependence of the...
Vignolle, B., Hayden, S. M., McMorrow, D. F., Ronnow, H. M., Lake, B., Frost, C. D., ...
The excitations responsible for producing high-temperature superconductivity in the cuprates have not been identified. Two promising candidates are collective spin excitations and phonons. A recent...
Determination of the Antiferroquadrupolar Order Parameters in UPd3 (2006)
Walker, H. C., McEwen, K. A., McMorrow, D. F., Wilkins, S. B., Wastin, F., Colineau, E., ...
By combining accurate heat capacity and X-ray resonant scattering results we have resolved the long standing question regarding the nature of the quadrupolar ordered phases in UPd_3. The order...
Magnetic Excitation Spectrum of the Square Lattice S=1/2 Heisenberg Antiferromagnet K2V3O8 (2006)
Lumsden, M. D., Nagler, S. E., Sales, B. C., Tennant, D. A., McMorrow, D. F., ...
We have explored the magnetic excitation spectrum of the S=1/2 square lattice Heisenberg antiferromagnet, K2V3O8 using both triple-axis and time-of-flight inelastic neutron scattering. The...
Determination of the antiferroquadrupolar order parameters in UPd3 (2006)
Walker, H.C., McEwen, K.A., McMorrow, D.F., Wilkins, S.B., Wastin, F., Colineau, E., ...
By combining accurate heat capacity and x-ray resonant scattering results we have resolved the long standing question regarding the nature of the quadrupolar ordered phases in UPd3. The order...
Christensen, N. B., Ronnow, H. M., Mesot, J., Ewings, R. A., Momono, N., Oda, M., ...
Using polarized neutron scattering we establish that the magnetic order in La$_{1.48}$Nd$_{0.4}$Sr$_{0.12}$CuO$_4$ is either (i) one dimensionally modulated and collinear, consistent with the stripe...
Multiple Magnon Modes and Consequences for the Bose-Einstein Condensed Phase in BaCuSi2O6 (2006)
Rüegg, Ch., McMorrow, D. F., Normand, B., Ronnow, H. M., Sebastian, S. E., Fisher, I. R., ...
The compound BaCuSi2O6 is a quantum magnet with antiferromagnetic dimers of S = 1/2 moments on a quasi-2D square lattice. We have investigated its spin dynamics by inelastic neutron scattering...
Three-dimensionality of field-induced magnetism in a high-temperature superconductor (2006)
Lake, B., Lefmann, K., Christensen, N. B., Aeppli, G., McMorrow, D. F., Ronnow, H. M., ...
Many physical properties of high-temperature (high-Tc) superconductors are two-dimensional phenomena derived from their square planar CuO2 building blocks. This is especially true of the magnetism...
Quantum Phase Transition of a Magnet in a Spin Bath (2005)
Ronnow, H. M., Parthasarathy, R., Jensen, J., Aeppli, G., Rosenbaum, T. F., McMorrow, D. F.
The excitation spectrum of a model magnetic system, LiHoF$_4$, has been studied using neutron spectroscopy as the system is tuned to its quantum critical point by an applied magnetic field. The...
Magnetic excitations in {Mo72Fe30} (2005)
Garlea, V. O., Nagler, S. E., Zarestky, J. L., Stassis, C., Vaknin, D., Kogerler, P., ...
We report cold-neutron inelastic neutron scattering measurements on deuterated samples of the giant polyoxomolybdate magnetic molecule {Mo72Fe30}. The 30 s = 5/2 Fe+3 ions occupy the vertices of an...
Inelastic neutron scattering study of single crystal heavy fermion YbAgGe (2004)
Fak, B., McMorrow, D. F., Niklowitz, P. G., Raymond, S., Ressouche, E., Flouquet, J., ...
Single crystals of the heavy-fermion compound YbAgGe have been studied by neutron scattering. The magnetic ordering occurring below T1=0.5 K is characterized by a commensurate propagation vector...
Dispersive Excitations in the High-Temperature Superconductor La2-xSrxCuO4 (2004)
Christensen, N.B., McMorrow, D.F., Ronnow, H.M., Lake, B., Hayden, S.M., Aeppli, G., ...
High-resolution neutron scattering experiments on optimally doped La2-xSrxCuO4 (x=0.16) reveal that the magnetic excitations are dispersive. The dispersion is the same as in YBa2Cu3O6.85, and is...
Universal Dispersive Excitations in the High-Temperature Superconductors (2004)
Christensen, N. B., McMorrow, D. F., Ronnow, H. M., Lake, B., Hayden, S. M., Aeppli, G., ...
High-resolution neutron scattering experiments on optimally doped La$_{2-x}$Sr$_x$CuO$_4$ have been performed which reveal that the magnetic excitations are dispersive. The dispersion is found to be...
Dispersive excitations in the high-temperature superconductor La2-xSrxCuO4 (2004)
Christensen, N B, McMorrow, D F, Ronnow, H M, Lake, B, Hayden, S M, Aeppli, G, ...
Deviations from linear spin wave theory in the 2D, S=1/2 Heisenberg antiferromagnet CFTD (2004)
Christensen, N B, McMorrow, D F, Ronnow, H M, Harrison, A, Perring, T G, Coldea, R
Static and dynamic spins in superconducting La2-xSrxCuO4: The Riso years (2004)
Lefmann, K, Lake, B, Aeppli, G, Cheong, S W, Christensen, N B, Clausen, K N, ...
Coupling of lattice and spin degrees of freedom in GdB6 (2004)
McMorrow, D F, McEwen, K A, Park, J G, Lee, S, Mannix, D, Iga, F, ...
Thomas, K J, Hill, J P, Grenier, S, Kim, Y J, Abbamonte, P, Venema, L, ...
Thomas, K. J., Hill, J. P., Kim, Y-J., Grenier, S., Abbamonte, P., Venema, L., ...
We have utilized the resonant x-ray diffraction technique at the Mn L-edge in order to directly compare magnetic and orbital correlations in the Mn sub-lattice of Pr0.6Ca0.4MnO3. The resonant line...
Lake, B., Rønnow, H.M., Christensen, N.B., Aeppli, G., Lefmann, K., McMorrow, D.F., ...
One view of the high-transition-temperature (high-Tc) copper oxide superconductors is that they are conventional superconductors where the pairing occurs between weakly interacting quasiparticles...
Quantum critical fluctuations in heavy fermion compounds (2002)
Schroeder, A., Aeppli, G., Coleman, P., Ramazashvili, R., Coldea, R., Adams, M., ...
The electronic properties of heavy fermion alloys are dominated by spin fluctuations which are expected to become critical when tuned by pressure to a quantum critical point (QCP), entering a...
Kenzelmann, M., Cowley, R. A., Buyers, W. J. L., Coldea, R., Enderle, M., McMorrow, D. F.
We have mapped from the quantum to the classical limit the spin excitation spectrum of the antiferromagnetic spin-1 Heisenberg chain system CsNiCl3 in its paramagnetic phase from T=5 to 200K. Neutron...
Er2Ti2O7: Evidence of Order by Disorder in a Frustrated Antiferromagnet (2001)
Champion, J. D. M., Harris, M. J., Holdsworth, P. C. W., Wills, A. S., Balakrishnan, G., Bramwell, S. T., ...
Er_2Ti_2O_7 has been suggested to be a realization of the frustrated < 111 > XY pyrochlore lattice antiferromagnet, for which theory predicts fluctuation-induced symmetry breaking in a highly...
Ronnow, H.M., McMorrow, D.F., Coldea, R., Harrison, A., Youngson, I.D., Perring, T.G., ...
The magnetic excitation spectrum in the two-dimensional (2D) S = 1/2 Heisenberg antiferromagnet copper deuteroformate tetradeuterate has been measured for temperatures up to T∼J/2, where J =...