Search

Your search keyword '"Lorenzo, J. E."' showing total 233 results
Start Over Author "Lorenzo, J. E."
233 results on '"Lorenzo, J. E."'

110. Thermal contraction at the spin-Peierls transition inCuGeO3

Author

Harris, Q. J., primary, Feng, Q., additional, Birgeneau, R. J., additional, Hirota, K., additional, Kakurai, K., additional, Lorenzo, J. E., additional, Shirane, G., additional, Hase, M., additional, Uchinokura, K., additional, Kojima, H., additional, Tanaka, I., additional, and Shibuya, Y., additional

Published
1994
Full Text
View/download PDF

113. Dimerization ofCuGeO3in the Spin-Peierls State

Author

Hirota, K., primary, Cox, D. E., additional, Lorenzo, J. E., additional, Shirane, G., additional, Tranquada, J. M., additional, Hase, M., additional, Uchinokura, K., additional, Kojima, H., additional, Shibuya, Y., additional, and Tanaka, I., additional

Published
1994
Full Text
View/download PDF

114. Soft longitudinal modes in spin-singletCuGeO3

Author

Lorenzo, J. E., primary, Hirota, K., additional, Shirane, G., additional, Tranquada, J. M., additional, Hase, M., additional, Uchinokura, K., additional, Kojima, H., additional, Tanaka, I., additional, and Shibuya, Y., additional

Published
1994
Full Text
View/download PDF

118. Magnetic chirality of the spin triplet in the spin-ladder compound Sr14Cu24O41 as seen via polarized inelastic neutron scattering.

Author

Lorenzo, J. E., Regnault, L. P., Boullier, C., Martin, N., Vanishri, S., and Mann, C.

Subjects
*CHIRALITY, *MAGNETISM, *MAGNETS, *NEUTRONS, *MAGNETIC fields
Abstract

We report the direct observation by polarized inelastic neutron scattering experiments at low fields (3.5 T) of the splitting of the spin triplet of magnetic excitations in the response associated with the ladders in the composite cuprate Sr14Cu24O41. By conveniently choosing the magnetic field configuration and by making use of the spin chirality of the excitations, the splitting can be observed at relatively low fields. In this way, resonant excitations can be separated from the remainder of magnetic and phonon excitations at high temperatures. In Sr14Cu24O41, the 32-meV gapped mode vanishes above ∼200 K, close to the hole-crystal melting temperature previously observed by resonant x-ray and neutron diffraction. [ABSTRACT FROM AUTHOR]

Published
2011
Full Text
View/download PDF

129. Statistical theory of α-alanine doped triglycine sulphate near Tc and comparison with experimental data

Author

Lorenzo, J. E., Martinez, J. L., and Gonzalo, J. A.

Abstract

The ferroelectric behaviour of α-alanine doped triglycine sulphate crystals is characterized by the presence of an effective internal bias which shows a pronounced temperature dependence near Tc. Samples with three different concentrations of α-alanine have been investigated by means of hysteresis loops and dielectric constant measurements. It is shown that a simple statistical theory, which takes duly into account the distinct response of polar centers associated with molecular units (containing α-alanine) and normal molecular units (containing only glycine), describes consistently the observed temperature and concentration dependence of the internal bias.

Published
1988
Full Text
View/download PDF

131. Chasing ghosts in reciprocal space - a novel inelastic neutron multiple scattering process

Author

Ronnow, H. M., Regnault, L. P., and Lorenzo, J. E.

Subjects
neutron, copper germanate CuGeO3, Condensed Matter::Strongly Correlated Electrons, PEIERLS COMPOUND CUGEO3, inelastic neutron scattering, polarisation analysis
Abstract

We have discovered that a recently reported weak excitation branch in the spin-Peierls material CuGeO3 is in fact a ghost image of the primary magnetic excitation shifted in reciprocal space by a novel multiple scattering process. A model is developed that predicts the occurrence of such multiple scattering and accounts for the observations in CuGeO3. New 'ghostons' can occur when the magnetic unit cell is smaller than the structural, while mixing of intensities from different reciprocal space zones jeopardize accurate polarisation analysis and the study of weak modes in general. (C) 2004 Elsevier B.V. All rights reserved.

138. Increase of the charge density wave phase coherence in the sliding and the mode-locked state

Author

Danneau, R., Ayari, A., Rideau, D., Requardt, H., Lorenzo, J. E., Ortega, L., Monceau, P., Currat, R., Grübel, G., Danneau, R., Ayari, A., Rideau, D., Requardt, H., Lorenzo, J. E., Ortega, L., Monceau, P., Currat, R., and Grübel, G.

Abstract

Using high-resolution x-ray techniques coupled to in situ electrical measurements, we have measured the spatial coherence of the charge density waves (CDW) in the sliding state without and with a rf field. In the first case, at T = 100 K , we find that the CDW becomes more ordered in the direction of the motion, while the transverse correlation is reduced. With the application of a rf field in the mode locked state, we find that the longitudinal correlation length is even larger.

Published
2002
Full Text
View/download PDF

148. Static and dynamic properties of low-temperature order in the one-dimensional semiconductor (NbSe4)3I.

Author

Dominko, D., Vdović, S., Skenderović, H., Starešinić, D., Biljaković, K., Ristić, D., Ivanda, M., Lorenzo, J. E., and Demsar, J.

Subjects
*ONE-dimensional conductors, *PUMP probe spectroscopy, *JAHN-Teller transitions, *POLARIZATION (Electricity), *ANTIFERROELECTRIC materials, *ORDER-disorder transitions
Abstract

We investigated static and dynamic lattice properties in a quasi-one-dimensional charge-ordered semiconductor (NbSe4)3I by using Raman, femtosecond pump-probe spectroscopy and x-ray diffraction. In addition to a well-documented pseudo-Jahn-Teller ferrodistortive structural transition at TC=274 K, where the displacements of Nb ions lead to ferroelectric (FE) in-chain polarization with opposite direction in adjacent chains, all methods suggest an additional lowering of symmetry at T*≈160 K. Although antiferroelectric (AFE) phase is partially formed at TC, our results consistently point to an enhancement of the interchain order at T*, thus leading to AFE order-disorder transition, as supported by the earlier dielectric and structural studies. [ABSTRACT FROM AUTHOR]

Published
2016
Full Text
View/download PDF

149. Macroscopic quantum coherence of the spin triplet in the spin-ladder compound Sr14Cu24O41.

Author

Lorenzo JE, Regnault LP, Boullier C, Martin N, Moudden AH, Vanishri S, Marin C, and Revcolevschi A

Abstract

We report the direct observation by inelastic neutron scattering experiments of a spin triplet of magnetic excitations in the response associated with the ladders in the composite cuprate Sr14Cu24O41. This appears as a peak at q(Q1D)=π and energy Δ1=32.5  meV, and we conjecture that all the triplets making up this conspicuous peak have the same phase and therefore interpret it as the signature of the occurrence of quantum coherence along the ladder direction between entangled spin pairs. From the comparison with previous neutron and x-ray data, we conclude that the temperature evolution of this mode is driven by the crystallization of holes into a charge density wave in the ladder sublattice.

Published
2010
Full Text
View/download PDF

150. Sliding-induced decoupling and charge transfer between the coexisting Q1 and Q2 charge density waves in NbSe3.

Author

Ayari A, Danneau R, Requardt H, Ortega L, Lorenzo JE, Monceau P, Currat R, Brazovskii S, and Grübel G

Abstract

Using high-resolution x-ray scattering in the presence of an applied current, we report evidence for a dynamical decoupling between the two NbSe3 charge-density waves (CDWs), Q1 (T(C1)=145 K) and Q2 (T(C2)=59 K), coexisting below T(C2). Simultaneous and oppositely directed shifts of the relevant CDW superlattice spots develop above a threshold current which we identify as the depinning threshold I(C1) for the more strongly pinned upper CDW Q1 (I(C1) approximately 10I(C2)). In contrast with shifts induced by current conversion processes, the present effect is not current polarized and is not limited to the current-contact regions. We propose a model which explains this instability through a sliding-induced charge transfer between the two electronic reservoirs corresponding to the Q1 and Q2 CDWs.

Published
2004
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results