D. McK. Paul
University of Warwick
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Featured researches published by D. McK. Paul.
Physical Review B | 2004
V. Hardy; S. Majumdar; S. J. Crowe; Martin R. Lees; D. McK. Paul; L. Hervé; A. Maignan; S. Hébert; Clough John Martin; C. Yaicle; M. Hervieu; B. Raveau
Field-induced magnetization jumps with similar characteristics are observed at low temperature for the intermetallic germanide
Physical Review B | 2013
Ning Xu; X. Shi; P. K. Biswas; Chiang Matt; R. S. Dhaka; Yuh-Chin T. Huang; N. C. Plumb; M. Radovic; J. H. Dil; E. Pomjakushina; K. Conder; A. Amato; Zaher Salman; D. McK. Paul; J. Mesot; H. Ding; M. Shi
{\mathrm{Gd}}_{5}{\mathrm{Ge}}_{4}
Physical Review B | 2003
V. Hardy; S. Lambert; Martin R. Lees; D. McK. Paul
and the mixed-valent manganite
Physica C-superconductivity and Its Applications | 1990
S. Piñol; J. Fontcuberta; C. Miravitlles; D. McK. Paul
{\mathrm{Pr}}_{0.6}{\mathrm{Ca}}_{0.4}{\mathrm{Mn}}_{0.96}{\mathrm{Ga}}_{0.04}{\mathrm{O}}_{3}.
Solid State Communications | 1990
E.T. Heyen; G. Kliche; W. Kress; W. König; M. Cardona; E. Rampf; J. Prade; U. Schröder; Anil D. Kulkarni; F. W. de Wette; S. Piñol; D. McK. Paul; E. Morán; M.A. Alario-Franco
We report that the field location\char22{}and even the existence\char22{}of these jumps depends critically on the magnetic field sweep rate used to record the data. It is proposed that, for both compounds, the martensitic character of their antiferromagnetic-to-ferromagnetic transitions is at the origin of the magnetization steps.
Applied Physics Letters | 1996
J. Barratt; Martin R. Lees; Geetha Balakrishnan; D. McK. Paul
Recent theoretical calculations and experimental results suggest that the strongly correlated material SmB6 may be a realization of a topological Kondo insulator. We have performed an angle-resolved photoemission spectroscopy study on SmB6 in order to elucidate elements of the electronic structure relevant to the possible occurrence of a topological Kondo insulator state. The obtained electronic structure in the whole three-dimensional momentum space reveals one electron-like 5d bulk band centered at the X point of the bulk Brillouin zone that is hybridized with strongly correlated f electrons, as well as the opening of a Kondo band gap (Delta(B) similar to 20 meV) at low temperature. In addition, we observe electron-like bands forming three Fermi surfaces at the center Gamma point and boundary (X) over bar point of the surface Brillouin zone. These bands are not expected from calculations of the bulk electronic structure, and their observed dispersion characteristics are consistent with surface states. Our results suggest that the unusual low-temperature transport behavior of SmB6 is likely to be related to the pronounced surface states sitting inside the band hybridization gap and/or the presence of a topological Kondo insulating state.
Physica C-superconductivity and Its Applications | 1995
C. V. Tomy; Geetha Balakrishnan; D. McK. Paul
Specific heat and magnetization measurements have been carried out under a range of magnetic fields on single crystals of Ca 3 Co 2 O 6 . This compound is composed of Ising magnetic chains that are arranged on a triangular lattice. The intrachain and interchain couplings are ferromagnetic and antiferromagnetic, respectively. This situation gives rise to geometrical frustration, that bears some similarity to the classical problem of a two-dimensional Ising triangular antiferromagnet. This paper reports on the ordering process at low T and the possibility of one-dimensional features at high T.
Physica C-superconductivity and Its Applications | 1992
Ray Dupree; A. Gencten; D. McK. Paul
Abstract The phase diagrams for the binary and ternary Nd 2 O 3 -CuO and (0.85Nd 2 O 3 -0.3CeO 2 )- CuO systems are reported and the eutectic points and the liquid lines are determined. We have also explored the crystal growth from molten solutions of compositions 70% CuO-(30- z )% Nd 2 O 3 - z % CeO 2 for a range of CeO 2 concentrations. We show that the composition of the crystals is not uniform for a given z value but the compositional range appears to be quite narrow ( x =0.17(3)) for z =3.6. This concentration produces also the largest crystals (≈10 X 10 X 0.3 mm 3 ).
Journal of Crystal Growth | 2003
Geetha Balakrishnan; Martin R. Lees; D. McK. Paul
We have measured far infrared reflection and Raman spectra on high quality single crystals and ceramic samples of the Nd2−xCexCuO4 system. The TO and LO frequencies of all infrared-active phonons were determined from a Kramers-Kronig analysis of the infrared reflection spectra. The frequencies of the detected Raman-active phonons are 228 cm−1 (A1g Nd), 328 cm−1 (B1g O2) and 480 cm−1 (Eg 02). A resonantly enhanced peak at 580 cm−1 is observed for Ce-doped samples only with polarization properties like an A1g phonon. We have also performed lattice-dynamical calculations with parameters extracted from those of perovskites and metallic oxides. The frequencies obtained agree well with our experimental findings. We present the eigenvectors of all zone center phonons. Finally, we also detected a feature at 165 cm−1 in the ab-polarized infrared spectra in Nd2CuO4 which might be of magnetic origin.
Physical Review B | 2000
O. A. Petrenko; G. Balakrishnan; Martin R. Lees; D. McK. Paul; Andreas Hoser
A magnetic field induced insulator to metal transition has been observed in both polycrystalline and single crystals samples of Pr0.7Ca0.3MnO3. Application of a magnetic field leads to a first-order phase transition from an insulating to a conducting state at low temperatures. The hysteresis associated with this transition allows the resistivity at 4 K to be varied by more than eight orders of magnitude depending on the field history of the sample.