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We report the results of low temperature transport, specific heat, and magnetization measurements on high quality single crystals of the bilayer perovskite ${\mathrm{Sr}}_{3}{\mathrm{Ru}}_{2}{\mathrm{O}}_{7}$, which is a close relative of the unconventional superconductor ${\mathrm{Sr}}_{2}{\mathrm{RuO}}_{4}$. Metamagnetism is observed, and transport and thermodynamic evidence for associated critical fluctuations is presented. These relatively unusual fluctuations might be pictured as variations in the Fermi surface topography itself.

Recent experimental results indicate that superconductivity in Sr2RuO4 is described by the p-wave E_u representation of the D_{4h} point group. Results on the vortex lattice structures for this representation are presented. The theoretical results are compared with experiment., Comment: 4 pages, 3 figures, M2S-HTSC-VI proceedings

We have measured the diffracted neutron scattering intensities from the square magnetic flux lattice in the perovskite superconductor ${\mathrm{Sr}}_{2}{\mathrm{RuO}}_{4}$, which is thought to exhibit $p$-wave pairing with a two-component order parameter. The relative intensities of different flux lattice Bragg reflections over a wide range of field and temperature have been shown to be inconsistent with a single component Ginzburg-Landau theory but qualitatively agree with a two-component $p$-wave Ginzburg-Landau theory.

The phenomenon of superconductivity continues to be of considerable scientific and practical interest. Underlying this phenomenon is the formation of electron pairs, which in conventional superconductors do not rotate about their centre of mass (‘s -wave’ pairing; refs 1, 2). This contrasts with the situation in high-temperature superconductors, where the electrons in a pair are believed to have two units of relative angular momentum (‘d -wave’ pairing; ref. 3 and references therein). Here we report small-angle neutron-scattering measurements of magnetic flux lines in the perovskite superconductor Sr2RuO4 (ref. 4), which is a candidate for another unconventional paired electron state—‘p -wave’ pairing, which has one unit of angular momentum5,6,7. We find that the magnetic flux lines form a square lattice over a wide range of fields and temperatures, which is the result predicted by a recent theory8,9 of p -wave superconductivity in Sr2RuO4. This theory also indicates that only a fraction of the electrons are strongly paired and that the orientation of the square flux lattice relative to the crystal lattice will determine which parts of the three-sheet Fermi surface of this material are responsible for superconductivity. Our results suggest that superconductivity resides mainly on the ‘γ’ sheet9.

We report the observation of quantum oscillations in the electrical resistivity of a high-quality thin film of the itinerant ferromagnet ${\mathrm{SrRuO}}_{3}.$ Our study demonstrates the existence of long-lived fermion quasiparticles at low temperatures, and strongly suggests that the ground state of ${\mathrm{SrRuO}}_{3}$ is a Fermi liquid, even though ac and dc conductivity measurements at higher temperatures show anomalous metallic behavior. The implications of these results are discussed.

We report a neutron diffraction study of the induced moments at the metamagnetic transition observed at low temperature in the bilayer perovskite Sr3Ru2O7. This compound is a close relative of the unconventional superconductor Sr2RuO4.

We report the results of transport measurements on SrRuO3, Sr3Ru2O7, and CaRuO3 .I nSrRuO3 and Sr3Ru2O7, our findings are consistent with the predictions of Fermi liquid theory, in contrast to previous reports based on samples with much shorter mean free paths. In CaRuO3, however, a T 1.5 power law is seen in the resistivity in the high purity samples studied here. Our work gives concrete evidence that even the metallic state of the ruthenates is highly sensitive to disorder.

We report the results of low temperature transport, specific heat, and magnetization measurements on high quality single crystals of the bilayer perovskite Sr3Ru2O7, which is a close relative of the unconventional superconductor Sr2RuO4. Metamagnetism is observed, and transport and thermodynamic evidence for associated critical fluctuations is presented. These relatively unusual fluctuations might be pictured as variations in the Fermi surface topography itself.

We have measured the diffracted neutron scattering intensities from the square magnetic flux lattice in the perovskite superconductor Sr2RuO4, which is thought to exhibit p-wave pairing with a two-component order parameter. The relative intensities of different flux lattice Bragg reflections over a wide range of field and temperature have been shown to be inconsistent with a single component Ginzburg-Landau theory but qualitatively agree with a two-component p-wave Ginzburg-Landau theory.

The presence of Ru–O bilayers in the layered perovskite metal Sr3Ru2O7 could be intuitively expected to result in a doubling of the electronic structure of Sr2RuO4, i.e. four electron-like and two hole-like Fermi surface sheets. To check this, we have studied the weak-field Hall effect of Sr3Ru2O7 between 30 mK and 300 K. In contrast to the Hall coefficient in Sr2RuO4, which has two temperature dependent sign changes and is negative at low temperatures, that of Sr3Ru2O7 is positive over the whole range studied. Possible implications for its electronic structure are discussed.

Nature 396, 242–245 (1998) In this Letter, the X-ray Laue patterns used to give the orientation of our crystal were misinterpreted by 45°. With the magnetic field perpendicular to the RuO2 planes, the nearest-neighbour directions in the square flux-line lattice (FLL) are actually at 45° to the Ru–O–Ru directions in the crystal lattice.