Browsing by Author "Perry, R. S."

We use high-resolution capacitive dilatometry to study the low-temperature linear magnetostriction of the bilayer ruthenate Sr3Ru2O7 as a function of magnetic field applied perpendicular to the ruthenium-oxide planes (B parallel to c). The relative length change Delta L(B)/L is detected either parallel or perpendicular to the c-axis close to the metamagnetic region near B = 8 T. In both cases, clear peaks in the coefficient lambda(B) = d(Delta L/L)/dB at three subsequent metamagnetic transitions are observed. For Delta L perpendicular to c, the third transition at 8.1 T bifurcates at temperatures below 0.5 K. This is ascribed to the effect of an in-plane uniaxial pressure of about 15 bar, unavoidable in the dilatometer, which breaks the original fourfold in-plane symmetry. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

We report high-resolution measurements of the in-plane thermal expansion anisotropy in the vicinity of the electronic nematic phase in Sr3Ru2O7 down to very low temperatures and in varying magnetic field orientation. For fields applied along the c-direction, a clear second-order phase transition is found at the nematic phase, with critical behavior compatible with the two-dimensional Ising universality class (although this is not fully conclusive). Measurements in a slightly tilted magnetic field reveal a broken fourfold in-plane rotational symmetry, not only within the nematic phase, but extending towards slightly larger fields. We also analyze the universal scaling behavior expected for a metamagnetic quantum critical point, which is realized outside the nematic region. The contours of the magnetostriction suggest a relation between quantum criticality and the nematic phase. (C) 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

We report measurements of quantum oscillations detected in the putative nematic phase of Sr3Ru2O7. Improvements in sample purity enabled the resolution of small amplitude de Haas-van Alphen (dHvA) oscillations between two first order metamagnetic transitions delimiting the phase. Two distinct frequencies were observed, whose amplitudes follow the normal Lifshitz-Kosevich profile. Variations of the dHvA frequencies are explained in terms of a chemical potential shift produced by reaching a peak in the density of states, and an anomalous field dependence of the oscillatory amplitude provides information on domains.

We report a detailed investigation of quantum oscillations in Sr3Ru2O7, observed inductively (the de Haas-van Alphen effect) and thermally (the magnetocaloric effect). Working at fields from 3 to 18 T allowed us to straddle the metamagnetic transition region and probe the low- and high-field Fermi liquids. The observed frequencies are strongly field dependent in the vicinity of the metamagnetic transition, and there is evidence for magnetic breakdown. We also present the results of a comprehensive rotation study. The most surprising result concerns the field dependence of the measured quasiparticle masses. Contrary to conclusions previously drawn by some of us as a result of a study performed with a much poorer signal-to-noise ratio, none of the five Fermi-surface branches for which we have good field-dependent data gives evidence for a strong-field dependence of the mass. The implications of these experimental findings are discussed.

The electronic nematic phase of Sr3Ru2O7 is investigated by high-resolution in-plane thermal expansion measurements in magnetic fields close to 8 T applied at various angles Theta off the c axis. At Theta < 10 degrees we observe a very small (10(-7)) lattice distortion which breaks the fourfold in-plane symmetry, resulting in nematic domains with interchanged a and b axis. At Theta greater than or similar to 10 degrees the domains are almost fully aligned and thermal expansion indicates an area-preserving lattice distortion of order 2 x 10(-6) which is likely related to orbital ordering. Since the system is located in the immediate vicinity of a metamagnetic quantum critical end point, the results represent the first observation of a structural relaxation driven by quantum criticality.