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Nonequilibrium steady state conditions induced by a dc current can alter the physical properties of strongly correlated electron systems. In this regard, it was recently shown that dc current can trigger novel electronic states, such as current-induced diamagnetism, which cannot be realized in equilibrium conditions. However, reversible control of diamagnetism has not been achieved yet. Here, we demonstrate reversible in situ control between a Mott insulating state and a diamagnetic semimetal-like state by a dc current in the Ti-substituted bilayer ruthenate ${\mathrm{Ca}}_{3}({\mathrm{Ru}}_{1\ensuremath{-}x}{\mathrm{Ti}}_{x}{)}_{2}{\mathrm{O}}_{7}$ ($x=0.5%$). By performing simultaneous magnetic and resistive measurements, we map out the temperature vs current-density phase diagram in the nonequilibrium steady state of this material. The present results open up the possibility of creating novel electronic states in a variety of strongly correlated electron systems under dc current.

Nonequilibrium steady state conditions induced by a dc current can alter the physical properties of strongly correlated electron systems. In this regard, it was recently shown that dc current can trigger novel electronic states, such as current-induced diamagnetism, which cannot be realized in equilibrium conditions. However, reversible control of diamagnetism has not been achieved yet. Here, we demonstrate reversible in situ control between a Mott insulating state and a diamagnetic semimetal-like state by a dc current in the Ti-substituted bilayer ruthenate Ca_{3}(Ru_{1-x}Ti_{x})_{2}O_{7} (x=0.5%). By performing simultaneous magnetic and resistive measurements, we map out the temperature vs current-density phase diagram in the nonequilibrium steady state of this material. The present results open up the possibility of creating novel electronic states in a variety of strongly correlated electron systems under dc current.

We employ a combination of chemical substitution and angle resolved photoemission spectroscopy to prove that the Fermi level in the $\ensuremath{\gamma}$ band of ${\mathrm{Sr}}_{2\ensuremath{-}y}{\mathrm{La}}_{y}{\mathrm{RuO}}_{4}$ can be made to traverse a van Hove singularity. Remarkably, the large mass renormalization has little dependence on either $\mathbf{k}$ or doping. By combining the results from photoemission with thermodynamic measurements on the same batches of crystals, we deduce a parametrization of the full many-body quasiparticle dispersion in ${\mathrm{Sr}}_{2}{\mathrm{RuO}}_{4}$ which extends from the Fermi level to approximately 20 meV above it.

High-resolution angular resolved photoemission data reveal well-defined quasiparticle bands of unusually low weight, emerging in line with the metallic phase of Ca(3)Ru(2)O(7) below approximately 30 K . At the bulk structural phase transition temperature of 48 K, we find clear evidence for an electronic instability, gapping large parts of the underlying Fermi surface that appears to be nested. Metallic pockets are found to survive in the small, non-nested sections, constituting a low-temperature Fermi surface with 2 orders of magnitude smaller volume than in all other metallic ruthenates. The Fermi velocities and volumes of these pockets are in agreement with the results of complementary quantum oscillation measurements on the same crystal batches.

We report a study of the de Haas-van Alphen (dHvA) effect on the itinerant metamagnet Sr3Ru2O7. Extremely high sample purity allows the observation of dHvA oscillations both above and below the metamagnetic transition field of 7.9 T. The quasiparticle masses are fairly large away from the transition, and are enhanced by up to an extra factor of 3 as the transition is approached, but the Fermi surface topography change is quite small. The results are qualitatively consistent with a field-induced Stoner transition in which the mass enhancement is the result of critical fluctuations.

We report that the quasi-two-dimensional Fermi-liquid behavior of the spin-triplet superconductor Sr2RuO4 breaks down in the vicinity of the critical impurity concentration for the onset of magnetic order induced by nonmagnetic Ti4+ impurities. The non-Fermi-liquid behavior is interpreted in terms of the two-dimensional antiferromagnetic fluctuations, which arise mainly from the nesting within one of the Fermi-surface sheets. We argue against the main role of such magnetic fluctuations in the pairing mechanism.