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Pressure represents a clean tuning parameter for traversing the complex phase diagrams of interacting electron systems and as such has proved of key importance in the study of quantum materials. Application of controlled uniaxial pressure has recently been shown to more than double the transition temperature of the unconventional superconductor Sr$_{2}$RuO$_{4}$ for example, leading to a pronounced peak in $T_mathrm{c}$ vs. strain whose origin is still under active debate. Here, we develop a simple and compact method to apply large uniaxial pressures passively in restricted sample environments, and utilize this to study the evolution of the electronic structure of Sr$_{2}$RuO$_{4}$ using angle-resolved photoemission. We directly visualize how uniaxial stress drives a Lifshitz transition of the $gamma$-band Fermi surface, pointing to the key role of strain-tuning its associated van Hove singularity to the Fermi level in mediating the peak in $T_mathrm{c}$. Our measurements provide stringent constraints for theoretical models of the strain-tuned electronic structure evolution of Sr$_{2}$RuO$_{4}$. More generally, our novel experimental approach opens the door to future studies of strain-tuned phase transitions not only using photoemission, but also other experimental techniques where large pressure cells or piezoelectric-based devices may be difficult to implement.
We report a systematic study of electron doping of Sr2RuO4 by non-isovalent substitution of La^(3+) for Sr^(2+). Using a combination of de Haas-van Alphen oscillations, specific heat, and resistivity measurements, we show that electron doping leads t
We present the first measurement on Nernst effect in the normal state of odd-parity, spin-triplet superconductor Sr$_{2}$RuO$_{4}$. Below 100 K, the Nernst signal was found to be negative, large, and, as a function of magnetic field, nonlinear. Its m
The La-based 214 cuprates host several symmetry breaking phases including superconductivity, charge and spin order in the form of stripes, and a structural othorhombic-to-tetragonal phase transition. Therefore, these materials are an ideal system to
Uniaxial pressure applied along an Ru-Ru bond direction induces an elliptical distortion of the largest Fermi surface of Sr$_2$RuO$_4$, eventually causing a Fermi surface topological transition, also known as a Lifshitz transition, into an open Fermi
We find excitations lower in energy than known phonon modes in underdoped La$_{2-x}$Sr$_x$CuO$_{4+delta}$ (x=0.08), with both inelastic X-Ray scattering (IXS) and inelastic neutron scattering (INS). A non dispersive excitation at 9 meV is identified