Upper Critical Field of Sr${}_2$RuO${}_4$ under In-Plane Uniaxial Pressure

Abstract

In-plane uniaxial pressure has been shown to strongly tune the superconducting state of Sr2RuO4 by approaching a Lifshitz transition and associated Van Hove singularity (VHS) in the density of states. At the VHS, $T_c$ and the in- and out-of-plane upper critical fields are all strongly enhanced, and the latter has changed its curvature as a function of temperature from convex to concave. However, due to strain inhomogeneity it has not been possible so far to determine how the upper critical fields change with strain. Here, we show the strain dependence of both upper critical fields, which was achieved due to an improved sample preparation. We find that the in-plane upper critical field is mostly linear in $T_c$. On the other hand, the out-of-plane upper critical field varies with a higher power in $T_c$, and peaks strongly at the VHS. The strong increase in magnitude and the change in form of $H_{c2||c}$ occur very close to the Van Hove strain, and points to a strong enhancement of both the density of states and the gap magnitude at the Lifshitz transition.

References in corpus (6)

• Effects of Co substitution on thermodynamic and transport properties and anisotropic $H_{c2}$ in Ba(Fe${}_{1-x}$Co${}_x$)${}_2$As${}_2$ single crystals
• First-Order Superconducting Transition of Sr2RuO4
• Elastocaloric determination of the phase diagram of Sr${}_2$RuO${}_4$
• High sensitivity heat capacity measurements on Sr2RuO4 under uniaxial pressure
• The Superconductivity of Sr${}_2$RuO${}_4$ Under $c$-Axis Uniaxial Stress
• $T_c$ and Pauli limited critical field of ${\text{Sr}}_2\text{Ru}{\text{O}}_4$: uniaxial strain dependence

Cited by in corpus (5)

• Constraints on the superconducting state of Sr${}_2$RuO${}_4$ from elastocaloric measurements
• $T_c$ and the elastocaloric effect of Sr${}_2$RuO${}_4$ under $⟨110⟩$ uniaxial stress: no indications of transition splitting
• Competition between d-wave superconductivity and magnetism in uniaxially strained Sr2RuO4
• Low-dimensionality-induced tunable ferromagnetism in SrRuO${}_3$ ultrathin films
• Influence of Fermi Surface Geometry and Van Hove Singularities on the Optical Response of Sr${}_2$RuO${}_4$