Possible signatures of mixed-parity superconductivity in doped polar SrTiO3 films

Abstract

Superconductors that possess both broken spatial inversion symmetry and spin-orbit interactions exhibit a mix of spin singlet and triplet pairing. Here, we report on measurements of the superconducting properties of electron-doped, strained SrTiO3 films. These films have an enhanced superconducting transition temperature and were previously shown to undergo a transition to a polar phase prior to becoming superconducting. We show that some films show signatures of an unusual superconducting state, such as an in-plane critical field that is higher than both the paramagnetic and orbital pair breaking limits. Moreover, nonreciprocal transport, which reflects the ratio of odd versus even pairing interactions, is observed. Together, these characteristics indicate that these films provide a tunable platform for investigations of unconventional superconductivity.

References in corpus (23)

• Topological insulators and superconductors
• Fault-tolerant quantum computation by anyons
• Superconducting proximity effect and Majorana fermions at the surface of a topological insulator
• New directions in the pursuit of Majorana fermions in solid state systems
• Topological superconductors: a review
• Tunable Rashba spin-orbit interaction at oxide interfaces
• Superconducting 2D system with lifted spin degeneracy: Mixed singlet-triplet state
• Superconductivity and spin-orbit coupling in non-centrosymmetric materials: a review
• A Universal Critical Density Underlying the Physics of Electrons at the LaAlO3/SrTiO3 Interface
• A ferroelectric quantum phase transition inside the superconducting dome of Sr${}_{1-x}$Ca${}_x$TiO${}_{3-\delta }$
• Critical doping for the onset of a two-band superconducting ground state in SrTiO${}_{3-\delta }$
• Theory of t2g electron-gas Rashba interactions
• Nonreciprocal charge transport in two-dimensional noncentrosymmetric superconductors
• Odd-parity superconductivity in the vicinity of inversion symmetry breaking in spin-orbit-coupled systems
• Nonreciprocal current in noncentrosymmetric Rashba superconductors
• Topological superconductivity and unconventional pairing in oxide interfaces
• Shubnikov-de Haas effect in low electron density SrTiO3: Conduction band edge of SrTiO3 redux
• Intrinsic spin-orbit coupling in superconducting δ-doped SrTiO3 heterostructures
• Ferroelectric enhancement of superconductivity in compressively strained SrTiO${}_3$ films
• Spin-orbit-coupled ferroelectric superconductivity
• Multiorbital Ferroelectric Superconductivity in doped SrTiO3
• Tuning Rashba spin-orbit coupling at LaAlO3/SrTiO3 interfaces by band filling
• Upper critical field as a probe for multiband superconductivity in bulk and interfacial STO

Cited by in corpus (31)

• Intrinsic Superconducting Diode Effect
• Supercurrent diode effect and finite momentum superconductivity
• Superconducting diode effect and nonreciprocal transition lines
• Order-Disorder Ferroelectric Transition of Strained SrTiO3
• Topological metals and finite-momentum superconductors
• Anapole superconductivity from $\mathcal{P}\mathcal{T}$-symmetric mixed-parity interband pairing
• Nonreciprocal optical response in parity-breaking superconductors
• Field-Effect Josephson Diode via Asymmetric Spin-Momentum-Locking States
• Enhanced Critical Field of Superconductivity at an Oxide Interface
• Anomalous superconducting diode effect in a polar superconductor
• Theory of superconductivity mediated by Rashba coupling in incipient ferroelectrics
• Superconductivity enhancement in polar metal regions of Sr${}_{0.95}$Ba${}_{0.05}$TiO${}_3$ and Sr${}_{0.985}$Ca${}_{0.015}$TiO${}_3$ revealed by the systematic Nb doping
• Generalized Rashba Electron-Phonon Coupling and Superconductivity in Strontium Titanate
• Piezoelectric effect and diode effect in anapole and monopole superconductors
• Coexistence of superconductivity and weak anti-localization at KTaO3 (111) interfaces
• Rectification and nonlinear Hall effect by fluctuating finite-momentum Cooper pairs
• Superconducting piezoelectric effect
• Theoretical investigation of twin boundaries in WO${}_3$: Structure, properties and implications for superconductivity
• Linear optical response from the odd parity Bardasis-Schrieffer mode in locally non-centrosymmetric superconductors
• A theory of criticality for quantum ferroelectric metals
• Optimizing one dimensional superconducting diodes: Interplay of Rashba spin-orbit coupling and magnetic fields
• Effects of spin-orbit interaction and electron correlations in strontium titanate
• Non-Hermitian superconducting diode effect
• Majorana-Weyl cones in ferroelectric superconductors
• Superconductivity in tin telluride films grown by molecular beam epitaxy
• Modeling polar order in compressively strained SrTiO${}_3$
• Violation of Pauli Limit at KTaO3(110) Interfaces
• Nonreciprocal transport in U(1) gauge theory of high-Tc cuprates
• Gate-tunable Josephson diodes in magic-angle twisted bilayer graphene
• Effects of doping on polar order in SrTiO${}_3$ from first-principles modeling
• Field-free Superconducting Diode Effect and Topological Fulde-Ferrell Superconductivity in Altermagnetic Shiba Chains