Features of Chirality Generated by Paramagnetic Coupling to Magnetic Fields in the 3 K-Phase of Sr2RuO4

• Published in: Proceedings of the International Conference on Strongly Correlated Electron Systems (SCES2019)
• Main Authors: Kaneyasu Hirono, Enokida Yuya, Nomura Takuji, Hasegawa Yasumasa, Sakai Toru, Sigrist Manfred
• Format: Conference Object
• Language: English
• Published: 2020
• Subjects: IPY
• Online Access: https://repo.qst.go.jp/?action=repository_uri&item_id=79636; http://id.nii.ac.jp/1657/00079618/

Eutectic Sr2RuO4-Ru samples show an onset of inhomogeneous superconductivity at around 3 K, which is above the bulk transition of Sr2RuO4 (SRO) with Tc≈1.5Tc≈1.5 K. This superconducting state nucleates most likely as a filamentary state at the interface between SRO and Ru-inclusions. Assuming that the superconducting phase of SRO has chiral symmetry, the evolution towards the bulk phase involves an additional symmetry breaking transition. Phenomenological theories based on a two-component order parameter (ηxηx, ηyηy) suggest that first a time reversal symmetry conserving order parameter nucleates at the interface due to the symmetry reduction. A second transition yields a time reversal symmetry breaking phase through the appearance of a second order parameter component. In this study we show how this second transition can be influenced by external magnetic fields. For fields parallel to the basal plane of SRO the transition is suppressed. On the other hand, fields along the c-axis support the second order parameter component. This behavior is well visible in quasi-particle tunneling spectroscopy where a zero-bias peak indicates the presence of the second order parameter component. Our result reproduces experimental results on a qualitative level very well and are compatible with both chiral superconducting phases, px±ipypx±ipy-wave (spin triplet) and dxz±idyzdxz±idyz-wave (spin singlet) pairing.