Strong increase in ultrasound attenuation below T2 in Sr2RuO4 : possible evidence for domains
Abstract
Recent experiments suggest that Sr2RuO4 has a two-component superconducting order parameter (OP). A two-component OP has multiple degrees of freedom in the superconducting state that can result in low-energy collective modes or the formation of domain walls—a possibility that would explain a number of experimental observations including the smallness of the signature of time reversal symmetry breaking at Tc and telegraph noise in critical current experiments. We use resonant ultrasound spectroscopy to perform ultrasound attenuation measurements across the superconducting Tc of Sr2RuO4. We find that compressional sound attenuation increases by a factor of 7 immediately below Tc , in sharp contrast with what is found in both conventional (s-wave) and high-Tc (d-wave) superconductors. Our observations are most consistent with the presence of domain walls that separate different configurations of the superconducting OP. The fact that we only observe an increase in sound attenuation for compressional strains, and not for shear strains, suggests an inhomogeneous superconducting state formed of two distinct, accidentally degenerate superconducting OPs that are not related to each other by symmetry. Whatever the mechanism, a factor of 7 increase in sound attenuation is a singular characteristic that must be reconciled with any potential theory of superconductivity in Sr2RuO4.
Citation
Ghosh , S , Kiely , T G , Shekhter , A , Jerzembeck , F , Kikugawa , N , Sokolov , D A , Mackenzie , A P & Ramshaw , B J 2022 , ' Strong increase in ultrasound attenuation below T 2 in Sr 2 RuO 4 : possible evidence for domains ' , Physical Review B , vol. 106 , no. 2 , 024520 . https://doi.org/10.1103/PhysRevB.106.024520
Publication
Physical Review B
Status
Peer reviewed
ISSN
2469-9969Type
Journal article
Rights
Copyright ©2022 American Physical Society. This work has been made available online in accordance with publisher policies or with permission. Permission for further reuse of this content should be sought from the publisher or the rights holder. This is the final published version of the work, which was originally published at https://doi.org/10.1103/PhysRevB.106.024520.
Description
Funding information: B.J.R. and S.G. acknowledge support from the Office of Basic Energy Sciences of the U.S. Department of Energy under award No. DE-SC0020143. B.J.R. and S.G. acknowledge support from the Cornell Center for Materials Research with funding from the Materials Research Science and Engineering Centers program of the National Science Foundation (cooperative agreement No. DMR-1719875). T.G.K. acknowledges support from the National Science Foundation under Grant No. PHY-2110250. N.K. acknowledges support from Japan Society for the Promotion of Science (JSPS) KAKENHI (Grants No. JP17H06136, No. JP18K04715, and No. 21H01033) and Japan Science and Technology Agency Mirai Program (JPMJMI18A3) in Japan.Collections
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