TY - JOUR
T1 - Momentum-resolved superconducting energy gaps of Sr2RuO4 from quasiparticle interference imaging
AU - Sharma, Rahul
AU - Edkins, Stephen D.
AU - Wang, Zhenyu
AU - Kostin, Andrey
AU - Sow, Chanchal
AU - Maeno, Yoshiteru
AU - Mackenzie, Andrew P.
AU - Séamus Davis, J. C.
AU - Madhavan, Vidya
N1 - We thank B. M. Andersen, P. Coleman, C. Hicks, B. Ramshaw, S. A. Kivelson, S. H. Simon, and A.-M. Tremblay for helpful discussions and communications. R.S. and A.K. acknowledge support from US Department of Energy, Office of Basic Energy Sciences Contract DEAC02-98CH10886. S.D.E. and J.C.S.D acknowledge support from Gordon and Betty Moore Foundation Emergent Phenomena in Quantum Systems Initiative Grant GBMF4544. Y.M. acknowledges support from Japan Society for the Promotion of Science (JSPS) and Grants-in-aid for scientific research (KAKENHI) Grants JP15H05851 and JP15K21717 and from the JSPS Core-to-Core Program. J.C.S.D. acknowledges support from Science Foundation Ireland Award SFI 17/RP/5445 and from European Research Council Award DLV-788932. V.M. acknowledges funding from US Department of Energy, Office of Basic Energy Sciences Award DE-SC0014335.
PY - 2020/3/10
Y1 - 2020/3/10
N2 - Sr2RuO4 has long been the focus of intense
research interest because of conjectures that it is a correlated
topological superconductor. It is the momentum space (k-space) structure of the superconducting energy gap Δi(k) on each band i
that encodes its unknown superconducting order parameter. However,
because the energy scales are so low, it has never been possible to
directly measure the Δi(k) of Sr2RuO4.
Here, we implement Bogoliubov quasiparticle interference (BQPI)
imaging, a technique capable of high-precision measurement of multiband Δi(k). At T = 90 mK, we visualize a set of Bogoliubov scattering interference wavevectors qj:j=1−5 consistent with eight gap nodes/minima that are all closely aligned to the (±1,±1)
crystal lattice directions on both the α and β bands. Taking these
observations in combination with other very recent advances in
directional thermal conductivity [E. Hassinger et al., Phys. Rev. X 7, 011032 (2017)], temperature-dependent Knight shift [A. Pustogow et al., Nature 574, 72–75 (2019)], time-reversal symmetry conservation [S. Kashiwaya et al., Phys. Rev B, 100, 094530 (2019)], and theory [A. T. Rømer et al., Phys. Rev. Lett. 123, 247001 (2019); H. S. Roising, T. Scaffidi, F. Flicker, G. F. Lange, S. H. Simon, Phys. Rev. Res. 1, 033108 (2019); and O. Gingras, R. Nourafkan, A. S. Tremblay, M. Côté, Phys. Rev. Lett. 123, 217005 (2019)], the BQPI signature of Sr2RuO4 appears most consistent with Δi(k) having dx2−y2 (B1g) symmetry.
AB - Sr2RuO4 has long been the focus of intense
research interest because of conjectures that it is a correlated
topological superconductor. It is the momentum space (k-space) structure of the superconducting energy gap Δi(k) on each band i
that encodes its unknown superconducting order parameter. However,
because the energy scales are so low, it has never been possible to
directly measure the Δi(k) of Sr2RuO4.
Here, we implement Bogoliubov quasiparticle interference (BQPI)
imaging, a technique capable of high-precision measurement of multiband Δi(k). At T = 90 mK, we visualize a set of Bogoliubov scattering interference wavevectors qj:j=1−5 consistent with eight gap nodes/minima that are all closely aligned to the (±1,±1)
crystal lattice directions on both the α and β bands. Taking these
observations in combination with other very recent advances in
directional thermal conductivity [E. Hassinger et al., Phys. Rev. X 7, 011032 (2017)], temperature-dependent Knight shift [A. Pustogow et al., Nature 574, 72–75 (2019)], time-reversal symmetry conservation [S. Kashiwaya et al., Phys. Rev B, 100, 094530 (2019)], and theory [A. T. Rømer et al., Phys. Rev. Lett. 123, 247001 (2019); H. S. Roising, T. Scaffidi, F. Flicker, G. F. Lange, S. H. Simon, Phys. Rev. Res. 1, 033108 (2019); and O. Gingras, R. Nourafkan, A. S. Tremblay, M. Côté, Phys. Rev. Lett. 123, 217005 (2019)], the BQPI signature of Sr2RuO4 appears most consistent with Δi(k) having dx2−y2 (B1g) symmetry.
KW - Quasiparticle interference
KW - Strontium ruthenate
KW - Superconducting energy gaps
U2 - 10.1073/pnas.1916463117
DO - 10.1073/pnas.1916463117
M3 - Article
C2 - 32094178
AN - SCOPUS:85081644355
SN - 0027-8424
VL - 117
SP - 5222
EP - 5227
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 10
ER -