By combining Argos drifter buoys and TOPEX/POSEIDON altimeter data, the time series of sea-surface velocity fields in the Kuroshio Current (KC) and adjacent regions are established. And the variability of the KC from ...By combining Argos drifter buoys and TOPEX/POSEIDON altimeter data, the time series of sea-surface velocity fields in the Kuroshio Current (KC) and adjacent regions are established. And the variability of the KC from the Luzon Strait to the Tokara Strait is studied based on the velocity fields. The results show that the dominant variability period varies in different segments of the KC: The primary period near the Luzon Strait and to the east of Taiwan Island is the intra-seasonal time scale; the KC on the continental shelf of the ECS is the steadiest segment without obvious periodicity, while the Tokara Strait shows the period of seasonal variability. The diverse periods are caused by the Rossby waves propagating from the interior ocean, with adjustments in topography of island chain and local wind stress.展开更多
Spontaneous symmetry breaking has been a paradigm to describe the phase transitions in condensed matter physics.In addition to the continuous electromagnetic gauge symmetry,an unconventional superconductor can break d...Spontaneous symmetry breaking has been a paradigm to describe the phase transitions in condensed matter physics.In addition to the continuous electromagnetic gauge symmetry,an unconventional superconductor can break discrete symmetries simultaneously,such as time reversal and lattice rotational symmetry.In this work we report a characteristic in-plane 2-fold behaviour of the resistive upper critical field and point-contact spectra on the superconducting semimetal PbTaSe2 with topological nodal-rings,despite its hexagonal lattice symmetry(or D3 h in bulk while C3 v on surface,to be precise).The 2-fold behaviour persists up to its surface upper critical field Hc2R even though bulk superconductivity has been suppressed at its bulk upper critical field Hc2HC<<Hc2R,signaling its probable surface-only electronic nematicity.In addition,we do not observe any lattice rotational symmetry breaking signal from field-angle-dependent specific heat within the resolution.It is worth noting that such surface-only electronic nematicity is in sharp contrast to the observation in the topological superconductor candidate,CuxBi2Se3,where the nematicity occurs in various bulk measurements.In combination with theory,superconducting nematicity is likely to emerge from the topological surface states of PbTaSe2,rather than the proximity effect.The issue of time reversal symmetry breaking is also addressed.Thus,our results on PbTaSe2 shed new light on possible routes to realize nematic superconductivity with nontrivial topology.展开更多
基金Supported by the National Basic Research Program of China (973 Program, Nos. 2007CB411804, 2005CB422303)the NSFC (No. 40706006)+2 种基金the Key Project of International Science and Technology Cooperation Program of China (No. 2006DFB21250)the "111 Project" (B07036)the Program for New Century Excellent Talents in University (NECT-07-0781)
文摘By combining Argos drifter buoys and TOPEX/POSEIDON altimeter data, the time series of sea-surface velocity fields in the Kuroshio Current (KC) and adjacent regions are established. And the variability of the KC from the Luzon Strait to the Tokara Strait is studied based on the velocity fields. The results show that the dominant variability period varies in different segments of the KC: The primary period near the Luzon Strait and to the east of Taiwan Island is the intra-seasonal time scale; the KC on the continental shelf of the ECS is the steadiest segment without obvious periodicity, while the Tokara Strait shows the period of seasonal variability. The diverse periods are caused by the Rossby waves propagating from the interior ocean, with adjustments in topography of island chain and local wind stress.
基金the National Key R&D Program of China(2016FYA0300402 and 2017YFA0303101)the National Natural Science Foundation of China(NSFC)(11674279 and 11374257)+8 种基金supported in part by the NSFC(U1732162 and 11974061)support from the Zhejiang Provincial Natural Science Foundation(LR18A04001)supported in part by the National Key Research and Development Program of China(2016YFA0300202)the National Natural Science Foundation of China(11774306)the Strategic Priority Research Program of Chinese Academy of Sciences(XDB28000000)partly supported by KAKENHI(JP20H05164,19K14661,15H05883,18H01161,and JP17K05553)from JSPS‘‘JPhysics”(18H04306)financial support provided by the Project Number MOST-108-2112-M-001-049-MY2the Academia Sinica for the budget of AS-iMATE-109-13。
文摘Spontaneous symmetry breaking has been a paradigm to describe the phase transitions in condensed matter physics.In addition to the continuous electromagnetic gauge symmetry,an unconventional superconductor can break discrete symmetries simultaneously,such as time reversal and lattice rotational symmetry.In this work we report a characteristic in-plane 2-fold behaviour of the resistive upper critical field and point-contact spectra on the superconducting semimetal PbTaSe2 with topological nodal-rings,despite its hexagonal lattice symmetry(or D3 h in bulk while C3 v on surface,to be precise).The 2-fold behaviour persists up to its surface upper critical field Hc2R even though bulk superconductivity has been suppressed at its bulk upper critical field Hc2HC<<Hc2R,signaling its probable surface-only electronic nematicity.In addition,we do not observe any lattice rotational symmetry breaking signal from field-angle-dependent specific heat within the resolution.It is worth noting that such surface-only electronic nematicity is in sharp contrast to the observation in the topological superconductor candidate,CuxBi2Se3,where the nematicity occurs in various bulk measurements.In combination with theory,superconducting nematicity is likely to emerge from the topological surface states of PbTaSe2,rather than the proximity effect.The issue of time reversal symmetry breaking is also addressed.Thus,our results on PbTaSe2 shed new light on possible routes to realize nematic superconductivity with nontrivial topology.
