Intertwined Orders in Heavy-Fermion Superconductor CeCoIn5

Abstract

The appearance of spin-density-wave (SDW) magnetic order in the low-temperature and high-field corner of the superconducting phase diagram of CeCoIn 5 is unique among unconventional superconductors. The nature of this magnetic Q phase is a matter of current debate. Here, we present the thermal conductivity of CeCoIn 5 in a rotating magnetic field, which reveals the presence of an additional order inside the Q phase that is intimately intertwined with the superconducting d-wave and SDW orders. A discontinuous change of the thermal conductivity within the Q phase, when the magnetic field is rotated about antinodes of the superconducting d-wave order parameter, demands that the additional order must change abruptly, together with the recently observed switching of the SDW. A combination of interactions, where spin-orbit coupling orients the SDW, which then selects the secondary p-wave pair-density-wave component (with an average amplitude of 20% of the primary d-wave order parameter), accounts for the observed behavior.

Calorimetric Measurements of Magnetic-Field-Induced Inhomogeneous Superconductivity Above the Paramagnetic Limit

“…This transition was initially attributed to FFLO superconductivity but is now known to correspond to the onset of spin-density wave (SDW) ordering within the superconducting state [11][12][13][14]. Details of the SDW ordering observed by NMR have led to suggestions of a lower field FFLO transition [15] and/or coupling of a FFLO phase along H to this SDW transition [15][16][17], but there is no clear thermodynamic evidence for these proposals [14,18,19]. The possibility remains of a more complex coupling of the SDW transition to a modified FFLO phase or pair density wave (PDW) [15,19].…”

“…Details of the SDW ordering observed by NMR have led to suggestions of a lower field FFLO transition [15] and/or coupling of a FFLO phase along H to this SDW transition [15][16][17], but there is no clear thermodynamic evidence for these proposals [14,18,19]. The possibility remains of a more complex coupling of the SDW transition to a modified FFLO phase or pair density wave (PDW) [15,19]. More recently, an analog of the FFLO state in the continuously variable parameter space of trapped atoms has caught the interest of theorists and experimentalists stimulating a rich new area of research [20][21][22].…”

Disorder raises the critical temperature of a cuprate superconductor

“…Similarly, in Heavy Fermion compounds such as CeCoIn 5 , the interaction between SDW and d-wave superconductivity is still actively investigated. 72 This topic is also a staple of the dichalcogenides superconductors, in which CDW were first discovered. The case for competition is relatively well established in 2H-TaS 2 and 2H-TaSe 2 .…”

Single-atom fabrication with electron and ion beams: From surfaces and two-dimensional materials toward three-dimensional atom-by-atom assembly

“…Following the initial demonstration of single-atom sensitivity in EELS 38 and three-dimensional (3D) imaging capability via focal series, 39 the increased spatial resolution and sensitivity of STEM have enabled advances such as direct mapping of polarization, 40,41 in-plane octahedral tilts, 42 and chemical strains, 43,44 and was recently extended to probe tilt systems in the z-direction. 45 Advances in the quantification of STEM have determined the location of single vacancy centers, 46 and are likely to lead to further breakthroughs. In parallel with the mainstream development of STEM as a purely imaging/spectroscopy tool, a number of groups have explored the potential of atomically focused beams for resist-based lithography, 47,48 now approaching 1-nm resolution, and e-beam deposition.…”