Intertwining quantum order and non-trivial topology is at the frontier of condensed matter physics. A charge- density-wave-like order with orbital currents has been pro- posed for achieving the quantum anomalous Hall effect in topological materials and for the hidden phase in cuprate high-temperature superconductors. However, the experimental realization of such an order is challenging. Here we use high-resolution scanning tunnelling microscopy to discover an unconventional chiral charge order in a kagome material, KV3Sb5, with both a topological band structure and a superconducting ground state.
The silver ruthenium oxide AgRuO3 consists of honeycomb Ru25+O62− layers and can be considered and can be considered an analogue of SrRu2O6 with a different intercalation. We present measurements of magnetic susceptibility and specific heat on AgRuO3 single crystals, which reveal a sharp antiferromagnetic transition at 342(3) K. The electrical transport in single crystals of AgRuO3 is determined by a combination of activated conduction over an intrinsic semiconducting gap of ≈100 meV and carriers trapped and thermally released from defects.
Multiple quantum phase transitions of different nature in the topological kagome magnet Co3Sn2−xInxS2
The exploration of topological electronic phases that result from strong electronic correlations is a frontier in condensed matter physics. One class of systems that is currently emerging as a platform for such studies are so-called kagome magnets based on transition metals. Using muon spin-rotation, we explore magnetic correlations in the kagome magnet Co3Sn2−xInxS2 as a function of In-doping, providing putative evidence for an intriguing incommensurate helimagnetic (HM) state. Our results show that, while the undoped sample exhibits an out-of-plane ferromagnetic (FM) ground state, at 5% of In-doping the system enters a state in which FM and in-plane antiferromagnetic (AFM) phases coexist.
Chiral superconductors are novel topological materials with finite angular momentum Cooper pairs circulating around a unique chiral axis, thereby spontaneously breaking time-reversal symmetry. They are rather scarce and usually feature triplet pairing: a canonical example is the chiral p-wave state realized in the A-phase of superfluid He3. Chiral triplet super- conductors are, however, topologically fragile with the corresponding gapless boundary modes only weakly protected against symmetry-preserving perturbations in contrast to their singlet counterparts. Using muon spin relaxation measurements ...
Frustration-driven magnetic fluctuations as the origin of the low-temperature skyrmion phase in Co7Zn7Mn6
Magnetic skyrmions in chiral cubic helimagnets, are stabilized by thermal fluctuations over a narrow region directly below the magnetic ordering temperature. Due to often being touted for use in applications, there is high demand to identify new mechanism that can expand the equilibrium skyrmion phases where these topological vortices may display an enhanced robustness against external perturbations, such as magnetic fields, due to a larger magnetic order parameter.
Probing the superconducting gap structure in the noncentrosymmetric topological superconductor ZrRuAs
The superconducting gap structure of the topological superconductor candidate ZrRuAs with a noncen- trosymmetric crystal structure has been investigated using muon-spin rotation/relaxation (μSR) measurements in transverse-field (TF) and zero-field (ZF) geometries. Magnetization, electrical resistivity, and heat capacity measurements reveal bulk superconductivity below a superconducting transition temperature Tc = 7.9(1) K.
Combining magnetic and superconducting functionalities enables lower energy spin transfer and magnetic switching in quantum computing and information storage, owing to the dissipationless nature of quasi-particle mediated supercurrents. Here, we put forward a system where emergent spin-ordering and diffusion of Cooper pairs are achieved at a non-intrinsically magnetic nor superconducting metallo-molecular interface.
Strontium ruthenate (Sr2RuO4) continues to present an important test of our understanding of unconventional superconductivity, because while its normal-state electronic structure is known with precision, its superconductivity remains unexplained. There is evidence that its order parameter is chiral, but reconciling this with recent observations of the spin part of the pairing requires an order parameter that is either finely tuned or implies a new form of pairing. Therefore, a definitive resolution of whether the superconductivity of Sr2RuO4 is chiral is important for the study of superconductivity.
A better understanding of quantum spin liquids (QSLs), where spin dimer configurations are fluctuating even at the low- est temperatures, could be of use in quantum information, in superconducting or other technologies. This macroscopic collective state typically arises from geometrical frustration or low dimensionality. In the layered EDT-BCO, we report a QSL state, which is generated, on different bases, with the intrinsic disorder.