10,071 research outputs found

    Disorder from order among anisotropic next-nearest-neighbor Ising spin chains in SrHo2_2O4_4

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    We describe why Ising spin chains with competing interactions in SrHo2O4\rm SrHo_2O_4 segregate into ordered and disordered ensembles at low temperatures (TT). Using elastic neutron scattering, magnetization, and specific heat measurements, the two distinct spin chains are inferred to have N\'eel (↑↓↑↓\uparrow\downarrow\uparrow\downarrow) and double-N\'eel (↑↑↓↓\uparrow\uparrow\downarrow\downarrow) ground states respectively. Below TN=0.68(2)T_\mathrm{N}=0.68(2)~K, the N\'eel chains develop three dimensional (3D) long range order (LRO), which arrests further thermal equilibration of the double-N\'eel chains so they remain in a disordered incommensurate state for TT below TS=0.52(2)T_\mathrm{S}= 0.52(2)~K. SrHo2O4\rm SrHo_2O_4 distills an important feature of incommensurate low dimensional magnetism: kinetically trapped topological defects in a quasi−d−-d-dimensional spin system can preclude order in d+1d+1 dimensions.Comment: 10 pages, 10 figure

    Tomonaga-Luttinger Liquid Behavior and Spinon Confinement in YbAlO3_3

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    Low dimensional quantum magnets are interesting because of the emerging collective behavior arising from strong quantum fluctuations. The one-dimensional (1D) S = 1/2 Heisenberg antiferromagnet is a paradigmatic example, whose low-energy excitations, known as spinons, carry fractional spin S = 1/2. These fractional modes can be reconfined by the application of a staggered magnetic field. Even though considerable progress has been made in the theoretical understanding of such magnets, experimental realizations of this low-dimensional physics are relatively rare. This is particularly true for rare-earth based magnets because of the large effective spin anisotropy induced by the combination of strong spin-orbit coupling and crystal field splitting. Here, we demonstrate that the rare-earth perovskite YbAlO3_3 provides a realization of a quantum spin S = 1/2 chain material exhibiting both quantum critical Tomonaga-Luttinger liquid behavior and spinon confinement-deconfinement transitions in different regions of magnetic field-temperature phase diagram.Comment: Main text: 25 pages, 7 figures; Supplementary Information: 11 pages, 8 figure

    Infrastructure for Detector Research and Development towards the International Linear Collider

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    The EUDET-project was launched to create an infrastructure for developing and testing new and advanced detector technologies to be used at a future linear collider. The aim was to make possible experimentation and analysis of data for institutes, which otherwise could not be realized due to lack of resources. The infrastructure comprised an analysis and software network, and instrumentation infrastructures for tracking detectors as well as for calorimetry.Comment: 54 pages, 48 picture

    Pathfinding Fast Radio Bursts Localizations using Very Long Baseline Interferometry

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    Fast radio bursts (FRBs) are millisecond-duration, bright radio transients of extragalactic origin. The Canadian Hydrogen Intensity Mapping Experiment (CHIME) telescope’s CHIME/FRB instrument and other radio telescopes across the globe have detected hundreds of FRBs. Their origins are a mystery. Precise localization within the host is critical to distinguish between progenitor models. This can be achieved through Very Long Baseline Interferometry (VLBI). Until now, VLBI localizations have only been carried out in targeted follow-up observations of some repeating sources which comprise a small fraction of the FRBs. For this work, an interferometric array of 6m dishes was constructed at the Green Bank Observatory as a pathfinder to develop the necessary systems, technology, and techniques to enable VLBI on FRBs. This array called TONE has 8 instrumented dishes and works as a VLBI outrigger for CHIME on a \SI{\sim3300}{\kilo\meter} baseline. This involved construction, commissioning, and integration of the custom analog chains and digital system. TONE is pointed to shadow a portion of the CHIME primary beam at a fixed declination of \SI{22}{\deg}. Upon detection of a single dispersed pulse such as an FRB or a giant pulse from the Crab pulsar, CHIME alerts TONE, triggering a recording of buffered data to disk. In addition to TONE, a single 10-m dish at Algonquin Radio Observatory (ARO10) is set up with a similar infrastructure. Together they form the pathfinders for conducting VLBI for FRBs. We used these VLBI pathfinders to localize FRB 20210603A at the time of detection. The baseband data from CHIME and TONE are used to synthesize single beams at each telescope. The single-beam data from TONE and data from ARO10 are each cross-correlated with the single beam data from CHIME. We use the Crab pulsar for astrometric calibration and additionally correct for clock errors. The calibrated and corrected cross-correlated data is sampled with a likelihood function of the sky location and ionospheric effects using a Markov Chain Monte Carlo method to estimate the Right Ascension and Declination of the FRB. We localize the burst to SDSS J004105.82+211331.9, an edge-on quiescent lenticular galaxy at redshift z ≈0.177\approx 0.177. The localization, dispersion measure, rotation measure (RM), and temporal broadening are consistent with an observed line-of-sight through the host galactic disk, suggesting a progenitor from a population coincident with the host galactic plane. The development of the TONE telescope has enabled the localization of the FRB within the host. This is a key stepping stone towards constraining the origins and host environments of FRBs

    Resonant Elastic Soft X-Ray Scattering

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    Resonant (elastic) soft x-ray scattering (RSXS) offers a unique element, site, and valence specific probe to study spatial modulations of charge, spin, and orbital degrees of freedom in solids on the nanoscopic length scale. It cannot only be used to investigate single crystalline materials. This method also enables to examine electronic ordering phenomena in thin films and to zoom into electronic properties emerging at buried interfaces in artificial heterostructures. During the last 20 years, this technique, which combines x-ray scattering with x-ray absorption spectroscopy, has developed into a powerful probe to study electronic ordering phenomena in complex materials and furthermore delivers important information on the electronic structure of condensed matter. This review provides an introduction to the technique, covers the progress in experimental equipment, and gives a survey on recent RSXS studies of ordering in correlated electron systems and at interfaces

    Tomonaga–Luttinger liquid behavior and spinon confinement in YbAlO 3

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    Low dimensional quantum magnets are interesting because of the emerging collective behavior arising from strong quantum fluctuations. The one-dimensional (1D) S = 1/2 Heisenberg antiferromagnet is a paradigmatic example, whose low-energy excitations, known as spinons, carry fractional spin S = 1/2. These fractional modes can be reconfined by the application of a staggered magnetic field. Even though considerable progress has been made in the theoretical understanding of such magnets, experimental realizations of this low-dimensional physics are relatively rare. This is particularly true for rare-earth-based magnets because of the large effective spin anisotropy induced by the combination of strong spin–orbit coupling and crystal field splitting. Here, we demonstrate that the rare-earth perovskite YbAlO3 provides a realization of a quantum spin S = 1/2 chain material exhibiting both quantum critical Tomonaga–Luttinger liquid behavior and spinon confinement–deconfinement transitions in different regions of magnetic field–temperature phase diagram

    Measurements of direct CP violation

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    We review the experimental searches and determinations of direct CP violation in meson decays and other systems.Comment: 115 pages, 19 figure
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