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Creators/Authors contains: "Felser, Claudia"

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  1. Free, publicly-accessible full text available December 2, 2023
  2. Free, publicly-accessible full text available May 1, 2023
  3. Spin chains in solid state materials are quintessential quantum systems with potential applications in spin-based logic, memory, quantum communication, and computation. A critical challenge is the experimental determination of spin lifetimes with the ultimate goal of increasing it. Local measurements by scanning tunneling microscopy (STM) have demonstrated the importance of decoupling spins from their environment, with markedly improved lifetimes in spin chains on the surfaces of band insulators. In this work we use low-temperature scanning tunneling microscopy to reveal long-lifetime excitations in a chain of spin-1/2 electrons embedded in a charge density wave Mott insulator, 1T-TaS 2 . Naturally occurring domain walls trap chains of localized spin-1/2 electrons in nearby sites, whose energies lie inside the Mott gap. Spin-polarized measurements on these sites show distinct two-level switching noise, as well as negative differential resistance in the dI/dV spectra, typically associated with spin fluctuations. The excitations show exceptionally long lifetimes of a few seconds at 300 mK. Our work suggests that layered Mott insulators in the chalcogenide family, which are amenable to exfoliation and lithography, may provide a viable platform for quantum applications.
    Free, publicly-accessible full text available May 31, 2023
  4. Free, publicly-accessible full text available April 1, 2023
  5. Free, publicly-accessible full text available March 1, 2023
  6. Free, publicly-accessible full text available March 31, 2023
  7. Abstract

    The physical realization of Chern insulators is of fundamental and practical interest, as they are predicted to host the quantum anomalous Hall (QAH) effect and topologically protected chiral edge states which can carry dissipationless current. Current realizations of the QAH state often require complex heterostructures and sub-Kelvin temperatures, making the discovery of intrinsic, high temperature QAH systems of significant interest. In this work we show that time-reversal symmetry breaking Weyl semimetals, being essentially stacks of Chern insulators with inter-layer coupling, may provide a new platform for the higher temperature realization of robust chiral edge states. We present combined scanning tunneling spectroscopy and theoretical investigations of the magnetic Weyl semimetal, Co3Sn2S2. Using modeling and numerical simulations we find that depending on the strength of the interlayer coupling, chiral edge states can be localized on partially exposed kagome planes on the surfaces of a Weyl semimetal. Correspondingly, our dI/dVmaps on the kagome Co3Sn terraces show topological states confined to the edges which display linear dispersion. This work provides a new paradigm for realizing chiral edge modes and provides a pathway for the realization of higher temperature QAH effect in magnetic Weyl systems in the two-dimensional limit.