Topic
Spin-½
About: Spin-½ is a research topic. Over the lifetime, 40423 publications have been published within this topic receiving 796639 citations.
Papers published on a yearly basis
Papers
More filters
TL;DR: Measurements reveal a magnetic quantum critical point where superconductivity first appears, consistent with an exotic quantum phase transition between the two phases, and demonstrate that the pseudogap phenomenon in the electron-doped materials arises from a build-up of spin correlations, in agreement with recent theoretical proposals.
Abstract: High-transition-temperature (high-T(c)) superconductivity develops near antiferromagnetic phases, and it is possible that magnetic excitations contribute to the superconducting pairing mechanism. To assess the role of antiferromagnetism, it is essential to understand the doping and temperature dependence of the two-dimensional antiferromagnetic spin correlations. The phase diagram is asymmetric with respect to electron and hole doping, and for the comparatively less-studied electron-doped materials, the antiferromagnetic phase extends much further with doping and appears to overlap with the superconducting phase. The archetypal electron-doped compound Nd2-xCexCuO4+/-delta (NCCO) shows bulk superconductivity above x approximately 0.13 (refs 3, 4), while evidence for antiferromagnetic order has been found up to x approximately 0.17 (refs 2, 5, 6). Here we report inelastic magnetic neutron-scattering measurements that point to the distinct possibility that genuine long-range antiferromagnetism and superconductivity do not coexist. The data reveal a magnetic quantum critical point where superconductivity first appears, consistent with an exotic quantum phase transition between the two phases. We also demonstrate that the pseudogap phenomenon in the electron-doped materials, which is associated with pronounced charge anomalies, arises from a build-up of spin correlations, in agreement with recent theoretical proposals.
190 citations
TL;DR: A bulk half-integer quantum Hall effect in a layered antiferromagnet EuMnBi2, in which field-controllable Eu magnetic order significantly suppresses the interlayer coupling between the Bi layers with Dirac fermions, will pave a route to the engineering of magnetically functionalized Dirac materials.
Abstract: For the innovation of spintronic technologies, Dirac materials, in which low-energy excitation is described as relativistic Dirac fermions, are one of the most promising systems because of the fascinating magnetotransport associated with extremely high mobility. To incorporate Dirac fermions into spintronic applications, their quantum transport phenomena are desired to be manipulated to a large extent by magnetic order in a solid. We report a bulk half-integer quantum Hall effect in a layered antiferromagnet EuMnBi2, in which field-controllable Eu magnetic order significantly suppresses the interlayer coupling between the Bi layers with Dirac fermions. In addition to the high mobility of more than 10,000 cm(2)/V s, Landau level splittings presumably due to the lifting of spin and valley degeneracy are noticeable even in a bulk magnet. These results will pave a route to the engineering of magnetically functionalized Dirac materials.
190 citations
TL;DR: In this article, a stroboscopic X-ray diffraction imaging technique was proposed for spin-strain coupling for various defects in silicon carbide with C3v symmetry.
Abstract: Hybrid spin-mechanical systems provide a platform for integrating quantum registers and transducers. Efficient creation and control of such systems require a comprehensive understanding of the individual spin and mechanical components as well as their mutual interactions. Point defects in silicon carbide (SiC) offer long-lived, optically addressable spin registers in a wafer-scale material with low acoustic losses, making them natural candidates for integration with high quality factor mechanical resonators. Here, we show Gaussian focusing of a surface acoustic wave in SiC, characterized by a novel stroboscopic X-ray diffraction imaging technique, which delivers direct, strain amplitude information at nanoscale spatial resolution. Using ab initio calculations, we provide a more complete picture of spin-strain coupling for various defects in SiC with C3v symmetry. This reveals the importance of shear for future device engineering and enhanced spin-mechanical coupling. We demonstrate all-optical detection of acoustic paramagnetic resonance without microwave magnetic fields, relevant to sensing applications. Finally, we show mechanically driven Autler-Townes splittings and magnetically forbidden Rabi oscillations. These results offer a basis for full strain control of three-level spin systems.
190 citations
TL;DR: In this paper, the authors proposed a scheme for perfect quantum communication through spin-chain channels with a probability of failure lower than P in a Heisenberg chain of N spin-(1/2) particles.
Abstract: We suggest a protocol for perfect quantum communication through spin-chain channels. By combining a dual-rail encoding with measurements only at the receiving end, we can get conclusively perfect state transfer, whose probability of success can be made arbitrarily close to unity. As an example of such an amplitude-delaying channel, we show how two parallel Heisenberg spin chains can be used as quantum wires. Perfect state transfer with a probability of failure lower than P in a Heisenberg chain of N spin-(1/2) particles can be achieved in a timescale of the order of (0.33({Dirac_h}/2{pi})/J)N{sup 1.7} vertical bar ln P vertical bar. We demonstrate that our scheme is more robust to decoherence and nonoptimal timing than any scheme using single spin chains.
189 citations
TL;DR: In this article, the suitability of different contact types for spin injection is discussed together with a review of possible detection mechanisms that can be used in the experiment, and the first estimate of the injection efficiency can easily be obtained without complicated calculations.
Abstract: Spintronics is a topic that has raised a lot of interest during the past years. The transport and manipulation of spin polarized electrons or holes in semiconductors offers a huge potential for novel devices that combine non-volatile information storage with high processing speed at low power, and which may even be useful for quantum computation. However, one major ingredient that has been missing for a long time is the transfer of spin polarized carriers from a magnetic contact into a non-magnetic semiconductor. Highly efficient electrical spin injection was realized for the first time in 1999 (Fiederling R et al Nature 402 787). Since then, several experiments have successfully demonstrated spin injection into semiconductors and additional concepts for spin filters and spin aligners have been proposed. Some of the experiments also yielded high spin injection efficiencies; however, in other experiments no unambiguous results could be obtained, and for many of the proposed concepts even a proof of principle is still missing. In this review, the suitability of different contact types for spin injection will be discussed together with a review of possible detection mechanisms that can be used in the experiment. By using a simple model based on load-lines we will show that for most spin aligners a first estimate of the injection efficiency can easily be obtained without complicated calculations.
189 citations