989 resultados para Spin reorientation
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The inelastic portion of the tunnel current through an individual magnetic atom grants unique access to read out and change the atom’s spin state, but it also provides a path for spontaneous relaxation and decoherence. Controlled closure of the inelastic channel would allow for the latter to be switched off at will, paving the way to coherent spin manipulation in single atoms. Here, we demonstrate complete closure of the inelastic channels for both spin and orbital transitions due to a controlled geometric modification of the atom’s environment, using scanning tunneling microscopy (STM). The observed suppression of the excitation signal, which occurs for Co atoms assembled into chains on a Cu2N substrate, indicates a structural transition affecting the dz2 orbital, effectively cutting off the STM tip from the spin-flip cotunneling path.
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We study the spin waves of the triangular skyrmion crystal that emerges in a two-dimensional spin lattice model as a result of the competition between Heisenberg exchange, Dzyalonshinkii–Moriya interactions, Zeeman coupling and uniaxial anisotropy. The calculated spin wave bands have a finite Berry curvature that, in some cases, leads to non-zero Chern numbers, making this system topologically distinct from conventional magnonic systems. We compute the edge spin-waves, expected from the bulk-boundary correspondence principle, and show that they are chiral, which makes them immune to elastic backscattering. Our results illustrate how topological phases can occur in self-generated emergent superlattices at the mesoscale.
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The Joint Plan of Action agreed upon with Iran on 24 November 2013 gave negotiators one year to forge a comprehensive agreement that restricts the country’s ability to militarise its nuclear programme. That deadline will lapse in the next few days and diplomats involved in the talks have been trying to rein in expectations that a deal will be struck on time. Satisfying domestic constituencies in Iran and the US is what makes the politics of dealing with the nuclear file so much harder than the physics of slowing down the nuclear programme. Any future deal will have to stand on its own merits, enabling Iran and the EU3+3 to cooperate on the other geopolitical challenges they face. Both parties should therefore balance their demands with what they can realistically offer and make concessions to reach a compromise. The author of this CEPS Commentary argues that if no deal is reached on November 24th, then diplomacy should be allowed to keep on spinning for a few more months.
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Work performed at the Argonne National Laboratory.
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Transportation Department, Office of University Research, Washington, D.C.
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Mode of access: Internet.
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"This group report is based on an article submitted to the Physical review."
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Includes index.
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Mode of access: Internet.
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"June 1973."
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"August 1974."