Atomic motions in the layered copper pseudochalcogenide CuNCN indicative of a quantum spin-liquid scenarioстатья
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Дата последнего поиска статьи во внешних источниках: 26 декабря 2017 г.
Аннотация:We explore the thermodynamic properties of the layered copper(II) carbodiimide CuNCN
by heat-capacity measurements and investigate the corresponding thermal atomic motions
by means of neutron powder diffraction as well as inelastic neutron scattering. The
experiments are complemented by a combination of density-functional calculations, phonon
analysis and analytic theory. The existence of a soft flexural mode—bending of the layers,
characteristic for the material structure—is established in the phonon spectrum of CuNCN
by giving characteristic temperature-dependent contributions to the heat capacity and
atomic displacement parameters. The agreement with the neutron data allows us to extract a
residual—on top of the lattice—presumably spinon contribution to the heat capacity \propto T^2,
speaking in favor of the spin-liquid picture of the electronic phases of CuNCN.