{'fraction_non_alphanumeric': 0.019447287615148412, 'fraction_numerical': 0.0010235414534288639, 'mean_word_length': 5.839160839160839, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Atomic motions in the layered copper pseudochalcogenide CuNCN indicative of a quantum spin-liquid scenario

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 ∝T2, speaking in favor of the spin-liquid picture of the electronic phases of CuNCN.