Berlin 2015 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 72: Low-Dimensional Systems: Poster Session
TT 72.16: Poster
Mittwoch, 18. März 2015, 15:00–18:00, Poster B
Hints for a pressure-induced insulator-to-metal transition in low-dimensional CuNCN — •Estaline Amitha Francis1, H. Rosner2, and C. A. Kuntscher1 — 1Experimentalphysik 2, Universität Augsburg, D-86135 Augsburg, Germany — 2Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187 Dresden, Germany
Copper oxide compounds show fascinating properties such as high temperature superconductivity, cooperative Jahn-Teller effect, spin-Peierls magnetic, and cooperative magnetic states. Copper carbodiimide (CuNCN) is the nitrogen-based analog of cupric oxide, where the oxygen anion O2− is replaced with the isolobal carboiimide NCN2−, resulting in a distorted octahedral with first-order Jahn-Teller effect. Infrared high-pressure measurements on CuNCN were performed over the frequency range 500–6000 cm−1 to probe the insulator-to-metal transition. The infrared phonons of CuNCN at 595 and 696 cm−1 show significant pressure-dependent softening. The phonon mode at 595 cm−1 shows a two-fold splitting at 5 GPa (Pc1) and further splittings around 11 GPa (Pc2). The absorption edge is observed around 1200 cm−1 for 0.3 GPa and shows a strong red shift above Pc2. Furthermore, we observe a smearing out of the phonon spectra above Pc2. The changes in the absorption edge and the smearing out of phonons are indications for a pressure-induced insulator-to-metal transition in CuNCN.