Band Ordering and Dynamics of Cu2-xTe and Cu1.98Ag0.2Te


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SIRUSI A. A. , Ballikaya S. , CHEN J., Uher C., ROSS J. H.

JOURNAL OF PHYSICAL CHEMISTRY C, cilt.120, ss.14549-14555, 2016 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 120 Konu: 27
  • Basım Tarihi: 2016
  • Doi Numarası: 10.1021/acs.jpcc.6b04785
  • Dergi Adı: JOURNAL OF PHYSICAL CHEMISTRY C
  • Sayfa Sayıları: ss.14549-14555

Özet

63Cu, 65Cu, and 125Te NMR measurements are reported for
Cu2−xTe and Cu1.98Ag0.2Te. The results demonstrate an onset of Cu-ion
hopping below room temperature, including an activation behavior
consistent with high-temperature transport measurements but with a
significant enhancement of the hopping barriers with Ag substitution. We
also separated the Korringa behavior by combining NMR line shape and
relaxation measurements, thereby identifying large negative chemical shifts
for both nuclei, as well as large Cu and Te s-state contributions in the
valence band. Further comparison was obtained through heat capacity
measurements and chemical shifts computed by density functional
methods. The large diamagnetic chemical shifts coincide with behavior
previously identified for materials with topologically nontrivial band
inversion, and in addition, the large metallic shifts point to analogous
features in the valence band density of states, suggesting that Cu2Te may
have similar inverted features.