PMID- 24097193
OWN - NLM
STAT- PubMed-not-MEDLINE
DCOM- 20140429
LR  - 20131010
IS  - 1361-648X (Electronic)
IS  - 0953-8984 (Linking)
VI  - 25
IP  - 43
DP  - 2013 Oct 30
TI  - Low-temperature structure anomalies in CuNCN. Manifestations of RVB phase 
      transitions?
PG  - 435602
LID - 10.1088/0953-8984/25/43/435602 [doi]
AB  - We propose a new frustrated Heisenberg antiferromagnetic model with spatially 
      anisotropic exchange parameters Jc, Ja, and Jac, extending along the c, a, and a 
      +/- c (c-a-ca model) lattice directions, and apply it to describe the fascinating 
      physics of copper carbodiimide, CuNCN, assuming the resonating valence bond (RVB) 
      type of its phases. This explains within a unified picture the intriguing absence 
      of magnetic order in CuNCN. We further present a parameters-temperature phase 
      diagram of the c-a-ca-RVB model in the high-temperature approximation. Eight 
      different phases including Curie and Pauli paramagnets (respectively, in 
      disordered and 1D- or Q1D-RVB phases) and (pseudo)gapped (quasi-Arrhenius) 
      paramagnets (2D-RVB phases) are possible. By adding magnetostriction and elastic 
      terms to the model, we derive possible structural manifestations of RVB phase 
      transitions. Assuming a sequence of RVB phase transitions to occur in CuNCN with 
      decreasing temperature, several anomalies observed in the temperature course of 
      the lattice constants are explained.
FAU - Tchougreeff, A L
AU  - Tchougreeff AL
AD  - Institut fur anorganische Chemie RWTH-Aachen University, Landoltweg 1, D-52056, 
      Aachen, Germany.
FAU - Dronskowski, R
AU  - Dronskowski R
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20131004
PL  - England
TA  - J Phys Condens Matter
JT  - Journal of physics. Condensed matter : an Institute of Physics journal
JID - 101165248
EDAT- 2013/10/08 06:00
MHDA- 2013/10/08 06:01
CRDT- 2013/10/08 06:00
PHST- 2013/10/08 06:00 [entrez]
PHST- 2013/10/08 06:00 [pubmed]
PHST- 2013/10/08 06:01 [medline]
AID - 10.1088/0953-8984/25/43/435602 [doi]
PST - ppublish
SO  - J Phys Condens Matter. 2013 Oct 30;25(43):435602. doi: 
      10.1088/0953-8984/25/43/435602. Epub 2013 Oct 4.