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Title: Magnetic and dielectric properties of one-dimensional array of S = 1/2 linear trimer system Na{sub 2}Cu{sub 3}Ge{sub 4}O{sub 12}

Magnetic susceptibility χ, specific heat C, capacitance C{sub p}, and {sup 23}Na-NMR measurements have been carried out on polycrystalline samples of quantum spin linear trimer system Na{sub 2}Cu{sub 3}Ge{sub 4}O{sub 12}, which has the one-dimensional array of Cu{sub 3}O{sub 8} trimers formed of edge-sharing three CuO{sub 4} square planes. The exchange interactions between the Cu{sup 2+} (S = 1/2) spins have been determined by analyzing χ-T and C-T curves. By employing the isolated S = 1/2 Heisenberg trimer model above 70 K, the nearest-neighbor exchange couplings J{sub 1} and the second-neighbor one J{sub 2} in trimer have been evaluated to J{sub 1}/k{sub B} = 30 ± 20 K (antiferromagnetic) and J{sub 2}/k{sub B} = 340 ± 20 K. At low temperature region, two spins of the edge in the Cu{sub 3}O{sub 8} trimers form a nonmagnetic singlet by strong antiferromagnetic interaction J{sub 2}, and the spin left in the center of the Cu{sub 3}O{sub 8} trimer forms one-dimensional chains by the exchange interaction J{sub 3} between the trimers. By employing the S = 1/2 uniform Heisenberg chain model below 70 K, we have evaluated to J{sub 3}/k{sub B} = 18 ± 1 K. The mechanism of multiferroic behavior at T{sub c} = 2 K is discussed.
Authors:
 [1] ;  [2] ; ;  [3] ;  [3] ;  [2]
  1. Department of Physics, School of Science and Technology, Meiji University, Kawasaki 214-8571 (Japan)
  2. (Japan)
  3. Department of Physics, Nagoya University, Nagoya 464-8602 (Japan)
Publication Date:
OSTI Identifier:
22273826
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 17; Conference: 55. annual conference on magnetism and magnetic materials, Atlanta, GA (United States), 14-18 Nov 2010; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ANTIFERROMAGNETISM; COPPER IONS; COPPER OXIDES; DIELECTRIC PROPERTIES; EXCHANGE INTERACTIONS; GERMANATES; MAGNETIC SUSCEPTIBILITY; NMR SPECTRA; NUCLEAR MAGNETIC RESONANCE; ONE-DIMENSIONAL CALCULATIONS; POLYCRYSTALS; SODIUM 23; SODIUM COMPOUNDS; SPECIFIC HEAT; SPIN