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Title: Magnetic and magnetodielectric coupling anomalies in the Haldane spin-chain system Nd{sub 2}BaNiO{sub 5}

We report the magnetic, heat-capacity, dielectric and magnetodielectric (MDE) behaviour of a Haldane spin-chain compound containing light rare-earth ion, Nd{sub 2}BaNiO{sub 5}, in detail, as a function of temperature (T) and magnetic field (H) down to 2 K. In addition to the well-known long range antiferromagnetic order setting in at (T{sub N} = ) 48 K as indicated in dc magnetization (M), we have observed another magnetic transition near 10 K; this transition appears to be of a glassy-type which vanishes with a marginal application of external magnetic field (even H = 100 Oe). There are corresponding anomalies in dielectric constant (ε′) as well with variation of T. The isothermal M(H) curves at 2 and 5 K reveal the existence of a magnetic-field induced transition around 90 kOe; the isothermal ε′(H) also tracks such a metamagnetic transition. These results illustrate the MDE coupling in this compound. Additionally, we observe a strong frequency dependence of a step in ε′(T) with this feature appearing around 25-30 K for the lowest frequency of 1 kHz, far below T{sub N}. This is attributed to interplay between crystal-field effect and exchange interaction between Nd and Ni, which establishes the sensitivity of dielectric measurements to detectmore » such effects. Interestingly enough, the observed dispersions of the ε′(T) curves is essentially H-independent in the entire T-range of measurement, despite the existence of MDE coupling, which is in sharp contrast with other heavy rare-earth members in this series.« less
Authors:
;  [1] ;  [2] ;  [3]
  1. Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai-400005 (India)
  2. Indian Institute of Technology Bhubaneswar, Bhubaneswar, Odisha- 171013 (India)
  3. UGC-DAE Consortium for Scientific Research, Indore Centre, Khandwa Road, Indore - 452001 (India)
Publication Date:
OSTI Identifier:
22454479
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Advances; Journal Volume: 5; Journal Issue: 3; Other Information: (c) 2015 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ANTIFERROMAGNETISM; COUPLING; CRYSTAL FIELD; DIAGRAMS; DIELECTRIC MATERIALS; EXCHANGE INTERACTIONS; FREQUENCY DEPENDENCE; IONS; KHZ RANGE; MAGNETIC FIELDS; MAGNETIZATION; PERMITTIVITY; RARE EARTHS; SENSITIVITY; SPECIFIC HEAT; SPIN; TEMPERATURE DEPENDENCE