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Title: Nonlinear alternating current conduction in polycrystalline manganites

The real part of ac conductance Σ(T, f) of yttrium-doped mixed-valent polycrystalline manganite systems La{sub 1−x−y}Y{sub y}Ca{sub x}MnO{sub 3} with x = 0.33 and 0.05 and y = 0.07 and iron doped LaMn{sub 1−x}Fe{sub x}O{sub 3} with x = 0.15 is measured as a function of frequency f by varying zero-frequency Ohmic conductance Σ{sub 0} by T. The former shows a metal-insulator transition, whereas the latter exhibits insulating character throughout the measured temperature range. At a fixed temperature T, Σ(T, f) remains almost constant to the value Σ{sub 0} up to a certain frequency, known as the onset frequency f{sub c} and increases from Σ{sub 0} as frequency is increased from f{sub c}. Scaled appropriately, the data for Σ(T, f) at different T fall on the same universal curve, indicating the existence of a general scaling formalism for the ac conductance. f{sub c} scales with Σ{sub 0} as f{sub c}∼Σ{sub 0}{sup x{sub f}}, where x{sub f} is the nonlinearity exponent characterising the onset. With the help of data for ac conduction, it is shown that x{sub f} is very much phase sensitive and can be used to characterize the different phases in a manganite system originated due to change in temperature or disorder. Scaling theories andmore » existing theoretical models are used to analyze the results of ac conduction and the nonlinearity exponent x{sub f}.« less
Authors:
 [1] ;  [2] ;  [3] ; ;  [4]
  1. Department of Electronics, Vidyasagar University, Midnapore, West Bengal 721 102 (India)
  2. Department of Physics, Scottish Church College, 1 and 3, Urquhart Square, Kolkata 700 006 (India)
  3. Department of Physics, University of Calcutta, 92, A P C Road, Kolkata 700 009 (India)
  4. Department of Solid State Physics, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032 (India)
Publication Date:
OSTI Identifier:
22303580
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 24; 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; ALTERNATING CURRENT; CALCIUM COMPOUNDS; DOPED MATERIALS; ELECTRIC CONDUCTIVITY; FERRITES; FREQUENCY DEPENDENCE; IRON ADDITIONS; LANTHANUM COMPOUNDS; MANGANATES; MANGANESE COMPOUNDS; POLYCRYSTALS; SCALING; YTTRIUM ADDITIONS; YTTRIUM COMPOUNDS