Jitender Kumar, A. M. Awasthi
We have investigated the effects of dc-bias electric field on the dielectric response in single crystal potassium dihydrogen phosphate (KH2PO4). The bias-field dependence (up to 500V) of permittivity precisely marks the domain wall (DW) freezing temperature T_f (96K); changing its sign across the same, exactly where {\epsilon}' is field-insensitive. Characteristic DW freezing time suggests KWW stretched-exponential relaxation, obeying Vogel-Fulcher divergence with a field-invariant Kauzmann temperature T_K. A benchmark V_dc (150V) precisely splits the low- and high-field characters of the ferroelectric T_C, permittivity {\epsilon}'_{\omega}(123K), and the DW freezing activation energy E_a, which we attribute to a field-induced transition between the conventional 180-degrees-domains configuration and some highly-pinned antiferro-like organization of the dipoles. Over the temperature range hosting the DW response,field-cooled (poled) permittivity is higher than the zero-field-cooled (unpoled) case, being same elsewhere; neatly marking the dynamic regime of the domain-walls.
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http://arxiv.org/abs/1302.6078
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