Effect of high electric fields on the nematic to isotropic transition in a material exhibiting large negative dielectric anisotropy

Dhara, Surajit; Madhusudana, N.V.

Please use this identifier to cite or link to this item: http://hdl.handle.net/2289/2292

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DC Field	Value	Language
dc.contributor.author	Dhara, Surajit	-
dc.contributor.author	Madhusudana, N.V.	-
dc.date.accessioned	2007-04-25T10:59:20Z	-
dc.date.available	2007-04-25T10:59:20Z	-
dc.date.issued	2007-04-25	-
dc.identifier.citation	European Physical Journal E, 2007, Vol.22, p139-149	en
dc.identifier.issn	1292-8941	-
dc.identifier.issn	1292-895X (Online)	-
dc.identifier.uri	http://hdl.handle.net/2289/2292	-
dc.description	Restricted Access.	en
dc.description.abstract	We report the experimental high electric field phase diagram of a nematic liquid crystal which exhibits a large negative dielectric anisotropy. We measure simultaneously the birefringence ($\Delta n$) and the dielectric constant ($\epsilon_{\perp}$) at various applied fields as functions of the local temperature of an aligned sample. We also measure the higher harmonics of the electrical response of the medium. The following experimental results are noted: (i) enhancement of orientational order parameter S in the nematic phase due to both the Kerr effect and quenching of director fluctuations; (ii) enhancement in the paranematic to nematic transition temperature (TPN) with field; (iii) divergence of the order parameter susceptibility beyond the tricritical point as measured by third harmonic electrical signal; (iv) a small second harmonic electrical signal which also diverges near TPN, indicating the presence of polarised domains. Our measurements show that $\Delta T_{PN}(= T_{PN}(E)-T_{NI}(0))$ varies linearly with \|E\| whereas the Landau de Gennes theory predicts a dependence on E2. It is argued that the quenching of director fluctuations by the field makes the dominant contribution to all the observations, including the thermodynamics of the transition.	en
dc.format.extent	496491 bytes	-
dc.format.mimetype	application/pdf	-
dc.language.iso	en	en
dc.publisher	EDP Sciences	en
dc.relation.uri	http://dx.doi.org/10.1140/epje/e2007-00020-3	en
dc.rights	2007 EDP Sciences	en
dc.title	Effect of high electric fields on the nematic to isotropic transition in a material exhibiting large negative dielectric anisotropy	en
dc.type	Article	en
Appears in Collections:	Research Papers (SCM)

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