Liquid-crystal monolayers in high magnetic fields: a second-harmonic generation study

W e present the first experim ental results on the m olecular o rientation of LC m onolayers in high m agnetic fields. The influence of the external m agnetic field on the in-plane m olecular o rientation of 4-n-octyl-4'-cyanobiphenyl (8CB) molecules on rubbed polym er surfaces is studied w ith the use of second-harm onic generation. It is found th a t the orien tatio n of the LC m olecules is fixed w ith respect to the rubbing axis u p to m agnetic fields of 20 T. These results are in-line w ith the previously proposed m odel for surface-induced LC alignm ent based on a LC bulk interacting w ith a fixed interfacial LC m onolayer. It can also be concluded th a t hardly any collective behaviour of the LC m olecules, constituting the first m onolayer, is present.