Optical investigation of the temperature and order parameter dependences of interfacial roughening in a random-field system

The pinning and roughening of structural domain walls by random fields was studied in Tb(As0.15V0.85)O-4 by measuring the intensities of laser light B ragg-scattered from orthorhombic twin interfaces as the sample was repeated ly warmed and cooled through its structural phase transition. Determination of the temperature-dependent roughness with submicron precision as well as its correlation length has shown that the domain walls are rougher than in pure TbVO4, has allowed the identification of a metastable microdomain sta te upon sample cooling, and has permitted investigation of the scaling of t he roughness with order parameter. [S0163-1829(99)09013-X].