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Full-Text Articles in Physics

Discotic Micellar Nematic And Lamellar Phases Under Shear-Flow, J. T. Mang, Satyendra Kumar, B. Hammouda Dec 1994

Discotic Micellar Nematic And Lamellar Phases Under Shear-Flow, J. T. Mang, Satyendra Kumar, B. Hammouda

Physics Publications

Small-angle neutron scattering was employed to study the effect of shear flow on the nematic (N) and lamellar (L(alpha)) phases in aqueous solutions of cesium perfluoro-octanoate. Shear rates as high as similar to 4000 s(-1) were used. The N phase was found to align with the director in the direction of the gradient velocity. The L, phase oriented with lamellae parallel to the shear plane. This change in equilibrium orientation is attributed, primarily, to changes in the value of the Ericksen viscosity parameter at. Subtle shear-rate-dependent director reorientations were also observed in the proximity of the N-to-L(alpha ...


Random-Field Critical And Spin-Flop Behavior Of The Anisotropic Heisenberg Antiferromagnet Fe0.9mg0.1br2 In Axial Magnetic Fields, Christian Binek Feb 1994

Random-Field Critical And Spin-Flop Behavior Of The Anisotropic Heisenberg Antiferromagnet Fe0.9mg0.1br2 In Axial Magnetic Fields, Christian Binek

Christian Binek Publications

Faraday optical measurements on the dilute hexagonal antiferromagnet Fe0.85Mg0.15Br2 in an external axial field reveal a spin-flop phase line ending at a multicritical point (Tm=8.1 K, Hm=1050 kA m-1) and crossover from random-exchange to random-field Ising criticality with an exponent Phi =1.40+or-0.04 in the vicinity of TN=11.1 K. Cusp-like behaviour of the specific heat at TN is discussed in view of recent Monte Carlo results.