Magnetic fluids in an external field
Institute for Semiconductor Physics, University of Linz,
Altenbergerstrasse 69, 4040 Linz, Austria
2 Institute for Theoretical Physics, University of Linz, Altenbergerstrasse 69, 4040 Linz, Austria
Published online: 15 March 1999
Within mean field approximation we investigate the phase diagrams of magnetic fluids in presence of a magnetic field. In a finite field the magnetic phase transition is absent, but instead a line of first order liquid-liquid transitions ending in a critical point occurs for a magnetic interaction, which is sufficiently strong. Varying the magnetic field these critical points extend from the tricritical point at H=0 to a critical endpoint. For a fluid with Ising spins we calculate the critical lines and several tricritical exponents analytically. For Heisenberg fluids we obtain the phase diagrams from a numerical solution of the mean field equations of state.
PACS: 64.60.Fr – Equilibrium properties near critical points, critical exponents / 64.60.Kw – Multicritical points / 75.50.Mm – Magnetic liquids
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 1999