Phase transitions in layered spin systems

Andrzej Zagorski, Andrzej Sukiennicki

Lian Zheng, Richard J. Radtke, S. Das Sarma

We study intersubband spin density collective modes in double-layer quantum Hall systems at $\ensuremath{\nu}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}2$ within the time-dependent Hartree-Fock approximation. We find that these intersubband spin density excitations may soften under experimentally accessible conditions, signaling a phase transition to a new quantum Hall state with interlayer inplane antiferromagnetic spin correlations. We show that this novel canted antiferromagnetic phase is energetically stable and that the phase transition is continuous.

Johannes Richter, S E Kreuger, DAMIAN J. J. FARNELL +1 more

Muhammed Derviş Baran, Ümüt Temizer

The dynamic magnetic behavior of the mixed-spin Ising trilayer structure, composed of a ferrimagnetically A-layer with spin-1, B-layer with spin-3/2 and a C-layer with spin-2, is investigated by using the mean-field approximation with Glauber-type stochastic dynamics. The dynamic equations describing the time-dependencies of the system are derived from the Master equation and the Glauber transition rates. The time variations of the average magnetizations and the behaviors of the dynamic magnetizations as a function of the temperature and magnetic field are investigated to find the phases and phase transition points, respectively. The dynamic phase diagrams are presented on different planes, and they exhibit several ordered phases and coexistence phase regions besides the disordered phase. Our model highlights first- and second-order phase transitions as well as the emergence of tricritical point, triple point, quadruple point, critical end point, double critical end point and multicritical point.

van Kah Ton Leeuwen

Alain H. Billoire