All-boron planar ferromagnetic structures: from cluster to monolayer

Ferromagnetism in all-boron planar clusters is revealed based on high-throughout first-principles calculations. Magnetic boron clusters induced from $p$ electrons have been confirmed with large spins e.g. S=3 in a B34...

Exotic orbits due to spin–spin coupling around Kerr black holes

We report exotic orbital phenomena of spinning test particles orbiting around a Kerr black hole, i.e. some orbits of spinning particles are asymmetrical about the equatorial plane. When a nonspinning test particle orbits around a Kerr black hole in a strong field region, due to relativistic orbital precessions, the pattern of trajectories is symmetrical about the equatorial plane of the Kerr black hole. However, the patterns of the spinning particles’ orbit are no longer symmetrical about the equatorial plane for some orbital configurations and large spins. We argue that these asymmetrical patterns come from the spin–spin interactions between spinning particles and Kerr black holes, because the directions of spin–spin forces can be arbitrary, and distribute asymmetrically about the equatorial plane.

QUANTUM-CLASSICAL PHASE TRANSITION OF THE ESCAPE RATE OF TWO-SUBLATTICE ANTIFERROMAGNETIC LARGE SPINS

The Hamiltonian of a two-sublattice antiferromagnetic spins, with single (hard-axis) and double ion anisotropies described by [Formula: see text] is investigated using the method of effective potential. The problem is mapped to a single particle quantum-mechanical Hamiltonian in terms of the relative coordinate and reduced mass. We study the quantum-classical phase transition of the escape rate of this model. We show that the first-order phase transition for this model sets in at the critical value Jc = (Kc+Jz, c)/2 while for the anisotropic Heisenberg coupling [Formula: see text] we obtain Jc = (2Kc-Jz, c)/3. The phase diagrams of the transition are also studied.

QUANTUM FLUCTUATIONS OF ROTATING STRINGS IN AdS5 × S5

We discuss quantum fluctuations of a class of rotating strings in AdS 5 × S 5. In particular, we develop a systematic method to compute the one-loop sigma-model effective actions in closed forms as expansions for large spins. As examples, we explicitly evaluate the leading terms for the constant radii strings in the SO (6) sector with two equal spins, the SU (2) sector, and the SL (2) sector. We also obtain the leading quantum corrections to the space–time energy for these sectors.