Ground-state properties of a 2-dimensional Ising-system with competing interactions

Akai Kurbanovich Murtazaev, Рамазанов Магомедшейх Курбанович, М. К. Бадиев

Johannes Richter, S. Kobe

The ground-state properties and low-lying excitations of spin systems with competing interactions are studied for various finite two-dimensional S= 1 / 2 Heisenberg systems of 8 spins and corresponding Ising systems of up to 60 spins. The response of the spin systems on the conflict in the interactions is studied using numerical exact results. In the Ising model the competition of the interactions influences the ground state and the excitations essentially. Contrary to conventional Ising systems in disordered strongly frustrated Ising systems the low-energy density of states is smooth, the gap between the ground state and the first excitations vanishes. The low-lying excitations are characterised by a large portion of multiple spin excitations. Thermodynamic consequences are indicated. In the Heisenberg case the influence of the conflict in the interactions is less obvious, the character of the ground state and of the first excitation has similarities with that of conventional antiferromagnets, the spins have an enlarged number of possibilities to evade the conflict in the interactions.

秀稔 西森, Hidetoshi Nishimori

Wojciech Florek, Michał Antkowiak, G. Kamieniarz +1 more

We discuss three Ising ring systems with competing interactions which are analogs of quantum systems and we show that they exhibit similar properties.In particular, the archetypal system of three antiferromagnetically coupled spins s has two magnetically degenerated ground states with |M| s, when 0 J13 α 1 J12 J23.The same effect is observed in the centered rings and even-numbered systems with antiferromagnetic couplings between the second neighbors which are the geometrically frustrated.

Somayyeh Nemati, F. Khastehdel Fumani, S. Mahdavifar

Here we show that, although quantum fidelity can truly identify two quantum phase transitions of a one-dimensional spin-1/2 quantum Ising model with competing nearest and next-nearest neighbor interactions in a transverse magnetic field, it may not be a suitable approach for analyzing its ground-state phase diagram.

Norikiyo Uryû, Mitsuru Tanimura