Quantum magnetism and criticality

Yasuhiro Tada

This work studies quantum criticality of the magnetic catalysis which is a magnetic field induced phase transition in a Dirac semimetal. The critical exponents are calculated based on a scaling ansatz.

Hirohito Kiwata

It has been shown that there exists an additional magnetic phase transition of the magnetization curve for the S=1 SU(3) antiferromagnetic spin chain at zero temperature. As a the magnetic field decreases from the saturation field, there is a phase change at a critical field h c , where the magnetization curve versus the magnetic field has a cusp. The critical field is a boundary between two states, one of which contains the particles with the spin +1 and 0 and the other with the spin +1, 0 and -1. In this paper we estimate the critical field h c of the phase transition by examining the stability of these states.

Paul C. Canfield

B. Barbara, Yosef Imry, G. A. Sawatzky +1 more

Vimalesh Kumar Vimal, V. Subrahmanyam

We investigate the dynamics of a spin chain with Kitaev-type interaction in a transverse magnetic field, for both a constant field and a periodically kicked field. We investigate analytically the revivals in the dynamical behavior of the magnetization, and measures of local quantum correlations, the concurrence measure of the entanglement, and the quantum discord. The magnetization revivals are seen even for larger chain lengths, with reduced revival peaks, both near and away from the critical point at zero magnetic field. The quantum entanglement and correlation measures, contrary to the expected behavior, exhibit reduced quantum correlations in the critical region, compared to the region away from the critical point. The concurrence is larger than the quantum discord away from the critical region. The pair entanglement is near zero for all times in the critical region, though the quantum discord is nonzero, capturing the underlying diagonal correlations. The kicked magnetic field dynamics shows similar evolution for the magnetization and quantum correlations. For special values of the kicking period, the concurrence shows alternates between zero and nonzero values for successive kicks in the noncritical region.