2006/02/01 by Kazuo Hida · 4 citations
Physics and Astronomy · #Advanced Condensed Matter Physics #Antiferromagnetism #Density matrix renormalization group #Field (mathematics) #Magnetic field #Magnetization #Physics of Superconductivity and Magnetism #Quantum many-body systems #Quantum phase transition #Randomness #Spin (aerodynamics) #Zeeman effect #Zeeman energy #cond-mat.dis-nn #cond-mat.str-el
paper · pdf · doi:10.1143/jpsj.75.074709
published in Journal of the Physical Society of Japan 75(7), 074709 (Physical Society of Japan) · 5 pages, 8 figures
arxiv created 2006/02/01 · openalex publication_date 2006/06/29 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
The multiple reentrant quantum phase transitions in the S=1/2 antiferromagnetic Heisenberg chains with random bond alternation in the magnetic field are investigated by the density matrix renormalization group method combined with the interchain mean field approximation. It is assumed that the odd-th bond is antiferromagnetic with strength J and even-th bond can take the values \JS and \JW (\JS > J > \JW > 0) randomly with probability p and 1-p, respectively. The pure version (p=0 and p=1) of this model has a spin gap but exhibits a field induced antiferromagnetism in the presence of interchain coupling if Zeeman energy due to the magnetic field exceeds the spin gap. For 0 < p < 1, the antiferromagnetism is induced by randomness at small field region where the ground state is disordered due to the spin gap in the pure case. At the same time, this model exhibits randomness induced plateaus at several values of magnetization. The antiferromagnetism is destroyed on the plateaus. As a consequence, we find a series of reentrant quantum phase transitions between the transverse antiferromagnetic phases and disordered plateau phases with the increase of the magnetic field for moderate strength of interchain coupling. Above the main plateaus, the magnetization curve consists of a series of small plateaus and the jumps between them, It is also found that the antiferromagnetism is induced by infinitesimal interchain coupling at the jumps between the small plateaus. We conclude that this antiferromagnetism is supported by the mixing of low lying excited states by the staggered interchain mean field even though the spin correlation function is short ranged in the ground state of each chain.