Finite-Field Ground State of theS=1 Antiferromagnetic–Ferromagnetic Bond-Alternating Chain

Abstract

We investigate the finite-field ground state of the S = 1 antiferromagnetic-ferromagnetic bond-alternating chain described by the Hamiltonian H = È ¨where J ≤ 0 and −∞ < D < ∞. We find that two kinds of magnetization plateaux at a half of the saturation magnetization, the 1 2 -plateaux, appear in the ground-state magnetization curve; one of them is of the Haldane type and the other is of the large-D-type. We determine the 1 2 -plateau phase diagram on the D versus J plane, applying the twistedboundary-condition level spectroscopy methods developed by Kitazawa and Nomura. We also calculate the ground-state magnetization curves and the magnetization phase diagrams by means of the density-matrix renormalization-group method.KEYWORDS: S = 1 antiferromagnetic-ferromagnetic bond-alternating chain, numerical methods, groundstate magnetization curve, -plateau phase diagram, magnetization phase diagram

Magnetoelastic and structural properties of azuriteCu3(CO3)2(Gibson1, Rule2, Wolter3 et al. 2010Phys. Rev. B13140View full textAdd to dashboardCite

“…Here, Cu 2+ ions form a triangular arrangement of spin S = 1/2 moments which are arranged as chains propagating along the crystallographic b-axis. The diamond chain model has been extensively studied [5][6][7][8][9] , with the distortion implied by three inequivalent exchange couplings, J 1 = J 2 = J 3 . This model affords a host of exotic phases and quantum phase transitions, including exotic dimer phases [7][8][9] or M = 1/3 fractionalisation 10,11 .…”

Finite-field ground state of an S=1 zigzag ladder

“…We are interested in how the obvious half plateau in the case of J rung ¼ J leg ¼ 0:0 is modified by the J rung -and J leg -terms, which represent, respectively, the chain-type and laddertype interactions. According to previous studies, in the simple ladder system where J rung ¼ 0:0 and J leg 40:0, the transition between the 'half plateau' phase and 'no plateau' phase takes place at J leg ¼ 0:6837 [2], and also in the nearest-neighboring ferromagnetic-antiferromagnetic bondalternating chain system where J leg ¼ 0:0 and J rung o0:0, it takes place at J rung ¼ À1:69 [1]. This 'half plateau'-'no plateau' transition is expected to occur also in the simple ladder system where J rung ¼ 0:0 and J leg o0:0, since this system is reduced to a two-independent-ferromagneticchain system in the limit of J leg !…”

“…It is noted that this plateau has the Haldane-type character; for more details the reader is referred to Ref. [1]. We are interested in how the obvious half plateau in the case of J rung ¼ J leg ¼ 0:0 is modified by the J rung -and J leg -terms, which represent, respectively, the chain-type and laddertype interactions.…”

“…The 'half plateau'-'no plateau' transition is the Berezinskii-Kosterlitz-Thouless transition [1,2]. Therefore, the critical value J ðcÞ rung of J rung (or J ðcÞ leg of J leg ) for a given value of J leg ðJ rung Þ can be estimated by employing the twisted-boundary-condition level spectroscopy (TBCLS) method developed by Nomura and Kitazawa [3].…”

“…In the regions A, B, and C, the reduced magnetization M=M s equal, respectively, to 0 (the zero plateau region),1 2 (the half plateau region), and 1. In the remaining region, M=M s increases continuously with increasing H.…”