Vector chiral and multipolar orders in the spin-12frustrated ferromagnetic chain in magnetic field

Abstract

We study the one-dimensional spin-1/2 Heisenberg chain with competing ferromagnetic nearestneighbor J1 and antiferromagnetic next-nearest-neighbor J2 exchange couplings in the presence of magnetic field. We use both numerical approaches (the density matrix renormalization group method and exact diagonalization) and effective field-theory approach, and obtain the ground-state phase diagram for wide parameter range of the coupling ratio J1/J2. The phase diagram is rich and has a variety of phases, including the vector chiral phase, the nematic phase, and other multipolar phases. In the vector chiral phase, which appears in relatively weak magnetic field, the ground state exhibits long-range order (LRO) of vector chirality which spontaneously breaks a parity symmetry. The nematic phase shows a quasi-LRO of antiferro-nematic spin correlation, and arises as a result of formation of two-magnon bound states in high magnetic fields. Similarly, the higher multipolar phases, such as triatic (p = 3) and quartic (p = 4) phases, are formed through binding of p magnons near the saturation fields, showing quasi-LRO of antiferro-multipolar spin correlations. The multipolar phases cross over to spin density wave phases as the magnetic field is decreased, before encountering a phase transition to the vector chiral phase at a lower field. The implications of our results to quasi-one-dimensional frustrated magnets (e.g., LiCuVO4) are discussed.

Orbital Arrangements and Magnetic Interactions in the Quasi-One-Dimensional Cuprates ACuMoO4(OH) (A = Na, K)

“…In fact, the exchange interactions of NaCuMoO4(OH) are estimated as J1 = -51 K and J2 = 36 K. 14 Note that the two interactions cause frustration in the spin chain, because J1 favors all the spins in the same direction whereas J2 tends to make every second spins antiparallel. This frustration can lead to a variety of magnetic phases such as spin nematic order, which is theoretically predicted to be a sort of spin liquid with an unusual spin order analogous to the nematic state in liquid crystals [16][17][18][19] but has not yet been observed in actual compounds 20 .…”

Phase diagram and continuous pair-unbinding transition of the bilinear-biquadraticS=1Heisenberg chain in a magnetic field

“…Starting from the dimerized phase, the magnetization of the finite systems grows regularly in steps of ∆M = 2/L, similar to the behavior in certain polarized S = 1/2 magnetic systems. [37][38][39][40][45][46][47] . This is rather natural.…”

Entanglement and level crossings in frustrated ferromagnetic rings

“…More recently, this model has attracted a fresh surge of theoretical attention [20,32,33,34,35,36,37,38,39], partly due to the appearance of materials whose spin physics is described by this model (see references in [20,32]). Most studies concentrate on finite magnetic fields or finite temperatures and on properties in the thermodynamic limit [20,28,29,30,31,32,33,34,35,36,37,38], or very near the transition point atβ = 4 [27,34,39,40].…”