Cluster mean-field study of the Heisenberg model for CuInVO5

Abstract

Motivated by the experimental report of unusual low temperature magnetism in quasi onedimensional magnet CuInVO5, we present results of a cluster mean-field study on a spin-1/2 Heisenberg model with alternating ferromagnetic and antiferromagnetic nearest-neighbor coupling. We map out the ground state phase diagrams with varying model parameters, including the effect of an external magnetic field. An unexpected competition between different spin-spin correlations is uncovered. Multiple spin-flop transitions are identified with the help of component resolved correlation functions. For the material-specific choice of model parameters we discuss the temperature dependence of specific heat and magnetic susceptibility, and compare our results with the available experimental data. A detailed account of spin-spin correlations allows us to present a microscopic understanding of the low-temperature magnetic ordering in CuInVO5. Most notably, we identify the origin of an extra peak in the low temperature specific heat data of CuInVO5 reported by Hase et al. [1]. PACS numbers: 75.10.-b, 75.10.Pq, 75.40.Cx 1 2 3 4 J 2 J 2 J 1 J 3 FIG. 1. (Color online) A schematic picture of the coupled tetramer model. Each dot represents a spin-1/2 and the nearest-neighbor couplings are indicated by double (J1), solid (J2) and dotted (J3) lines.

Quantum Ising model on the frustrated square lattice

“…In this case, the CMF theory can provide a reputable framework. In fact, CMF approaches have been adopted in several recent studies in condensed matter physics and statistical mechanics [5,6,[18][19][20][21][22]. The technique consists in dividing the lattice in N cl equivalent clusters with n s sites each.…”

“…In this technique, the intracluster interactions are incorporated exactly and the couplings between clusters are approximated by mean fields. The CMF framework has been considered in many recent investigations of spin models [5,6,[18][19][20][21][22] in which frustration and quantum fluctuations are often present. In particular, this method was applied to the Ising [5] and Heisenberg [22] versions of the J 1 -J 2 model, providing a description for the nature of the magnetic phase boundaries in agreement with stateof-art numerical and analytical calculations.…”

Multiple phase transitions and high-field quadrupolar order in a model for β−TeVO4

“…We use the CMF approach to understand the nature of magnetic ordering in this model. The CMF has proven extremely useful for investigating spin models possessing magnetic frustrations of geometrical or Kitaev nature [19][20][21][22][23]. The key idea of the method is to treat all interaction links located within the cluster exactly, and to make use of the conventional mean field decoupling, S i • S j ≈ S i • S j + S i • S j − S i • S j , for interaction links connecting the cluster and the environment.…”

“…( 2), and the trace is over all states of the H c with converged values of the mean field parameters. Further details of the method and its extensions are available in some recent papers [19][20][21][22][23].…”

Magnetism in spin crossover systems: Short-range order and effects beyond the Heisenberg model

“…However, the Heisenberg term contains spin fluctuations, which are neglected within the standard MF consideration. To go beyond MF we use its cluster generalization, the self-consistent CMF, which has been applied to various quantum spin models [46][47][48][49][50][51][52][53][54][55][56]. The approach captures short-range effects, which will be discussed in the next section, and allows treating HS and LS terms equally within a cluster.…”