New haldane gap system confirmed from high-field magnetization

doi:10.1016/0038-1098(90)90072-J

Solid State Communications

Volume 76, Issue 8, November 1990, Pages 999-1002

https://doi.org/10.1016/0038-1098(90)90072-J Get rights and content

Abstract

High-field magnetization measurements are performed on powder samples of the quasi - one - dimensional S = 1 antiferromagnets, NiC₂O₄2L (L=2-methylimidazole and 1, 2-dimethylimidazole) up to 36 Tesla at 1.7 K and 4.2 K. The observed magnetizations are very small below the definite critical field H_c near 13 Tesla and they increase abruptly above H_c, indicating a clear evidence for the existence of the non-magnetic ground state and magnetic excited state. The results are discussed in terms of the predicted Haldane gap for the one-dimensional antiferromagnet with integer spin. The compounds investigated are newly found to be the promising candidates for the Haldane gap system.

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Cited by (12)

Magnetostructural relationships for Ni(II) ions at octahedral sites in [Ni<inf>x</inf>Zn<inf>1-x</inf>(C<inf>2</inf>O<inf>4</inf>)(dmiz)<inf>2</inf>]: Computational study of zero-field splitting and using superposition model
2015, Polyhedron
Citation Excerpt :
An important class of the non-Kramers ions consists of the 3d4 and 3d6 (S = 2) ions [30–32] as well as 3d2 and 3d8 (S = 1) ions [33,17–19,34–36]. The pure Ni(C2O4)(dmiz)2 and mixed NixZn1−x(C2O4)(dmiz)2 derivatives, where dmiz is dimethyl imidazole, have aroused renewed interest [33,37–41] for possible testing of the Haldane conjecture [42] that predicted an energy gap between the ground state and the first excited state of one dimensional antiferromagnetic Heisenberg chains with integer spins. In view of significant importance in magnetism studies of Ni(II)-based Haldane gap systems [43–47] and our own work in this area [48–51], we have turned our attention to [NixZn1−x(C2O4)(dmiz)2].
Superposition model (SPM) analysis of the zero-field splitting parameters (ZFSPs), for short SPM/ZFSP, is utilized to investigate magnetostructural relationships in Ni(II)-based magnetic systems: the pure Ni(C₂O₄)(dmiz)₂ and mixed Ni_xZn₁₋_x(C₂O₄)(dmiz)₂ derivatives, where dmiz is 1,2-dimethylimidazole. The pure system is considered as an example of the S = 1 Heisenberg antiferromagnetic one-dimensional chain. The Haldane gap exhibited by such systems is the major motivation for their studies. SPM/ZFSP is based on knowledge of the model parameters, i.e. the intrinsic parameters – ${\bar{b}}_{k} (R_{0})$ , power law exponents – t_k, and the reference distance – R₀. As a first approximation we use the model parameter sets determined earlier for Ni(II) ions in the sixfold coordinated NiO₆ with axial symmetry. Matching of the SPM predicted ZFSPs with the experimental ones is carried out for several model parameter sets and various models of distortions around Ni(II) ions. The axial (D) and rhombic (E) ZFSPs obtained by high magnetic field/high-frequency EMR (HMF–EMR) for the derivatives Ni_xZn₁₋_x(C₂O₄)(dmiz)₂ for x = 0.09 and 0.07 are employed. Three approaches accounting for the local structural distortions with respect to the undistorted host are considered, namely, the angular distortions, the distortions of the ligand–metal bond lengths, and simultaneous distortions of the two types. This enables a thorough study of the magnetostructural relationships for the doped Ni(II) ions in Ni_xZn₁₋_x(C₂O₄)(dmiz)₂ and related crystals. Major finding is that SPM/ZFSP method is capable of yielding satisfactory matching of both the size and the signs of the predicted and experimental ZFSPs. Controversies concerning the very large D-values obtained by ab initio methods as compared with those usually observed in Ni(II) systems are discussed. Several inconsistencies concerning interpretation of experimental and theoretical data for Haldane gap systems are also clarified.
Haldane gap systems
2000, Coordination Chemistry Reviews
Haldane gap compounds with S=1 formulated as [Ni(AA)₂X]Y ((AA)₂=(diamines)₂, linear-tetramines, N₄-macrocycles; X=NO₂ and N₃; Y=ClO₄, BF₄ and PF₆) and (CH₃)₄N[Ni(NO₂)₃], and with S=2 formulated as [Mn(AA)₂Cl₃] (AA=bipy and phen) are described. They have one-dimensional structures with bridging ligands. The Haldane conjecture was proven by magnetic susceptibility and high-field magnetization measurements. The magnitudes of the Haldane gap with S=1 can be controlled by combination of the bridging ligands, in-plane ligands, and counteranions as follows: X, N₃>NO₂; AA, en≧tn>linear-tetramines>dmpn>Me₆[14]aneN₄≧[15]aneN₄; Y, ClO₄>PF₆. In spite of a similar structure to Haldane gap compounds, the [Ni([15]aneN₄)N₃]PF₆ and [Ni(en)₂(NO₂)]BF₄ species show spin-glass behavior, which is very novel in one-dimensional spin systems. The [Mn(bipy)Cl₃] is regarded as the first example of the Haldane gap system with S=2.
Nonmagnetic impurity effect on the Haldane gap system NiC<inf>2</inf>O<inf>4</inf>·2DMIz studied by high-field magnetization up to 40 T
1994, Physica B: Physics of Condensed Matter
Nonmagnetic impurity effect on the high-field magnetization of the Haldane system is systematically studied at 1.7 K in a magnetic field up to 40 T for the new compound Ni_1−xZn_xC₂O₄·2DMIz(0≤x≤)0.4), for the first time, in a wide concentration range. It was found that the magnetization curve is a sum of two distinct terms from the inner- and edge-spin contribution in finite chains. Bulk magnetization curves characteristic to the Haldane system still persist even in a Zn 20 at.% doped sample consistent with the theoretical result that the spin correlation length of the Haldane system is 5–6 atom lengths. Besides typical magnetization with finite energy gap, paramagnetic magnetization which comes from the edge-spins of S = 1 finite chains induced by nonmagnetic Zn²⁺ ion substitution appears for all samples in the lower field. The total saturation magnetization of the paramagnetic moments increases with Zn concentration with x, and its increase rate changes gradually at about x =0.05−0.1. It is shown that these behaviors are consistent with the recent theoretical prediction based on a quantum Monte Carlo method.
Single crystal susceptibility of the S = 1 one-dimensional Heisenberg antiferromagnet AgVP<inf>2</inf>S<inf>6</inf>
1994, Solid State Communications
A reliable single crystal susceptibility data is reported to reveal the ground state property of the S = 1 one-dimensional Heisenberg antiferromagnet AgVP₂S₆. The observed susceptibilities for the parallel and perpendicular direction to the chain axis fall down rapidly as the temperature is lowered down to about 50 K, revealing a non-magnetic singlet ground state nature of the system. The results are interpreted quantitatively within the framework of the Haldane prediction, giving the quantum gap of $E_{g} k_{B} ≈ 250 K$ which should be compared with 320 K from neutron scattering.
Synthesis, structure, and magnetic properties of 1D nickel coordination polymer Ni(en)(ox)·2H<inf>2</inf>O (en = ethylenediamine; ox = oxalate)
2009, Bulletin of the Korean Chemical Society
Direct determination of the single-ion anisotropy in a one-dimensional magnetic system by high-field EPR spectroscopy; synthesis, EPR, and X-ray structure of Ni(x)Zn(1-x)(C<inf>2</inf>O<inf>4</inf>)(dmiz)<inf>2</inf> [x = 0.07]
2000, Inorganic Chemistry

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New haldane gap system confirmed from high-field magnetization

Abstract

Phys. Lett.

Phys. Rev. Lett.

Phys. Rev.

Phys. Rev.

Phys. Rev. Lett.

Phys. Rev.

Europhys. Lett.