Magnetic property of vanadium-molybdenum oxides

Shiozaki, Ikuyo

doi:10.1016/s0304-8853(97)00977-3

Cited by 10 publications

(12 citation statements)

References 4 publications

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“…I were derived. First one notices that J ⊥ is at least four orders of magnitude smaller than the in-plane coupling constants, pointing out that VOMoO 4 is a 2D system and not a one-dimensional one as claimed by Shiozaki and coworkers 11,12 . Second, it should be observed that the value of J 1 + J 2 ranges between 132 and 170 K, in good agreement with the value Θ = J 1 + J 2 ≃ 155 K derived experimentally for the Curie-Weiss temperature.…”

Section: A Electronic Structure and Superexchange Couplingsmentioning

confidence: 88%

“…The only difference is that in Li 2 VOSiO 4 a plane of Li + ions is present between the SiVO 5 layers. VOMoO 4 has been recently investigated by Shiozaki and coworkers 11 , which, however, have considered it as a protoype of a weakly one-dimensional antiferromagnet 12 instead of a 2DFQHAF, as it will be shown in the following. The interest for VOMoO 4 stems from the fact that although the structure is very similar to the one of Li 2 VOSiO 4 the exchange couplings are more than an order of magnitude larger.…”

Section: Introductionmentioning

confidence: 99%

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Frustration-driven structural distortion inVOMoO4

et al. 2002

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Nuclear magnetic resonance (NMR), electron paramagnetic resonance (EPR), magnetization measurements and electronic structure calculations in VOMoO4 are presented. It is found that VOMoO4 is a frustrated two-dimensional antiferromagnet on a square lattice with competing exchange interactions along the side (J1) and the diagonal (J2) of the square. From magnetization measurements J1 + J2 is estimated around 155 K, in satisfactory agreement with the values derived from electronic structure calculations. Around 100 K a structural distortion, possibly driven by the frustration, is evidenced. This distortion induces significant modifications in the NMR and EPR spectra which can be accounted for by valence fluctuations. The analysis of the spectra suggests that the size of the domains where the lattice is distorted progressively grows on cooling as the temperature approaches the transition to the magnetic ground state at Tc ≃ 42 K.

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Section: A Electronic Structure and Superexchange Couplingsmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Frustration-driven structural distortion inVOMoO4

et al. 2002

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“…Initially, VOMoO 4 was considered as a weak one-dimensional antiferromagnet. [11][12][13] However, recent band-structure calculations by Carretta et al 14 have shown that this system is essentially two dimensional ͑2D͒, with extremely weak interplanar coupling. The crystal structure of VOMoO 4 , shown in Fig.…”

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confidence: 99%

Magnetic order and lattice anomalies in theJ1−J2model systemVOMo

et al. 2005

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High-resolution x-ray and neutron powder-diffraction measurements were performed on polycrystalline VOMoO 4 . Below Ӎ40 K the system orders in a simple Néel antiferromagnetic state ͑propagation vector k ជ =0͒, indicating a dominant role of the nearest-neighbor interactions. The order is three dimensional but the reduced saturated magnetic moment m of 0.41 ͑1͒ B / V 4+ at 2 K indicates strongly two-dimensional character and enhanced quantum fluctuations. On cooling, there is no evidence of a reduction of the crystal symmetry. However, neutron diffraction indicates an anomalous evolution of the lattice parameters, which can be related to the onset of magnetic correlations.Frustrated magnets based on transition metals have become subjects of many theoretical and experimental studies in the past years: 1,2 a variety of exotic quantum effects are expected when competitive interactions lead a system into a frustrated state, where it is impossible to satisfy all the pair interactions simultaneously. One of the most studied model systems is the spin-1 / 2 Heisenberg antiferromagnet on a square lattice with competing nearest-͑J 1 ͒ and next-nearest-͑J 2 ͒ neighbor antiferromagnetic interactions. In two dimensions, the zero-point quantum fluctuations ͑enhanced by a low spin value͒, combined with the frustration, are strong enough to destroy the long range ordering in the system even at zero temperature. The two limiting cases of this model are relatively simple and well understood: when J 1 ӷ J 2 , the system orders into a simple Néel state, whereas when J 1 Ӷ J 2 the problem can be treated in terms of two decoupled interpenetrating Néel lattices. In the mean-field limit, all the relative orientations of these two sublattices have the same energy, but the order-by-disorder mechanism 3 lowers the energy of the collinear states. The intermediate situation is still a matter of debate; in particular, different predictions exist concerning the magnetic and nonmagnetic ground states in the vicinity of the fully frustrated point ͑J 1 Ӎ 2 ϫ J 2 ͒ ͑Ref. 4͒.Recently, several new vanadium-based compounds have provided experimental realizations of the J 1 -J 2 model, and are currently receiving significant attention by the scientific community. The first widely studied prototype of this family was Li 2 VOSiO 4 ͑Ref. 5͒. At low temperature, this material was found to order in the collinear magnetic state. 6-8 The staggered magnetization from neutron scattering was found to be 0.63 B , in excellent agreement with J 2 / J 1 Ӎ 12, as obtained from band-structure calculations and bulk properties measurements. 9 Another window into this phase diagram is provided by the closely related system VOMoO 4 ͑Ref. 10͒. Initially, VOMoO 4 was considered as a weak one-dimensional antiferromagnet. 11-13 However, recent band-structure calculations by Carretta et al. 14 have shown that this system is essentially two dimensional ͑2D͒, with extremely weak interplanar coupling. The crystal structure of VOMoO 4 , shown in Fig. 1, presents many similarities w...

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“…The strength of magnetic interactions and the ordering type of the ions magnetic moments in [8,9] that in (VO)MoO 4 compounds the parameter c reduces at cooling that is accompanied by a removal of basal O b ions from the VO-VO chain.…”

Section: Characterization Of Magnetic Interactions and The Origin Of mentioning

confidence: 99%

The study of nearest- and next-nearest-neighbour magnetic interactions in seven tetragonal compounds of V(IV) containing linear chains and square lattices

Волкова¹,

Polyshchuk²

2006

J. Phys.: Condens. Matter

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A new crystal chemical method was used to calculate the sign and strength not only of the nearest-neighbor (NN) interactions, but also of the next-nearestneighbor (NNN) ones in tetragonal compounds Zn 2 (VO)(PO 4 ) 2 (I), (VO)(H 2 PO 4 ) 2 (II), (VO)SiP 2 O 8 (III), (VO)SO 4 (IV), (VO)MoO 4 (V), Li 2 (VO)SiO 4 (VI) and Li 2 (VO)GeO 4 (VII) with similar sublattices of V 4+ ions on the basis of the room-temperature structural data. The reason for difference between respective magnetic interactions characteristics of these compounds was established. It is shown that the characteristic feature of these compounds is a strong dependence of the strength of magnetic interactions and the magnetic moments ordering type on slight displacements of XO 4 (X = P, Mo, Si or Ge) groups even without change of the crystal symmetry. In addition to extensively studied square lattice, other specific geometrical configurations of V 4+ were discovered. These configurations can result in frustration of magnetic interactions, namely linear chains along the c-axis with competing nearest-and next-to-nearest-neighbor interactions; rectangular (in I) and triangular (in II-VII) lattices with non-equivalent nearest-to-neighbor interactions, which can be also considered as n-leg ladders; one extra square lattice in the ab-plane with longer range interactions. It was concluded that virtually all magnetic interactions in these compounds were frustrated.Our estimation of magnetic interactions shows that in all compounds I-VII the antiferromagnetic nearest-neighbor J 1 interactions in linear chains along the c-axis are at least six times stronger than other J 2 -J 8 interactions. However, these interactions compete with weaker J 7 ( s s J J 1 7 ≅ 1/6) AF next-13 nearest-neighbor interactions in a chain. For nearest-and next-nearest-neighbor interactions in antiferromagnetic chain, instability against spontaneous dimerization for NN c NNN NNN J J J 6 1 ≅ > wasfound [21]. One can assume that, in addition to the competition between J 1 and J 7 interactions in chains along the c-axis, a competition between other interactions in these systems takes place. Let us consider the competition between interactions on the basis of representation of the structure of these compounds as crossed diagonal planes of a unit cell. As shown above, these planes comprise rectangular lattices with two non-equivalent nearest-neighbor bonds (J 1 ≠J 2 ) in Zn 2 (VO)(PO 4 ) 2 and distorted triangular lattices with three non-equivalent nearest-neighbor bonds (J 1 ≠J 2 ≠J 3 ) in other compounds (figure 2). Determination of competition between interactions J 1 , J 2 and J 3 in rectangulars and triangles, which are basic elements of these lattices, is of great difficulty because of non-equivalence of strengths of interactions and superposition of competitions by additional next-nearest-neighbor interactions. Based only on the signs of interactions, which we calculated, the rectangles with FM J 3 interactions (along diagonals) and AF J 1 and FM J 2 interactions (along the sides) (J ...

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Magnetic property of vanadium-molybdenum oxides

Cited by 10 publications

References 4 publications

Frustration-driven structural distortion inVOMoO4

Frustration-driven structural distortion inVOMoO4

Magnetic order and lattice anomalies in theJ1−J2model systemVOMo

The study of nearest- and next-nearest-neighbour magnetic interactions in seven tetragonal compounds of V(IV) containing linear chains and square lattices

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