Spin-singlet trimer state induced by competing orbital order in triangular-lattice BaV<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mn>10</mml:mn></mml:msub></mml:math>O<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mn>15</mml:mn></mml:msub></mml:math>

Shimizu, Yasuhiro; Matsudaira, Keniichiro; Itoh, Masatoshi; Kajita, T.; Katsufuji, T.

doi:10.1103/physrevb.84.064421

Cited by 15 publications

(8 citation statements)

References 28 publications

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“…The method can be applied in the spin-singlet state. 27 For 51 V nuclear spins, I = 7/2, electric quadrupole interactions under the electric field gradient (EFG) split NMR spectra with an interval frequency δν. δν consists of the on-site d orbital and the outer ligand terms: δν = δν on + δν out , where the components of δν on are expressed by…”

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confidence: 99%

Orbital reformation with vanadium trimerization ind2triangular lattice LiVO2revealed by51V NMR

et al. 2013

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LiVO 2 is a model system of the valence bond solid (VBS) in 3d 2 triangular lattice. The origin of the VBS formation has remained controversial. We investigate the microscopic mechanism by elucidating the d orbital character via on-site 51 V NMR measurements in a single crystal up to 550 K across a structural transition temperature T c . The Knight shift, K, and nuclear quadrupole frequency, δν, show that the 3d orbital with local trigonal symmetry are reconstructed into a d yz d zx orbital order below T c . Together with the NMR spectra with three-fold rotational symmetry, we confirm a vanadium trimerization with d-d σ bonds. The Knight shift extracts the large Van-Vleck orbital susceptibility, χ VV = 3.6 × 10 −4 , in a paramagnetic state above T c , which is comparable to the spin susceptibility. The results suggest that orbitally induced Peierls transition in the proximity of the frustrated itinerant state is the dominant driving force of the trimerization transition. PACS numbers: 71.30.+h, 75.40.Gb Valence bond ordering in two-and three-dimensional systems is a manifestation of geometrical frustration.1 Across Mott transition, a valence bond solid (VBS) phase resides nearby unconventional metal 2,3 and superconducting phases 3 in triangular lattice systems. The VBS transition can accompany by d orbital orders with versatile textures, depending on lattice geometry and band filling. 4-9 However, d orbital orders governed by frustrated intersite interactions are not apparent from lattice distortions and need to be detected by microscopic probes. Here we show a tool for detailed characterization of d 2 orbital ordering in a model material LiVO 2 with the triangular lattice.ABX 2 (A:alkali metal; B: transition metal; X: chalcogen ion) with an ordered lock-type structure is a prototype of triangular-lattice antiferromagnet. 9 For Ti 3+ and V 3+ , t 2g orbital degrees of freedom play crucial roles in determining magnetic ground states. Among ABX 2 , LiVO 2 has been extensively investigated as a candidate of VBS.10-14 The crystal structure is comprised of the triangular lattice of V 3+ (3d 2 ) ions in a rhombohedral R3c structure [ Fig. 1(a)]. A trigonal elongation of VO 6 along the c axis splits the t 2g sublevel into a lower a 1g singlet and an upper e15 Calculated orbital occupations are almost equivalent in the a 1g and e ′ g orbitals due to the small trigonal field of 25 meV compared to the bandwidth.15 Below a first-order structural transition temperature T c ∼ 450-500 K, a superlattice Fig. 1(a)] appears in x-ray and electron diffraction measurements.11-14 Recent pair distribution function analyses of synchrotron data propose lowersymmetry lattice distortions depending on the layers. 16 Although the way of displacements of vanadium ions is compatible to trimerization, 12,13,16 the orbital character has not been accessible by the diffraction measurements due to Li deficiency and crystal twinning. Thus, the origin of the spin-singlet state in LiVO 2 remains controversial and to be elucidated via direct obse...

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Orbital reformation with vanadium trimerization ind2triangular lattice LiVO2revealed by51V NMR

et al. 2013

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“…Namely, only I (0k0) /I (050) can be obtained in the calculation. On the other hand, the absolute intensities at different Q positions are difficult to compare experimentally because of the different scattering angles, 29 30 The orbital occupancies can also be discussed in the LDA calculation from the splitting of the density of the state (DOS). For example, quite large splittings of DOS are observed for the d xy and d yz states in the V2B site, and the lower states of them are occupied, whereas the higher states are unoccupied [ Fig.…”

Section: Methodsmentioning

confidence: 99%

Orbital states of V trimers in BaV10O15detected by resonant x-ray scattering

et al. 2012

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BaV 10 O 15 shows a structural phase transition associated with the trimerization of V ions at T s = 123 K. We investigated the orbital states of V trimers using the technique of resonant x-ray scattering (RXS) near the V K-edge absorption energy. The ratio of the intensity between the pre-edge structure (1s to 3d transition) and the main-edge structure (1s to 4p transition) strongly depends on the reciprocal Q position of the scattering. We found that the Q position dependence is consistent with the model of orbital ordering proposed by Pen et al.,

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“…9,10 In the insulating phase of BaV 10 O 15 , V 2+ and V 3+ charge ordering is characterized by localized t 2g orbitals of d 3 and d 2 site with ferromagnetic coupling between them in the trimer, [13][14][15] which is the case contrary to the spin singlet trimers in LiV 3+ O 2 . The Raman studies previously reported on the presence of randomly oriented trimers with decreasing temperature below 220 K. 16 In addition, the splitting of V nuclear magnetic resonance (NMR) spectra indicated the symmetry lowering and no structural transition below 220 K. 17 Further from the NMR and X-ray diffraction measurements, the phase diagram of BaV 10 O 15 has shown the high-temperature phase (300 K -220 K), the intermediate-temperature phase (220 K -130 K), and the low-temperature phase (below 130 K). 17 Although the structural, transport, and optical properties are studied for BaV 10 O 15 including the electronic properties only at 75 and 300 K, [11][12][13] the electronic properties across the intermediate-temperature phase have not yet been studied.…”

Section: Introductionmentioning

confidence: 97%

“…The Raman studies previously reported on the presence of randomly oriented trimers with decreasing temperature below 220 K. 16 In addition, the splitting of V nuclear magnetic resonance (NMR) spectra indicated the symmetry lowering and no structural transition below 220 K. 17 Further from the NMR and X-ray diffraction measurements, the phase diagram of BaV 10 O 15 has shown the high-temperature phase (300 K -220 K), the intermediate-temperature phase (220 K -130 K), and the low-temperature phase (below 130 K). 17 Although the structural, transport, and optical properties are studied for BaV 10 O 15 including the electronic properties only at 75 and 300 K, [11][12][13] the electronic properties across the intermediate-temperature phase have not yet been studied. In view of the complicated transport and optical properties across the intermediate-temperature phase, 11,16,17 the present work is dedicated to study the electronic properties at 180, 245, and 300 K including the insulating phase (70 K).…”

Section: Introductionmentioning

confidence: 97%

“…17 Although the structural, transport, and optical properties are studied for BaV 10 O 15 including the electronic properties only at 75 and 300 K, [11][12][13] the electronic properties across the intermediate-temperature phase have not yet been studied. In view of the complicated transport and optical properties across the intermediate-temperature phase, 11,16,17 the present work is dedicated to study the electronic properties at 180, 245, and 300 K including the insulating phase (70 K). A band gap of 0.3 eV at the low-temperature insulating phase was reported from the optical studies.…”

Section: Introductionmentioning

confidence: 99%

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Temperature-dependent valence state within the metallic phase of BaV10O15 probed by hard x-ray photoelectron spectroscopy

et al. 2019

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We have studied electronic properties of BaV10O15 in the intermediate-temperature phase as well as in the high-temperature metallic phase by using hard x-ray photoemission spectroscopy (HAXPES). The V 2p HAXPES show a shift in the high temperature phase between 300 K and 245 K which is similar to the shift of spectral weight near the Fermi edge. The binding energy of the O 1s HAXPES peak does not change except a slight shift of the lower binding energy edge in the opposite direction between 300 K and 180 K across the transition to the intermediate-temperature phase. This behavior is in sharp contrast to the transition to the low-temperature insulating phase where V 2p and O 1s HAXPES show dramatic shifts in the same direction. This indicates that the charge-orbital change in the intermediate-temperature phase is driven by the correlated V 3d electrons and is electronic. The V 2.5+-V 2.5+ bond ordering is related to the metallic contribution and gradually decreases with cooling from 300 K. The valence-band HAXPES show the metallic features of the pseudogap behavior near the Fermi edge in and above the intermediate-temperature phase due to V 2.5+-V 3+ charge fluctuation. The magnitude of the pseudogap increases from 300 K to 180 K in parallel with the gradual breaking of the V 2.5+-V 2.5+ bond and formation of trimers.

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Spin-singlet trimer state induced by competing orbital order in triangular-lattice BaV10O15

Cited by 15 publications

References 28 publications

Orbital reformation with vanadium trimerization ind2triangular lattice LiVO2revealed by51V NMR

Orbital reformation with vanadium trimerization ind2triangular lattice LiVO2revealed by51V NMR

Orbital states of V trimers in BaV10O15detected by resonant x-ray scattering

Temperature-dependent valence state within the metallic phase of BaV10O15 probed by hard x-ray photoelectron spectroscopy

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