Orbital switching in a frustrated magnet

Yoshida, Hiroyuki; Yamaura, Jun‐ichi; Isobe, Masaaki; Okamoto, Yoshio; Nilsen, Gøran J.; Hiroi, Zenji

doi:10.1038/ncomms1875

Cited by 70 publications

(99 citation statements)

References 26 publications

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“…The heat capacity measurements on single crystals indicate two peaks at 0.8 and 1.2 K [30]. Although the two-step transition is not clear in the temperature dependence of the NMR spectra, two anomalies are observed in the temperature dependence of 1/T 1 .…”

Section: B Phase Boundaries In the Magnetic Field Perpendicular To Tmentioning

confidence: 89%

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Spin dynamics in the high-field phases of volborthite

et al. 2017

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We report single-crystal 51 V NMR studies on volborthite Cu3V2O7(OH)2·2H2O, which is regarded as a quasi-two-dimensional frustrated magnet with competing ferromagnetic and antiferromagnetic interactions. In the 1/3 magnetization plateau above 28 T, the nuclear spin-lattice relaxation rate 1/T1 indicates an excitation gap with a large effective g factor in the range of 4.6-5.9, pointing to magnon bound states. Below 26 T where the gap has closed, the NMR spectra indicate small internal fields with a Gaussian-like distribution, whereas 1/T1 shows a power-law-like temperature dependence in the paramagnetic state, which resembles a slowing down of spin fluctuations associated with magnetic order. We discuss the possibility of an exotic spin state caused by the condensation of magnon bound states below the magnetization plateau.PACS numbers: 75.30. Kz, 75.40.Gb, The possibilities of exotic states in quantum spin systems with frustrated interactions have attracted strong attention [1,2]. For example, the ground state of the spin-1/2 kagome antiferromagnet is believed to show no long-range magnetic order. Theories have proposed various ground states such as spin liquids [3][4][5] or valencebond-crystal states [6]. Other interesting states such as spin nematic states [7][8][9][10][11] and magnetization plateaus [12][13][14][15][16] are also expected in frustrated spin systems. Theories have predicted that a spin nematic state is realized near a fully polarized state of a frustrated spin system with competing ferromagnetic (FM) interactions J 1 and antiferromagnetic (AFM) interactions J 2 , [7][8][9][10][11]. In such systems, a spin nematic state is characterized by the condensation of two-magnon bound states. The search for a spin nematic phase has been performed by using high-field NMR near the fully polarized state of a quasione-dimensional J 1 -J 2 chain magnet LiCuVO 4 , although definitive results are not obtained yet [17,18].Volborthite Cu 3 V 2 O 7 (OH) 2 ·2H 2 O is a unique antiferromagnet with frustrated interactions [19], which contains layers of distorted kagome nets formed by Cu 2+ ions as shown in Fig. 1(a). Early high-field magnetization and NMR measurements in polycrystalline samples revealed three distinct magnetic phases I (B < 4.5 T), II (4.5 < B < 26 T), and III (26 T < B ) [20][21][22][23][24][25]. The magnetic properties were examined on the basis of the distorted kagome model [25][26][27][28], while the density func- * Present address: Max Plank Institute for Solid State Research, Heisenbergstrasse 1, 70569 Stuttgart, Germany tional theory (DFT) study of the C2/m structure proposed that frustration should be attributed to the competition between a FM J 1 and an AFM J 2 between second neighbors along the b axis [ Fig. 1(b)] [29]. Recently, single crystals were prepared and they have provided a further opportunity to study the unique magnetism of volborthite [30,31]. In the single crystals, the high-field NMR and magnetization measurements revealed two features remarkably different from those previou...

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Section: B Phase Boundaries In the Magnetic Field Perpendicular To Tmentioning

confidence: 89%

“…(a) Low temperature structure of P 21/a after the two structural transitions at 310 and 155 K [30][31][32]. The H and O sites are not shown.…”

mentioning

confidence: 99%

Spin dynamics in the high-field phases of volborthite

et al. 2017

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“…[17][18][19][20][21][22][23][24] However, the materials investigated, many of which are natural minerals, have individual problems such as spatial anisotropy of the exchange network 18,25 , exchange disorder due to ion substitution 26 and lattice distortion due to a structural phase transition. 27 For these reasons, there has been little clear experimental evidence demonstrating the nature of the ground state and the excitations for the spin- Heisenberg KLAF.…”

Section: -16mentioning

confidence: 99%

Quantum phase transition between disordered and ordered states in the spin-12kagome lattice antiferromagnet(Rb1−xCsx<

2015

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“…Orbital degrees of freedom play a key role in the physics of colossal magnetoresistance (CMR), [1][2][3][4] frustrated magnetism, 5,6 ferroelectricity, 7,8 spin glass formation, 9 and magnetoelectric coupling. 10 In all cases, it is the existence and nature of correlations between local orbital states that gives rise to the relevant phenomena of interest.…”

Section: Introductionmentioning

confidence: 99%

Local structure study of the orbital order/disorder transition inLaMnO3

et al. 2017

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We use a combination of neutron and X-ray total scattering measurements together with pair distribution function (PDF) analysis to characterise the variation in local structure across the orbital order-disorder transition in LaMnO3. Our experimental data are inconsistent with a conventional order-disorder description of the transition, and reflect instead the existence of a discontinuous change in local structure between ordered and disordered states. Within the orbital-ordered regime, the neutron and X-ray PDFs are best described by a local structure model with the same local orbital arrangements as those observed in the average (long-range) crystal structure. We show that a variety of meaningfully-different local orbital arrangement models can give fits of comparable quality to the experimental PDFs collected within the disordered regime; nevertheless, our data show a subtle but consistent preference for the anisotropic Potts model proposed in Phys Rev. B 79, 174106 (2009). The key implications of this model are electronic and magnetic isotropy together with the loss of local inversion symmetry at the Mn site. We conclude with a critical assessment of the interpretation of PDF measurements when characterising local symmetry breaking in functional materials.

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Orbital switching in a frustrated magnet

Cited by 70 publications

References 26 publications

Spin dynamics in the high-field phases of volborthite

Spin dynamics in the high-field phases of volborthite

Quantum phase transition between disordered and ordered states in the spin-12kagome lattice antiferromagnet(Rb1−xCsx<

Local structure study of the orbital order/disorder transition inLaMnO3

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