Structural and magnetic aspects of the nanotube system ${\text{Na}}_{2\ensuremath{-}x}{\text{V}}_{3}{\text{O}}_{7}$

Structural and magnetic aspects of the nanotube system ${Na}_{2 - x} V_{3} O_{7}$

O. Zaharko, J. L. Gavilano, Th. Strässle, C. F. Miclea, A. C. Mota, Y. Filinchuk, D. Chernyshov, P. P. Deen, B. Rahaman, T. Saha-Dasgupta, R. Valentí, Y. Matsushita, A. Dönni, and H. Kitazawa

Phys. Rev. B 78, 214426 – Published 18 December 2008

Abstract

We present experimental results of low-temperature x-ray synchrotron diffraction, neutron-scattering, and very low-temperature (mK range) bulk measurements on the nanotube system ${Na}_{2} V_{3} O_{7}$ . The crystal structure determined from our data is similar to the previously proposed model [P. Millet et al., J. Solid State Chem. 147, 676 (1999)], but also deviates from it in significant details. The structure comprises of nanotubes along the $c$ axis formed by stacking units of two V rings buckled in the $a b$ plane. The space group is $P \bar{3}$ and the composition is nonstoichiometric, ${Na}_{2 - x} V_{3} O_{7}$ , $x = 0.17$ . The thermal evolution of the lattice parameters reveals anisotropic lattice compression on cooling. Neutron-scattering experiments monitor a very weak magnetic signal at energies from $- 20$ to 9 meV. Magnetic susceptibility, specific-heat measurements, and decay of remanent magnetization in the 30–300 mK range reveal that the previously observed transition at $\approx 76 mK$ is spin-glass like with no long-range order. Presented experimental observations do not support models of isolated clusters but are compatible with a model of odd-legged $S = 1 / 2$ spin tubes possibly segmented into fragments with different lengths.

Figure
Figure
Figure
Figure
Figure
Figure
Figure

3 More

Received 27 August 2008

DOI:https://doi.org/10.1103/PhysRevB.78.214426

Authors & Affiliations

O. Zaharko ^*, J. L. Gavilano, and Th. Strässle

Laboratory for Neutron Scattering, ETH Zurich & Paul Scherrer Institut, CH-5232 Villigen, Switzerland

C. F. Miclea

Max-Planck-Institute for Chemical Physics of Solids (MPICPfS), D-01187 Dresden, Germany

A. C. Mota

Laboratory for Solid State Physics, ETH-Hönggerberg, CH-8093 Zürich, Switzerland and Max-Planck-Institute for Chemical Physics of Solids (MPICPfS), D-01187 Dresden, Germany

Y. Filinchuk and D. Chernyshov

Swiss-Norwegian Beamlines, ESRF, F-38042 Grenoble Cedex 9, France

P. P. Deen

Institut Laue-Langevin, 156X, F-38042 Grenoble Cedex 9, France

B. Rahaman and T. Saha-Dasgupta

S.N. Bose National Centre for Basic Sciences, JD Block, Sector 3, Salt Lake City, Kolkata 700098, India

R. Valentí

Institute of Theoretical Physics, University of Frankfurt, D-60438 Frankfurt, Germany

Y. Matsushita, A. Dönni, and H. Kitazawa

National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0047, Japan

^*Oksana.Zaharko@psi.ch

Click to Expand

Article Text (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand

Issue

Vol. 78, Iss. 21 — 1 December 2008

Reuse & Permissions

Access Options

Author publication services for translation and copyediting assistance advertisement

Authorization Required

Other Options

Images

Figure 1
(Color online) (a) [001] projection of the ${Na}_{2} V_{3} O_{7}$ structure. (b) and (c) Arrangement of ${VO}_{5}$ square pyramids forming buckled rings (slices A and B) within the unfolded nanotube in the model of Millet et al. (Ref. 1) (b) and in our model (c). (d) Four different families of exchange couplings $J_{1}$ (gray), $J_{2}$ (white), $J_{3}$ (black), and $J_{4}$ (black dashed). The three sites of vanadium are denoted by V1, V2, V3 in (b), (c). In (d) the notation 11, 12, . . . 34 is used with the first index numbering the site, the second index numbering atoms within the site. Oxygen and sodium atoms are omitted for clarity.Reuse & Permissions
Figure 2
(Color online) Thermal expansion of the lattice parameters $a$ (red/gray filled symbols) and $c$ (blue/gray empty symbols) from x-ray powder diffraction. Inset: the $a / c$ ratio calculated from the SNBL (green/light gray ○しろまる), SLS (violet/gray ◇) powder patterns, and SNBL (red/gray ◻) single-crystal data.Reuse & Permissions
Figure 3
(Color online) Thermal evolution of the V-V distances calculated from single-crystal x-ray diffraction at 200, 80, and 16 K. Top: first intra-ring distances, bottom: second intra-ring ( $V_{11} {-V}_{22}$ , $V_{21} {-V}_{31}$ , black), first ( $V_{31} {-V}_{24}$ , $V_{11} {-V}_{23}$ , red), and second ( $V_{11} {-V}_{12}$ , $V_{31} {-V}_{33}$ , orange) inter-ring distances.Reuse & Permissions
Figure 4
(Color online) Top: total, nuclear-spin incoherent, and magnetic scattering at 120 K measured on D7 with $λ_{i} = 3.1 Å$ . Inset: the ( $Q$ , $ω$ ) window accessible during the experiment is shown by the dashed area. Bottom: absolute magnetic scattering at 1.8, 120, and 300 K.Reuse & Permissions
Figure 5
(Color online) Comparison of the magnetic scattering at 2 K measured on D7 and the calculated paramagnetic signal of $V^{4 +}$ , both in absolute scale. Calculated low-lying excitations of an isolated nine-member ring and of an isolated dimer are given in arbitrary units.Reuse & Permissions
Figure 6
(Color online) Inelastic neutron scattering (INS) spectra of ${Na}_{2 - x} V_{3} O_{7}$ at 1.5 K and 120 K measured on FOCUS with $λ_{i} = 1.7 Å$ . The intensity has been integrated over the momentum-transfer range $2.1 < Q < 5.7 Å^{- 1}$ . Inset: $Q$ dependence at 120 K for $2.6 < Q_{1} < 3.4 Å^{- 1}$ and $4.1 < Q_{2} < 4.9 Å^{- 1}$ .Reuse & Permissions
Figure 7
(Color online) Temperature and frequency dependence of real $χ^{'}$ and imaginary $χ^{''}$ components of ac susceptibility in mK temperature range.Reuse & Permissions
Figure 8
(Color online) Magnetic part of the specific heat divided by temperature $C_{m} / T$ versus $T$ for different fields. Inset: $C_{m}$ versus $T$ below 1 K.Reuse & Permissions
Figure 9
(Color online) Temperature and frequency dependence of the normalized remanent magnetization $m_{rem} = \frac{M_{t} - M_{\infty}}{M_{0} - M_{\infty}}$ . Top: the same cooling field of 100 Oe has been used and measurement performed at different temperatures. Inset: $M_{rem}$ (arb. units) versus $T$ . Bottom: different cooling fields of 100 and 10 Oe have been used and measurement was performed at 40 mK. Inset: $A$ versus $T^{β}$ .Reuse & Permissions
Figure 10
(Color online) Temperature dependence of inverse susceptibility obtained from our experiment (symbols) and calculated (solid line) for an isolated nine-member ring with $J_{1} = - 160 K$ and $J_{2} = - 90 K$ . Inset: energy distribution of 512 levels of the ring as a function of the total spin $S$ . Calculations were performed using the ALPS program (Ref. 28).Reuse & Permissions

Physical Review B

covering condensed matter and materials physics

Structural and magnetic aspects of the nanotube system ${Na}_{2 - x} V_{3} O_{7}$

O. Zaharko, J. L. Gavilano, Th. Strässle, C. F. Miclea, A. C. Mota, Y. Filinchuk, D. Chernyshov, P. P. Deen, B. Rahaman, T. Saha-Dasgupta, R. Valentí, Y. Matsushita, A. Dönni, and H. Kitazawa

Phys. Rev. B 78, 214426 – Published 18 December 2008

Abstract

Authors & Affiliations

Article Text (Subscription Required)

References (Subscription Required)

Issue

Access Options

Authorization Required

Other Options

Images

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Physical Review B

covering condensed matter and materials physics

Structural and magnetic aspects of the nanotube system Na2−xV3O7

O. Zaharko, J. L. Gavilano, Th. Strässle, C. F. Miclea, A. C. Mota, Y. Filinchuk, D. Chernyshov, P. P. Deen, B. Rahaman, T. Saha-Dasgupta, R. Valentí, Y. Matsushita, A. Dönni, and H. Kitazawa

Phys. Rev. B 78, 214426 – Published 18 December 2008

Abstract

Authors & Affiliations

Article Text (Subscription Required)

References (Subscription Required)

Issue

Access Options

Authorization Required

Other Options

Download & Share

Images

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Log In

Search

Article Lookup

Paste a citation or DOI

Enter a citation

Structural and magnetic aspects of the nanotube system ${Na}_{2 - x} V_{3} O_{7}$