NaV2O4: A Quasi-1D Metallic Antiferromagnet with Half-Metallic Chains

Abstract

NaV 2 O 4 crystals were grown under high pressure using a NaCl flux, and the crystals were characterized with X-ray diffraction, electrical resistivity, heat capacity, and magnetization. The structure of NaV 2 O 4 consists of double chains of edge-sharing VO 6 octahedra. The resistivity is highly anisotropic, with the resistivity perpendicular to the chains more than 20 times greater than that parallel to the chains.Magnetically, the intrachain interactions are ferromagnetic and the interchain interactions are antiferromagnetic; 3D antiferromagnetic order is established at 140 K. First principles electronic structure calculations indicate that the chains are half metallic. Interestingly, the case of NaV 2 O 4 seems to be a quasi-1D analogue of what was found for half-metallic materials.

High-Resolution Photoemission Study of NaV2O4

“…6) The X-ray diffraction measurement confirmed that NaV 2 O 4 is a mixed-valent V 3:5þ (3d 1:5 ) compound consisting of double chains of edgesharing VO 6 octahedra along the b axis. The intra-chain interaction is ferromagnetic while the inter-chain interaction is antiferromagnetic (AF), leading to the 3D AF order at around 140 K. NaV 2 O 4 exhibits a quasi-1D metallic nature below the AF transition temperature T N with the metallic conductivity parallel to the chains more than 20 times larger than that perpendicular to the chains.…”

“…6) The resistivity is highly anisotropic with the conductivity parallel to the chains more than 20 times larger than that perpendicular to the chains at very low temperatures. The anisotropy is gradually reduced in the AF state with increasing temperature while it becomes almost independent of temperature above T N .…”

“…It is remarked that the V 3d band is well separated from the O 2p band also in NaV 2 O 4 as in other vanadium oxides. [12][13][14][15][16] Since the band calculation predicts that the V 3d states would be affected by the magnetic order, 6) we have performed PES measurements near E F at various temperatures across T N . We compare in Fig.…”

“…2, the spectral lineshape near E F is obviously changed with increasing temperature across T N in qualitatively good agreement with the band calculation. 6) Since it is known that the PES measurement with the He I resonance line is surface-sensitive and the obtained spectrum may not represent the intrinsic bulk nature of NaV 2 O 4 , we performed PES measurements with the Xe I resonance line (h ¼ 8:437 eV). 7) In Fig.…”

Metal-insulator transition in the hollanditeK2V8OShimizu1, Okai2, Itoh3 et al. 2011Phys. Rev. B23080View full textAdd to dashboardCite

“…Indeed, a Heisenberg model of the zigzag ladder predicts degenerated ground states, including nematic, 3,4 topological, 5 chiral, 6 incommensurate magnetic orders, 7 the spin-Bose metal, 8 and the field-induced orbital current. 9 In the presence of the orbital degrees of freedom with the moderate electron correlation and the electron-phonon coupling, various phase transitions have been found, such as the valence bond 10,11 and ferromagnetic 12 orders in hollandites A 2 M 8 O 16 , and the antiferromagnetic metal 13 and insulator 14 in pyroferites AM 2 O 4 , where A are alkaline metals and M are transition metals. To understand these phase transitions, the electron correlation and the orbital occupancy would be the dominant parameters, which should be revealed experimentally.…”