Metamagnetism and soliton excitations in the modulated ferromagnetic Ising chain CoV2O6

Abstract

We report a combination of physical property and neutron scattering measurements for polycrystalline samples of the one-dimensional spin chain compound CoV2O6. Heat capacity measurements show that an effective S = 1/2 state is found at low temperatures and that magnetic fluctuations persist up to ∼6.TN. Above TN= 6.3 K, measurements of the magnetic susceptibility as a function of T and H show that the nearest neighbour exchange is ferromagnetic. In the ordered state, we have discovered a crossover from a metamagnet with strong fluctuations between 5 K and TN to a state with a 1/3 magnetisation plateau at 2 < T < 5 K. We use neutron powder diffraction measurements to show that the AFM state has incommensurate long range order and inelastic time of flight neutron scattering to examine the magnetic fluctuations as a function of temperature. Above TN, we find two broad bands between 3.5 and 5 meV and thermally activated low energy features which correspond to transitions within these bands. These features show that the excitations are deconfined solitons rather than the static spin reversals predicted for a uniform FM Ising spin chain. Below TN, we find a ladder of states due to the confining effect of the internal field. A region of weak confinement below TN, but above 5 K, is identified which may correspond to a crossover between 2D and 3D magnetic ordering.

Neutron diffraction study of monoclinic brannerite-type CoV2O6

“…Magnetisation and neutron scattering measurements for the triclinic CoV 2 O 6 phase have recently been reported [3,15]. Similar transitions to the monoclinic form were found; an antiferromagnetic transition at T N ¼6.3 K; onset of 1/3 magnetisation plateau at 0.36 T and a transition at 0.59 T to full magnetisation, both at 2 K [3].…”

“…Metamagnetism and magnetization plateaus are among the unusual properties of low-dimensional magnetic oxides based on spin-3/2 ions such as Co 2 þ . 1/3 (of ferromagnetic) magnetization plateaus have been predicted and observed experimentally in spin-3/2 antiferromagnetic uniform chains [1,2] and are known to occur also in spin-3/2 ferromagnetic uniform chains [3].…”

Fermi surface topology and hot spot distribution in the Kondo lattice systemCeB6

“…Note that BaB 6 is measured in same experimental setup as CeB 6 and no hotspots are observed in the d-band of BaB 6 , which indicates that hotspots are not generic features of d-band in the hexaborides, but rather arise from the important role played by electron-electron correlation and low temperature magnetic fluctuation. We note that magnetic fluctuations can typically persist up to temperatures order of magnitude larger than transition temperature [39], which is also evidenced on the temperature dependent data [38]. Finally, we present the first-principle electronic structure of CeB 6 along the high-symmetry directions M -X-M and X-Γ-X in Fig.…”

Spin orders and lattice distortions of geometrically frustrated 6H-perovskites Ba3B′Ru2OSenn1, Kimber2, Arévalo‐López3 et al. 2013Phys. Rev. BSelf Cite3510623View full textAdd to dashboardCite

“…7(d)] and the reversal of magnetization proceeds via 1 3 -magnetization steps; ↑↑↑→↑↓↑→↓↓↓→↓↑↓→↑↑↑ as magnetic field is cycled up → down → up. Two models for the ↑↓↑ 1 3 -magnetization phase are plausible-an order of 2↑:1↓-spin chains parallel to the c axis, as observed in some frustrated triangular lattices such as CoV 2 O 6 , [22][23][24] or an ↑↓↑ order of successive Nd planes perpendicular to c. High-field neutron diffraction will be needed to distinguish between these possibilities.…”