Magnetic properties of the $S$ = 1/2 antiferromagnetic spin-chain $\alpha-$Cu$_{2}$V$_{2}$O$_{7}$

Magnetic properties of the $S = 1/2$ antiferromagnetic spin-chain, $\alpha-$Cu$_{2}$V$_{2}$O$_{7}$, have been studied using magnetization and neutron scattering measurements on powder and single-crystal samples. Magnetic susceptibility reveals a Curie-Weiss temperature of $\Theta$ = -73.2(9) K with a magnetic phase transition at $T_{N}$ = 33 K while the Bonner-Fisher fit to the magnetic susceptibility for $T > T_{N}$ with magnetic field perpendicular to the crystallographic $a-$axis yields the intra-chain coupling of $\left| J\right| /k$ = 46.0(2) K. Small ferromagnetism below $T_{N}$ is due to spin-canting caused by Dzyaloshinskii-Moriya interactions. Analysis of the neutron diffraction data reveals that the Cu$^{2+}$ spins are coupled antiferromagnetically along zigzag chains, which run alternately along [011] and [01-1] directions. The ordered moment of 0.925(3) $\mu_{B}$ is predominantly along the $a-$axis. Our recent inelastic neutron scattering, which reveals atypical magnetic excitations centered at commensurate wave vectors (0, $\pm$0.25, 0) around the magnetic zone center, will also be discussed.