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Register a new userMagnetic properties and magnetic structure of the frustrated quasi-one-dimensional antiferromagnet SrCuTe$_2$O$_6$
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Magnetization measurements on single-crystal cubic SrCuTe$_2$O$_6$ with an applied magnetic field of along three inequivalent high symmetry directions $[100]$, $[110]$, and $[111]$ reveal weak magnetic anisotropy. The fits of the magnetic susceptibility to the result from a quantum Monte Carlo simulation on the Heisenberg spin-chain model, where the chain is formed via the dominant third-nearest-neighbor exchange interaction $J_3$, yield the intra-chain interaction $(J_3/k_B)$ between 50.12(7) K for the applied field along $[110]$ and 52.5(2) K along $[100]$ with about the same $g$-factor of 2.2. Single-crystal neutron diffraction unveils the transition to the magnetic ordered state as evidenced by the onset of the magnetic Bragg intensity at $T_textrm{N1}=5.25(9)$ K with no anomaly of the second transition at $T_textrm{N2}$ reported previously. Based on irreducible representation theory and magnetic space group analysis of powder and single-crystal neutron diffraction data, the magnetic structure in the Shubnikov space group $P4_132$, where the Cu$^{2+}$~$S=1/2$ spins antiferromagnetically align in the direction perpendicular to the spin chain, is proposed. The measured ordered moment of $0.52(6)~mu_B$, which represents 48% reduction from the expected value of $1~mu_B$, suggests the remaining influence of frustration resulting from the $J_1$ and $J_2$ bonds.
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SrCuTe$_2$O$_6$ consists of a 3-dimensional arrangement of spin-$frac{1}{2}$ Cu$^{2+}$ ions. The 1st, 2nd and 3rd neighbor interactions respectively couple Cu$^{2+}$ moments into a network of isolated triangles, a highly frustrated hyperkagome lattice consisting of corner sharing triangles and antiferromagnetic chains. Of these, the chain interaction dominates in SrCuTe$_2$O$_6$ while the other two interactions lead to frustrated inter-chain coupling giving rise to long range magnetic order at suppressed temperatures. In this paper, we investigate the magnetic properties in SrCuTe$_2$O$_6$ using muon relaxation spectroscopy and neutron diffraction and present the low temperature magnetic structure.
CaV$_2$O$_4$ is a spin-1 antiferromagnet, where the magnetic vanadium ions are arranged on quasi-one-dimensional (1D) zig-zag chains with potentially frustrated antiferromagnetic exchange interactions. High temperature susceptibility and single-crystal neutron diffraction measurements are used to deduce the non-collinear magnetic structure, dominant exchange interactions and orbital configurations. The results suggest that at high temperatures CaV$_2$O$_4$ behaves as a Haldane chain, but at low temperatures, orbital ordering lifts the frustration and it becomes a spin-1 ladder.
We investigated the crystal and magnetic structures of the spin-1/2 frustrated antiferromagnet Cu3Mo2O9 in which the spin system consists of antiferromagnetic chains and dimers. The space group at room temperature has been reported to be orthorhombic Pnma (No. 62). We infer that the space group above TN = 7.9 K is monoclinic P2_1/m (No. 11) from the observation of reflections forbidden in Pnma in x-ray powder diffraction experiments at room temperature. We determined the magnetic structure of Cu3Mo2O9 in neutron powder diffraction experiments. Magnetic moments on dimer sites lie in the ac planes. The magnitudes are 0.50 - 0.74 mu_B. Moments on chain sites may exist but the magnitudes are very small. The magnetic structure indicates that a partial disordered state is realized. We consider the origin of the magnetic structure, weak ferromagnetism, and electric polarization.
We report the low-temperature properties of SrNd$_2$O$_4$, a geometrically frustrated magnet. Magnetisation and heat capacity measurements performed on polycrystalline samples indicate the appearance of a magnetically ordered state at $T_{rm N}=2.28(4)$~K. Powder neutron diffraction measurements reveal that an afm state with the propagation vector QV is stabilised below this temperature. The magnetic order is incomplete, as only one of the two Nd$^{3+}$ sites carries a significant magnetic moment while the other site remains largely disordered. The presence of a disordered magnetic component below $T_{rm N}$ is confirmed with polarised neutron diffraction measurements. In an applied magnetic field, the bulk properties measurements indicate a phase transition at about 30~kOe. We construct a tentative $H$-$T$ phase diagram of sno from these measurements.
We present experimental and theoretical evidence that an interesting quantum many-body effect -- quasi-particle breakdown -- occurs in the quasi-one-dimensional spin-1/2 Ising-like ferromagnet CoNb$_2$O$_6$ in its paramagnetic phase at high transverse field as a result of explicit breaking of spin inversion symmetry. We propose a quantum spin Hamiltonian capturing the essential one-dimensional physics of CoNb$_2$O$_6$ and determine the exchange parameters of this model by fitting the calculated single particle dispersion to the one observed experimentally in applied transverse magnetic fields. We present high-resolution inelastic neutron scattering measurements of the single particle dispersion which observe anomalous broadening effects over a narrow energy range at intermediate energies. We propose that this effect originates from the decay of the one particle mode into two-particle states. This decay arises from (i) a finite overlap between the one-particle dispersion and the two-particle continuum in a narrow energy-momentum range and (ii) a small misalignment of the applied field away from the direction perpendicular to the Ising axis in the experiments, which allows for non-zero matrix elements for decay by breaking the $mathbb{Z}_2$ spin inversion symmetry of the Hamiltonian.
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