K. Yu. Povarov

Quantum spin chains with frustration due to Dzyaloshinskii-Moriya interactions

The properties of two quantum spin chain materials, K 2 CuSO 4 Cl 2 and K 2 CuSO 4 Br 2 , are studied by a variety of experimental techniques, including bulk measurements, neutron spectroscopy, and electron spin resonance. The hierarchy of relevant terms in the magnetic Hamiltonian is established. It is shown that these two compounds feature substantial Dzyaloshinskii-Moriya interactions that are uniform within each chain, but antiparallel in adjacent chains. The result is a peculiar type of frustration of interchain interactions, which leads to an unusual field-temperature phase diagram.

High-field magnetic resonance of spinons and magnons in the triangular lattice S=1/2 antiferromagnet Cs2CuCl4

The electron spin resonance doublet indicating the width of the two spinon continuum in a spin-1/2 triangular-lattice Heisenberg antiferromagnet Cs2CuCl4 was studied in high magnetic field. The doublet was found to collapse in a magnetic field of a half of the saturation field. The collapse of the doublet occurs via vanishing of the high frequency component in a qualitative agreement with the theoretical prediction for the S=1/2 chain. The field of the collapse is, however, much lower than expected for the S=1/2 chain. This is proposed to be due to the destruction of frustration of interchain exchange bonds in a magnetic field, which restores the 2D character of this spin system. In the saturated phase the mode with the Larmor frequency and a much weaker mode downshifted for 119~GHz are observed. The weak mode is of exchange origin, it demonstrates a positive frequency shift at heating corresponding to the repulsion of magnons in the saturated phase.

Scaling of temporal correlations in an attractive Tomonaga-Luttinger spin liquid

We report temperature-dependent neutron scattering measurements of the local dynamic structure factor in the quantum spin ladder (C

Finite-temperature correlations in a quantum spin chain near saturation

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Multiferroic phases of the frustrated quantum spin-chain compound linarite

H

Electron spin resonance in a model S=1/2 chain antiferromagnet with a uniform Dzyaloshinskii--Moriya interaction

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The tunable quantum spin ladder Cu(Qnx)(Cl(1−x)Brx)2

N)

Switching of anisotropy and phase diagram of the Heisenberg square-latticeS=12antiferromagnet Cu(pz)2(ClO4)2

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Magnetic resonance in the ordered phases of the two-dimensional frustrated quantum magnet Cs 2 CuCl 4

CuBr

Anisotropic magnetic interactions and spin dynamics in the spin-chain compound Cu(py)2Br2 : An experimental and theoretical study

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