arXiv subjects

M. Hälg

Publications and source records attributed to M. Hälg.

4 recordsLinked to original sources

arXiv2018

Spin gap in a quasi-1D S=1/2 antiferromagnet K2CuSO4Cl2

Electron spin resonance experiments in the quasi-1D S=1/2 antiferromagnet K$_2$CuSO$_4$Cl$_2$ reveal opening of a gap in absence of magnetic ordering, as well as an anisotropic shift of the resonance magnetic field. These features of magnetic excitation spectrum are explained by a crossover between a gapped spinon-type doublet ESR formed in a 1D antiferromagnet with uniform Dzyaloshinskii-Moriya interaction and a Larmor-type resonance of a quasi-1D Heisenberg system

cond-mat.str-el↗

arXiv2015

Finite-temperature scaling of spin correlations in a partially magnetized Heisenberg $S=1/2$ chain

Inelastic neutron scattering is employed to study transverse spin correlations of a Heisenberg $S=1/2$ chain compound in a magnetic field of 7.5 T. The target compound is the antiferromagnetic Heisenberg $S=1/2$ chain material 2(1,4-Dioxane)$\cdot$2(H$_2$O)$\cdot$CuCl$_2$, or CuDCl for short. The validity and the limitations of the scaling relation for the transverse dynamic structure factor are tested, discussed and compared to the Tomonaga-Luttinger spin liquid theory and to Bethe-ansatz results for the Heisenberg model.

cond-mat.str-el↗

arXiv2015

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

The electron spin resonance spectrum of a quasi 1D S=1/2 antiferromagnet K2CuSO4Br2 was found to demonstrate an energy gap and a doublet of resonance lines in a wide temperature range between the Curie--Weiss and Neèl temperatures. This type of magnetic resonance absorption corresponds well to the two-spinon continuum of excitations in S=1/2 antiferromagnetic spin chain with a uniform Dzyaloshinskii--Moriya interaction between the magnetic ions. A resonance mode of paramagnetic defects demonstrating strongly anisotropic behavior due to interaction with spinon excitations in the main matrix is also observed.

cond-mat.str-el↗

arXiv2015

Finite-temperature scaling of spin correlations in an experimental realization of the one-dimensional Ising quantum critical point

Inelastic neutron scattering is used to study the finite-temperature scaling behavior of the local dynamic structure factor in the quasi-one-dimensional quantum antiferromagnet NTENP ($\text{Ni(N,N'-bis(3-aminopropyl)propane-1,3-diamine)(}μ\text{-NO}_2\text{)ClO}_4$), at its field-induced Ising quantum critical point. The validity and the limitations of the theoretically predicted scaling relations are tested.

cond-mat.str-el↗