arXiv subjects

W. J. L. Buyers

Publications and source records attributed to W. J. L. Buyers.

39 records · Page 3Linked to original sources

arXiv2000

Multi-particle States in Spin-1 Chain System CsNiCl3

A continuum of magnetic states has been observed by neutron scattering from the spin-1 chain compound CsNiCl3 in its disordered gapped one-dimensional phase. Results using both triple-axis and time-of-flight spectrometers show that around the antiferromagnetic point Qc=pi, the continuum lies higher in energy than the Haldane gapped excitations. At 6K the integrated intensity of the continuum is about 12(2)% of the total spectral weight. This result is considerably larger than the 1-3% weight predicted by the non-linear sigma model for the 3-particle continuum.

cond-mat.str-el↗

arXiv1996

Influence of a magnetic field on the antiferromagnetic order in UPt_3

A neutron diffraction experiment was performed to investigate the effect of a magnetic field on the antiferromagnetic order in the heavy fermion superconductor UPt_3. Our results show that a field in the basal plane of up to 3.2 Tesla, higher than H_c2(0), has no effect: it can neither select a domain nor rotate the moment. This has a direct impact on current theories for the superconducting phase diagram based on a coupling to the magnetic order.

cond-mat↗

arXiv1996

The Ising-Kondo lattice with transverse field: an f-moment Hamiltonian for URu2Si2?

We study the phase diagram of the Ising-Kondo lattice with transverse magnetic field as a possible model for the weak-moment heavy-fermion compound URu2Si2, in terms of two low-lying f singlets in which the uranium moment is coupled by on-site exchange to the conduction electron spins. In the mean-field approximation for an extended range of parameters, we show that the conduction electron magnetization responds logarithmically to f-moment formation, that the ordered moment in the antiferromagnetic state is anomalously small, and that the Neel temperature is of the order observed. The model gives a qualitatively correct temperature-dependence, but not magnitude, of the specific heat. The majority of the specific heat jump at the Neel temperature arises from the formation of a spin gap in the conduction electron spectrum. We also discuss the single-impurity version of the model and speculate on ways to increase the specific heat coefficient. In the limits of small bandwidth and of small Ising-Kondo coupling, we find that the model corresponds to anisotropic Heisenberg and Hubbard models respectively.

cond-mat↗