C. Maitland | Searcharxiv

arXiv2016

Synthetic magnetism for photon fluids

We develop a theory of artificial gauge fields in photon fluids for the cases of both second-order and third-order optical nonlinearities. This applies to weak excitations in the presence of pump fields carrying orbital angular momentum, and is thus a type of Bogoliubov theory. The resulting artificial gauge fields experienced by the weak excitations are an interesting generalization of previous cases and reflect the PT-symmetry properties of the underlying non-Hermitian Hamiltonian. We illustrate the observable consequences of the resulting synthetic magnetic fields for examples involving both second-order and third-order nonlinearities.

cond-mat.quant-gas↗

arXiv2008

Isotope effect in quasi-two-dimensional metal-organic antiferromagnets

Although the isotope effect in superconducting materials is well-documented, changes in the magnetic properties of antiferromagnets due to isotopic substitution are seldom discussed and remain poorly understood. This is perhaps surprising given the possible link between the quasi-two-dimensional (Q2D) antiferromagnetic and superconducting phases of the layered cuprates. Here we report the experimental observation of shifts in the Néel temperature and critical magnetic fields ($ΔT_{\rm N}/T_{\rm N}\approx 4%$; $ΔB_{\rm c}/B_{\rm c}\approx 4%$) in a Q2D organic molecular antiferromagnets on substitution of hydrogen for deuterium. These compounds are characterized by strong hydrogen bonds through which the dominant superexchange is mediated. We evaluate how the in-plane and inter-plane exchange energies evolve as the hydrogens on different ligands are substituted, and suggest a possible mechanism for this effect in terms of the relative exchange efficiency of hydrogen and deuterium bonds.

cond-mat.str-el↗