Magnetic correlations in YBaCo4O7 probed by single-crystal neutron scattering

TL;DR

This study investigates magnetic correlations in YBaCo4O7 using neutron scattering, revealing quasi-one-dimensional order along c-axis and short-range in-plane correlations, highlighting a new class of frustrated magnetic systems.

Contribution

It provides the first detailed neutron scattering analysis of YBaCo4O7, demonstrating how out-of-plane coupling influences in-plane degeneracy in a frustrated system.

Findings

Long-range correlations along c-axis due to bipyramids

Rapid decay of in-plane spin correlations, indicative of spin-liquid behavior

YBaCo4O7 exemplifies a new frustrated system class with unique coupling effects

Abstract

We have studied the frustrated system YBaCo4O7 generally described as an alternating stacking of Kagome and triangular layers of magnetic ions on a trigonal lattice, by single crystal neutron diffraction experiments above the Neel ordering transition. Experimental data reveals pronounced magnetic diffuse scattering, which is successfully modeled by direct Monte-Carlo simulations. Long-range magnetic correlations are found along the c-axis, due to the presence of corner-sharing bipyramids, creating quasi one-dimensional order at finite temperature. In contrast, in the Kagome layers ab-plane, the spin-spin correlation function -displaying a short-range 120 degrees configuration- decays rapidly as typically found in spin-liquids. YBaCo4O7 experimentally realizes a new class of two-dimensional frustrated systems where the strong out-of-plane coupling does not lift the in-plane degeneracy, but instead act as an external "field".