Experimental Realization of a Quantum Breathing Pyrochlore Antiferromagnet

TL;DR

This paper reports the synthesis and characterization of a new Yb-based material that serves as the first experimental model of a quantum antiferromagnet on a breathing pyrochlore lattice, revealing unique magnetic properties.

Contribution

The study introduces a novel Yb-based compound as the first experimental realization of a quantum breathing pyrochlore antiferromagnet, with detailed magnetic characterization.

Findings

Large magnetic entropy remains at low temperature.

Formation of doubly degenerate singlet states in small Yb tetrahedra.

Behavior well described by a pseudospin-1/2 tetrahedron model.

Abstract

The synthesis and characterization of a new Yb-based material Ba3Yb2Zn5O11 are reported. This material is identified as the first model system of a pseudospin-1/2 quantum antiferromagnet on "breathing" pyrochlore lattice characterized by an alternating array of small and large Yb tetrahedra. Despite dominant antiferromagnetic interactions J ~ 7 K, a large amount of magnetic entropy (25%) remains at 0.38 K, indicating that each small Yb tetrahedron forms a unique doubly degenerate singlet state. These results are well described by the Heisenberg pseudospin-1/2 single tetrahedron model.