Spin-Liquid State in the S = 1/2 Hyperkagome Antiferromagnet Na4Ir3O8

TL;DR

This paper reports the discovery of a three-dimensional spin-liquid state in the hyperkagome antiferromagnet Na4Ir3O8, characterized by the absence of magnetic order down to very low temperatures and field-independent specific heat.

Contribution

It provides experimental evidence for a 3D spin-liquid state in Na4Ir3O8, a hyperkagome lattice system, expanding understanding of frustrated quantum magnets.

Findings

No magnetic order observed down to 2 K

Large low-temperature specific heat independent of magnetic field

Evidence suggests a 3D spin-liquid ground state

Abstract

A spinel related oxide, Na4Ir3O8, was found to have a three dimensional network of corner shared Ir4+ (t2g^5) triangles. This gives rise to an antiferromagnetically coupled S = 1/2 spin system formed on a geometrically frustrated hyperkagome lattice. Magnetization M and magnetic specific heat Cm data showed the absence of long range magnetic ordering at least down to 2 K. The large Cm at low temperatures is independent of applied magnetic field up to 12 T, in striking parallel to the behavior seen in triangular and kagome antiferromagnets reported to have a spin-liquid ground state. These results strongly suggest that the ground state of Na4Ir3O8 is a three dimensional manifestation of a spin liquid.