Short-range correlations in the magnetic ground state of Na₄Ir₃O₈

Phys Rev Lett. 2014 Dec 12;113(24):247601. doi: 10.1103/PhysRevLett.113.247601. Epub 2014 Dec 8.

Abstract

The magnetic ground state of the J(eff)=1/2 hyperkagome lattice in Na₄Ir₃O₈ is explored via combined bulk magnetization, muon spin relaxation, and neutron scattering measurements. A short-range, frozen state comprised of quasistatic moments develops below a characteristic temperature of T(F)=6 K, revealing an inhomogeneous distribution of spins occupying the entirety of the sample volume. Quasistatic, short-range spin correlations persist until at least 20 mK and differ substantially from the nominally dynamic response of a quantum spin liquid. Our data demonstrate that an inhomogeneous magnetic ground state arises in Na₄Ir₃O₈ driven either by disorder inherent to the creation of the hyperkagome lattice itself or stabilized via quantum fluctuations.