Quantum spin liquids have no magnetic order, even at temperatures approaching zero kelvin, and have the potential for use in new technologies such as quantum computing. In this study, the scientists focussed on the candidate material Ba4NbIr3O12. They used a diverse range of techniques at facilities around the world including ISIS, Diamond Light Source, NSRRC in Taiwan and SPring-8 in Japan to uncover its low temperature magnetic behaviour.
Materials containing heavier transition metal oxides show a range of novel magnetic and electronic properties, due to the competing spin-orbital interactions, crystal field and geometric frustration. Although some oxides have been extensively studied, there are others that have attracted less attention, despite their potential for hosting quantum magnetic phases.
The research team brings together scientists from the UK, Korea, Italy, Belgium, Germany, Japan, Taiwan and India. In this study, published in Physical Review Materials, they investigated the lesser-studied trimer iridate Ba4NbIr3O12, prompted by their previous investigation into Ba4NbRh3O12 that revealed a quantum spin liquid ground state.
Muon spectroscopy is an extremely sensitive microscopic probe of small static local fields that arise from any weak long-range order or spin freezing. It can also be used to determine the nature of the local spin dynamics and internal magnetic fields of a magnetically disordered quantum material.
Their measurements, including those from muon spectroscopy (µSR) on the MuSR beamline at ISIS, indicate the absence of long-range magnetic order down to the lowest measurement temperature of 0.05 K. Instead, their longitudinal field µSR study showed the material still had persistent spin dynamics at 0.1 K, and therefore that a quantum spin liquid is present.
They also used the ISIS Material Characterisation Lab to carry out mK heat capacity and magnetic susceptibility measurements. These also supported a quantum spin liquid ground state with gapless spinon excitations.
“We hope that our work will generate additional theoretical and experimental interest in the 3D geometrically frustrated trimer based quadrupole perovskite family of iridates, rhodates and ruthenates as candidate QSL materials" says ISIS scientist and paper author Devashi Adroja.
Fig.1 (Left) Crystal structure of Ba4NbIr3O12 and (Right) Results from mSR investigations revealing a dynamical quantum spin-liquid ground state
