In a quantum spin liquid, the magnetic moments of a material act like a liquid and remain disordered even at absolute zero. Materials that can form a quantum spin liquid have the potential for applications in quantum computing, data storage and high temperature superconductivity.
Many quantum spin liquids are based on magnetic atoms arranged in triangular planes, with magnetic interactions that are frustrated by this arrangement, such as the organic material κ-ET, which was investigated using detailed muon experiments at ISIS in 2011. Even at temperatures approaching absolute zero, the magnetic frustration and quantum fluctuations of the atomic magnetic moments cannot arrange themselves into a magnetically ordered state.
Other examples of when this effect was measured using muons at ISIS include investigations into YbMgGaO4 and TaS2. The recent study focussed on TbInO3, which contradicts its triangular structure through a combination of magnetic and structural interactions to form an altogether more exotic type of quantum spin liquid based on magnetic atoms arranged in hexagons.
Dr Lucy Clark and her team from the University of Liverpool (right) were forced to attack the problem with a combination of techniques; “In the case of TbInO3, the physics is particularly rich, and so we were especially driven to persevere. One key benefit of performing our study at the ISIS Facility was that we had access to both world-leading neutron and muon beamlines to help further our investigation."
Using HRPD to measure the neutron diffraction from the sample at temperatures down to 0.46K, the group saw a lack of magnetic Bragg scattering from the sample. This indicated the absence of long-range magnetic order in the material, and demonstrated that the magnetic atoms sit on two interpenetrating sites that ultimately form a honeycomb lattice, rather than a simple triangular one. Their experiments on MuSR and EMU also showed a lack of long-range magnetic order, and here they were able to measure the sample down to 0.1K.
“This material appears deceptively simple, with terbium spins decorating a two-dimensional, triangular architecture," said Professor Bruce Gaulin, Director of the Brockhouse Institute for Materials Research at McMaster University.
“But with the full complement of modern experimental techniques at our disposal, the low-temperature magnetism of this structure, based on two distinct terbium environments, exhibits an altogether exotic quantum disordered state of matter — an unexpected and exciting result."
Dr Clark adds; “Our study shows that TbInO3 is a fascinating magnetic material, and one most likely to have many more intriguing properties for us yet to uncover."
Find out more about other research carried out at ISIS by reading previous highlights from HRPD, EMU and MuSR.
This research was published in Nature Physics.