A team led by Professor KIM Bumjoon at the IBS Center for Artificial Low Dimensional Electronic Systems in South Korea has made the first observation of a “spin-nematic phase”, a magnetic equivalent of liquid crystal. This discovery, made possible by advancements in synchrotron facility development, could have significant implications for quantum computing and information technologies, according to Prof. CHO Gil Young, a co-author of the study. The team used a series of optical techniques to observe spin quadrupoles in a spin-nematic phase, a state previously predicted but never directly observed. The research also suggests potential for high-temperature superconductivity.
Discovery of Magnetic Liquid Crystal
The first observation of a “spin-nematic phase”, a magnetic equivalent of liquid crystal, has been made in a quantum spin system. Liquid crystal, a state of matter that exhibits properties of both liquid and solid, is widely used in LCD devices. The magnetic equivalent, the “spin-nematic phase”, has been elusive due to the insensitivity of most conventional experimental techniques to spin quadrupoles, the defining features of this phase.
A team of researchers led by Professor KIM Bumjoon at the IBS Center for Artificial Low Dimensional Electronic Systems in South Korea has now directly observed spin quadrupoles. This breakthrough was made possible by significant advancements in synchrotron facility development over the last few decades.
Study on Square-Lattice Iridium Oxide Sr2IrO4
The researchers focused their study on square-lattice iridium oxide Sr2IrO4, a material known for its antiferromagnetic dipolar order at low temperatures. They discovered the coexistence of a spin quadrupolar order, which becomes observable through its interference with the magnetic order. This interference signal was detected by ‘circular-dichroic resonant x-ray diffraction’, an advanced x-ray technique employing circularly polarized x-ray beam.
Collaboration with Argonne National Laboratory
To further verify their discovery, the researchers collaborated with Argonne National Laboratory in the US to construct a resonant inelastic x-ray scattering beamline in Pohang Accelerator Laboratory over the last four years. They used ‘polarization-resolved resonant inelastic x-ray scattering’ to reveal that the magnetic excitations significantly deviate from the behaviors anticipated for those in conventional magnets.
Use of Optical Techniques
The researchers also used a series of optical techniques, including Raman spectroscopy and magneto-optical Kerr effect measurement, to show that the formation of the spin quadrupole moments occurs at higher temperatures than the magnetic order. Within this temperature range, the iridium oxide has only spin quadrupole moments but no magnetic order, realizing a spin-nematic phase.
Implications for Quantum Computing and Information Technologies
The discovery of the spin-nematic phase holds significant implications for quantum computing and information technologies, according to Prof. CHO Gil Young, a co-author of the study and professor at Pohang University of Science and Technology. The spin-nematic phase also has potential for high-temperature superconductivity due to the high entanglement of the spins, a key ingredient for high-temperature superconductivity as suggested by physicist P. W. Anderson.
Potential for High-Temperature Superconductivity
Iridium oxide Sr2IrO4 has been extensively studied because of its striking similarities with the copper-oxide high-temperature superconducting system. This fuels a growing interest in this material as a potentially new high-temperature superconducting system, as well as its relation to the spin-nematic phase.
About the Institute for Basic Science (IBS)
The Institute for Basic Science (IBS) was founded in 2011 by the government of the Republic of Korea with the sole purpose of driving forward the development of basic science in South Korea. IBS has 6 research institutes and 33 research centers as of November 2023. There are eleven physics, three mathematics, five chemistry, nine life science, two earth science, and three interdisciplinary research centers.
“This research was feasible because the infrastructure and capabilities of x-ray experiments in South Korea had reached a globally competitive level,” says Prof. KIM Bumjoon, corresponding author of this study.
“The discovery of the spin-nematic phase also holds significant implications for quantum computing and information technologies,” adds Prof. CHO Gil Young, a co-author of this study and professor at Pohang University of Science and Technology.
Summary
A team of researchers has made the first-ever observation of a “spin-nematic phase”, a magnetic equivalent of liquid crystal, in a quantum spin system. This discovery could have significant implications for quantum computing and high-temperature superconductivity.
- A team of researchers led by Professor KIM Bumjoon at the IBS Center for Artificial Low Dimensional Electronic Systems in South Korea has made the first observation of a “spin-nematic phase”, a magnetic analogue of liquid crystal.
- The team used a material known as square-lattice iridium oxide Sr2IrO4, which is known for its antiferromagnetic dipolar order at low temperatures.
- The researchers were able to observe spin quadrupoles, a defining feature of the spin-nematic phase, using advanced x-ray techniques.
- The discovery was verified through ‘polarization-resolved resonant inelastic x-ray scattering’, a process that revealed significant deviations from behaviours expected in conventional magnets.
- The researchers collaborated with Argonne National Laboratory in the US to construct a resonant inelastic x-ray scattering beamline in Pohang Accelerator Laboratory.
- The discovery of the spin-nematic phase could have significant implications for quantum computing and information technologies, according to Prof. CHO Gil Young, a co-author of the study.
- The spin-nematic phase also has potential for high-temperature superconductivity due to the high entanglement of spins, a key ingredient for high-temperature superconductivity as suggested by physicist P. W. Anderson.
