South Korean scientists have made a groundbreaking discovery by straight observing spin quadrupoles in a spin-nematic phase using advanced x-ray and optical methods. This accomplishment in studying Sr2IrO4 opens brand-new possibilities in quantum computing and high-temperature superconductivity research.The “spin-nematic phase,” a magnetic analog of liquid crystal, has actually been observed for the very first time in a quantum spin system.Liquid crystal represents a special state of matter, combining qualities of both liquids and solids. It has the ability to flow similarly to a liquid, yet its molecules keep a positioning comparable to that discovered in solids. The liquid crystal is extensively used nowadays, for instance, as a core component of LCD gadgets. The magnetic analog of this type of material is called the “spin-nematic stage”, where spin minutes play the role of the molecules.However, it has actually not yet been straight observed in spite of its forecast a half-century earlier. The main challenge originates from the reality that a lot of conventional experimental methods are insensitive to spin quadrupoles, which are the defining features of this spin-nematic phase.Breakthrough in Spin-Nematic Phase ObservationBut now for the very first time worldwide, a team of researchers led by Professor Kim Bumjoon at the IBS Center for Artificial Low Dimensional Electronic Systems in South Korea succeeded at straight observing spin quadrupoles. This work was enabled through amazing accomplishments over the last decades in synchrotron center development.Spin one-half minutes on a square lattice. In addition to the classical antiferromagnetic order (classical AF), the spin minutes can have various magnetic ground states, such as superposition of spin-singlet configurations (resonant valence bond; RVB) or antiferromagnet with large quantum fluctuations (quantum AF). In iridium oxide Sr2IrO4, spin quadrupole moments exist together with a canted antiferromagnet order. Credit: Institute for Basic ScienceThe IBS scientists focused their study on square-lattice iridium oxide Sr2IrO4, a material previously recognized for its antiferromagnetic dipolar order at low temperatures. This study newly found the coexistence of a spin quadrupolar order, which ends up being observable through its disturbance with the magnetic order. This interference signal was discovered by circular-dichroic resonant x-ray diffraction, an advanced x-ray method employing a circularly polarized x-ray beam.Advanced Techniques and CollaborationsFurther confirmation of this discovery came through polarization-resolved resonant inelastic x-ray scattering, where the magnetic excitations were revealed to substantially differ the habits anticipated for those inDipole-quadrupole disturbance in circular dichroic resonant x-ray diffraction. (a) The spin quadrupole moments are formed at a higher temperature level (263 K) than the magnetic minutes (230 K). (b, c) At low temperatures, the disturbance in between the spin quadrupole and the magnetic moments is manifested by circular dichroic resonant X-ray diffraction, a magnetic signal difference in between left- and right-handed X-ray beams. Credit: Institute for Basic Scienceconventional magnets. For the conclusion of these experiments, the scientists in South Korea have collaborated with Argonne National Laboratory in the United States to construct a resonant inelastic x-ray scattering beamline in Pohang Accelerator Laboratory over the last 4 years.Last but not least, the scientists used a series of optical methods, consisting of Raman spectroscopy and magneto-optical Kerr effect measurement, to reveal that the formation of the spin quadrupole moments happens at greater temperatures than the magnetic order. Within this temperature level variety, the iridium oxide has only spin quadrupole minutes but no magnetic order, recognizing a spin-nematic phase.Taken together, this is the very first direct observation of the spin quadrupole minutes in a spin-nematic phase.(a, b) Drawing (a) and photo (b) of the resonant inelastic x-ray scattering spectrometer installed at the 1C beamline of PLS-II. Credit: Institute for Basic Science”This research study was feasible since the facilities and capabilities of x-ray experiments in South Korea had actually reached an internationally competitive level,” states Prof. Kim Bumjoon, matching author of this study.”The discovery of the spin-nematic phase likewise holds substantial ramifications for quantum computing and infotech,” adds Prof. Cho Gil Young, a co-author of this study and professor at Pohang University of Science and Technology.Another intriguing element of the spin-nematic phase is its capacity for high-temperature superconductivity. In the spin-nematic phase, the spins are extremely knotted, which was suggested by physicist P. W. Anderson as a key component for high-temperature superconductivity. In addition, offered that iridium oxide Sr2IrO4 has actually been extensively studied because of its striking resemblances with the copper-oxide high-temperature superconducting system, which fuels a growing interest in this product as a potentially brand-new high-temperature superconducting system, as well as its relation to the spin-nematic phase.Reference: “Quantum spin nematic phase in a square-lattice iridate” by Hoon Kim, Jin-Kwang Kim, Junyoung Kwon, Jimin Kim, Hyun-Woo J. Kim, Seunghyeok Ha, Kwangrae Kim, Wonjun Lee, Jonghwan Kim, Gil Young Cho, Hyeokjun Heo, Joonho Jang, C. J. Sahle, A. Longo, J. Strempfer, G. Fabbris, Y. Choi, D. Haskel, Jungho Kim, J. -W. Kim and B. J. Kim, 13 December 2023, Nature.DOI: 10.1038/ s41586-023-06829-4The study was moneyed by the Institute for Basic Science.
The main challenge stems from the truth that many standard speculative techniques are insensitive to spin quadrupoles, which are the defining functions of this spin-nematic phase.Breakthrough in Spin-Nematic Phase ObservationBut now for the very first time in the world, a team of researchers led by Professor Kim Bumjoon at the IBS Center for Artificial Low Dimensional Electronic Systems in South Korea was successful at straight observing spin quadrupoles. (b, c) At low temperature levels, the disturbance in between the spin quadrupole and the magnetic moments is manifested by circular dichroic resonant X-ray diffraction, a magnetic signal difference in between left- and right-handed X-ray beams. Within this temperature variety, the iridium oxide has just spin quadrupole minutes but no magnetic order, understanding a spin-nematic phase.Taken together, this is the first direct observation of the spin quadrupole minutes in a spin-nematic stage. Given that iridium oxide Sr2IrO4 has been extensively studied because of its striking similarities with the copper-oxide high-temperature superconducting system, which fuels a growing interest in this material as a potentially brand-new high-temperature superconducting system, as well as its relation to the spin-nematic phase.Reference: “Quantum spin nematic stage in a square-lattice iridate” by Hoon Kim, Jin-Kwang Kim, Junyoung Kwon, Jimin Kim, Hyun-Woo J. Kim, Seunghyeok Ha, Kwangrae Kim, Wonjun Lee, Jonghwan Kim, Gil Young Cho, Hyeokjun Heo, Joonho Jang, C. J. Sahle, A. Longo, J. Strempfer, G. Fabbris, Y. Choi, D. Haskel, Jungho Kim, J. -W. Kim and B. J. Kim, 13 December 2023, Nature.DOI: 10.1038/ s41586-023-06829-4The research study was moneyed by the Institute for Basic Science.
