- Recognized for the world’s first experimental observation of a quantum spin nematic phase, validating a long-standing theoretical prediction

The Ministry of Science and ICT (Minister Yoo Sang-im, hereinafter “MSIT”) and the National Research Foundation of Korea (President Lee Kwang-bok, hereinafter “NRF”) announced that Professor Bumjoon Kim of the Department of Physics at Pohang University of Science and Technology (POSTECH) has been named the December recipient of the Scientist of the Month Award.

The Scientist of the Month Award is presented each month to an outstanding researcher who has made significant contributions to the advancement of science and technology through exceptional research and development achievements. The award includes a certificate from the MSIT Minister and a cash prize of KRW 10 million.

Professor Kim was honored for his groundbreaking achievement in experimentally observing the spin* nematic phase in the quantum material iridate (Sr₂IrO₄)** for the first time globally. This breakthrough advances the potential for future innovative technologies, such as quantum computing and high-temperature superconductors.

*Spin: In quantum mechanics, the intrinsic angular momentum of particles, akin to tiny magnets at the atomic scale.

**Iridate (Sr₂IrO₄): A compound consisting of iridium (atomic number 77), a transition metal located to the left of platinum on the periodic table, combined with oxygen. Iridates often display unusual magnetic properties.

While most materials exist in one of three phases—solid, liquid, or gas—a nematic phase, such as that found in liquid crystals* used in smartphone displays, exhibits properties of both liquids and solids.

*Liquid Crystal (LC): A unique state of matter where molecules move freely like in a liquid but maintain a regular arrangement like in a crystal.

The existence of the spin nematic phase, a phenomenon rooted in quantum mechanics, was theoretically predicted over 50 years ago. However, it remained experimentally unobserved due to the nematic phase's loss of magnetism, which rendered it undetectable by conventional methods and instruments.

To overcome this challenge, Professor Kim developed a resonant inelastic X-ray scattering (RIXS)*—only the third of its kind globally—and installed it at the Pohang Accelerator Laboratory.

*Resonant Inelastic X-ray Scattering (RIXS): An advanced instrument that analyzes the energy of X-rays scattered by a sample, akin to how a prism separates light into its constituent wavelengths. Its high resolution enables the detection of subtle wavelength differences.

Using this state-of-the-art instrument, Professor Kim successfully identified the quantum spin nematic phase in iridates, a promising candidate material for high-temperature superconductors. This marked the first-ever observation of this phase worldwide.

Moreover, he fully elucidated the spatial structure of spins within iridates and uncovered quantum entanglement among multiple spins.

Previously, high-temperature superconductivity was believed to arise only in spin liquid phases. However, by demonstrating quantum entanglement in the spin nematic phase, Professor Kim’s research suggests the possibility of high-temperature superconductivity within iridates. The findings were published in the December 2023 online edition of the prestigious journal Nature.

Professor Kim remarked, “This research is significant because it experimentally confirms the existence of the spin nematic phase, a phenomenon theorized over half a century ago. A deeper understanding of the properties of this phase could unlock new applications in high-temperature superconductors and beyond.”

For further information, please contact the Public Relations Division (Phone: +82-44-202-4034, E-mail: msitmedia@korea.kr) of the Ministry of Science and ICT. 

Please refer to the attached PDF.