Magnetic Signals Reveal Exotic 'Spin Liquid' State in Unusual Crystal Pattern

Published May 22, 2025

Tiny crystals of a copper-based compound, attached to a microscopic trampoline-like sensor (0.1 mm × 0.1 mm), exhibit subtle mechanical vibrations when placed in extremely strong magnetic fields (up to 75 T) and cooled to temperatures just above absolute zero. These vibrations reveal the presence of a long-predicted quantum state known as a spin-liquid, in which electrons appear to fractionalize into separate particles—one carrying electric charge and another carrying magnetic spin.

What is the finding

Magnetization measurements show that a special material called YCOB may be a quantum spin liquid—a rare and fascinating state of matter. In YCOB, copper atoms are arranged in a pattern similar to traditional Japanese basket weaving (called "kagome"). Normally, the magnetic parts of these atoms (spins) would align opposite each other, but the triangle pattern makes that impossible. Instead, the spins constantly shift around, similar to how water molecules move in liquid. In this state, the electron seems to split into two parts: one carrying its magnetism (called a spinon) and the other carrying its electric charge (a holon). These experiments show clear signs that spinons are present.

Why is this important?

Scientists have been searching for quantum spin liquids for decades; YCOB appears to be the first strong candidate. The splitting of electrons into holons and spinons (spin-charge separation) is also a rare and sought-after phenomenon, with possible applications in future quantum devices.

Who did the research?

G. Zheng¹, Y. Zhu¹, K. Chen¹, B. Kang², D. Zhang¹, K. Jenkins¹, A. Chan¹, Z. Zeng^3,4, A. Xu^3,4, O. Valenzuela⁵, J. Blawat⁵, J. Singleton⁵, S. Li^3,4,6, P. Lee² & Lu Li¹

¹Department of Physics, University of Michigan; ²Department of Physics, MIT; ³Beijing National Laboratory for Condensed Matter Physics; ⁴Physical Sciences, University of CAS; ⁵National MagLab, Los Alamos; ⁶Songshan Lake Materials Laboratory

Why did they need the MagLab?

These discoveries were only possible using the extremely powerful magnets available at the MagLab. To prove that YCOB is a quantum spin liquid, scientists looked at how its magnetization behaved in strong magnetic fields—up to 75 tesla, the highest in the U.S. They saw flat areas in the data, a sign of the quantum spin liquid state. They also used a technique called torque magnetometry, which measures how the crystals twist in the magnetic field. Small “wiggles” in this twisting showed up at specific field strengths, angles, and temperatures—clear evidence of spinons. These measurements required a special tool built through a partnership between the MagLab and industry.

Details for scientists

View or download the expert-level Science Highlight, Magnetic oscillations due to spinons in a quantum spin liquid hosted by a Kagome lattice
Read the full-length publication, Unconventional magnetic oscillations in a kagome Mott insulator, in Proc. National Academy of Sciences (PNAS)

Funding

This research was funded by the following grants:USA: NSF DMR-2128556; DOE BES; Gordon & Betty Moore Fdn; China: 2022YFA1403400, 2021YFA1400401, GJTD-2020-01, XDB33000000

For more information, contact Neil Harrison.