27 June 2018

Phase diagram of URu2–xFexSi2 in high magnetic fields

Left: Three-dimensional phase diagram for URu2−x FexSi2 single crystals, with temperature T.  Right: Normalized critical-field H/H0. Left: Three-dimensional phase diagram for URu2−x FexSi2 single crystals, with temperature T. Right: Normalized critical-field H/H0.

Scientists used high magnetic fields and low temperatures to study crystals of URu2–xFexSi2. Using these conditions, they explored an intriguing state of matter called the "hidden order phase" that exhibits emergent behavior. Emergent behavior occurs when the whole is greater than the sum of its parts, meaning the whole has exciting properties that its parts do not possess; it is an important concept in philosophy, the brain and theories of life. This data provide strict constraints on theories of emergent behavior.

What did scientists discover?

MagLab users measured the resistance of single crystals of URu2–xFexSi2 for various iron (Fe) concentrations, x, in very high magnetic fields. Changes in the electrical resistance allowed the boundaries between different phases of this material system to be mapped.

Why is this important?

In philosophy, systems theory, science and art, emergence occurs when the whole is greater than the sum of the parts, meaning the whole has properties that its parts do not possess. These properties come about because of interactions among the parts. Emergence plays an increasing role in theories of complex materials. The mysterious hidden order phase of URu2Si2 is a prime example of emergence, and this experiment allowed us to map out a three-dimensional (3D) field-temperature-composition phase diagram for the first time in this compound. This work established a single relation between the transition temperature and the critical magnetic field for the hidden order (HO) phase, which imposes constraints on any theories of the HO phase and its emergent behavior.

Who did the research?

Sheng Rana,b, Inho Jeonb,c, Naveen Pousea,b, Alexander J. Breindela,b, Noravee Kanchanavateea,b, Kevin Huangb,c, Andrew Gallagherd, Kuan-Wen Chend, David Grafd, Ryan E. Baumbachd, John Singletond, and M. Brian Maplea,b,c.

aPhysics, UCSD; bCenter for Advanced Nanoscience, UCSD; cMaterials Science and Engineering, UCSD; dNational MagLab

Why did they need the MagLab?

Very high magnetic fields and cryogenic temperatures are required to access the exotic phases that exhibit emergent behavior. Special instrumentation, unique to the MagLab, was used to make sufficiently precise resistance measurements.

THE TOOLS THEY USED

This research was conducted in the 65-Tesla Multi-Shot Magnet at the Pulsed Field Facility and the 45-Tesla Hybrid Magnet at the DC Field Facility.

Details for scientists

Funding

This research was funded by the following grants: A. Gallagher, K.-W. Chen, D. Graf, R.E. Baumbach, J. Singleton (NSF DMR-1157490); N.P. Wilson, X.Xu S. Ran, I. Jeon, N. Pouse, A.J. Breindel, N. Kanchanavatee, K. Huang, M.B. Maple (DOE DE-FG02-04ER46105 and DE-NA0002909, NSF DMR-1206553)


For more information, contact Marcelo Jaime.

Details

  • Research Area: Chemistry - Materials,Kondo/Heavy Fermion Systems, Magnetism and Magnetic Materials, Other Condensed Matter, Quantum Fluids and Solids, Semiconductors, Superconductivity - Basic
  • Research Initiatives: Materials
  • Facility / Program: Pulsed Field
  • Year: 2018
Last modified on 27 June 2018