19 January 2017

Electrons at "extreme quantum limit" form new kind of state

Semi-classical picture of the trajectories of Fermi level electrons. Semi-classical picture of the trajectories of Fermi level electrons.

At high magnetic field, free-flowing particles condense into “puddles.”

What did scientists discover?

Scientists examined crystals of strontium titanate, which has the unusual property of allowing electricity to flow even though its electrons are extremely sparse and slow moving. The slow motion of the electrons makes them especially susceptible to magnetic forces. When scientists placed the crystal in an intense magnetic field and cooled it down almost to absolute zero, electrons formed a new kind of state called the extreme quantum limit (EQL). Under those special conditions, the usual "sea" of free-flowing electrons dries up into dense, isolated "puddles.”

Why is this important?

The nature of the EQL state has been debated theoretically for more than half a century. However, experiments to measure its properties have been hard to achieve because, for a typical electronic material, the magnetic field required to see this state is so high it occurs naturally only inside neutron stars. This research elucidates the properties of the EQL state, taking advantage of the man-made high magnetic fields at the National MagLab.

Who did the research?

Anand Bhattacharya1, Brian Skinner1,2, Guru Khalsa3, Alexey Suslov4

1Argonne National Lab.; 2MIT; 3NIST; 4National High Magnetic Field Lab.

Why did they need the MagLab?

The combination of very low temperatures produced by dilution refrigerators and the high magnetic field available only at the National MagLab was essential for observing the extreme quantum limit of the electron system and for precise measurements of the electron properties in this state.


This research was conducted in the 18-tesla superconducting magnet, the 35-tesla resistive magnet and the 45-tesla hybrid magnet, with dilution refrigerators, at the DC Field Facility.

Details for scientists


This research was funded by the following grants: G.S. Boebinger (NSF DMR-1157490); A. Bhattacharya & B. Skinner (DoE BES DE-AC02-06CH11357); B. Skinner (DoE BES DE-SC0001088)

For more information, contact Tim Murphy.


  • Research Area: Other Condensed Matter
  • Research Initiatives: Materials
  • Facility / Program: DC Field
  • Year: 2017
Last modified on 25 September 2017