Synopsis: Magnetoresistance That Doesn’t Stop

A near perfect balance between electrons and holes explains why WTe2’s huge magnetoresistence doesn’t saturate at high fields, reaching 13 million percent at 60 tesla.
Synopsis figure
I. Pletikosić et al., Phys. Rev. Lett. (2014)

The change in a material’s resistance in an applied magnetic field—magnetoresistance—can be minute or colossal. But in all its forms, the effect, which is used in hard-disk drives and magnetic-field sensors, tapers off at a sufficiently high field. Tungsten ditelluride (WTe2) is the first known exception: at 0.53 kelvin, its resistance rises rapidly with increasing field, changing by 13 million percent at 60 tesla with no sign of leveling off (M. N. Ali et al., Nature 514, 205 (2014)). New photoemission experiments suggest that this effect is the result of an unusually perfect balance between electrons and holes—a finding that could suggest a route to engineer other materials with large magnetoresistance.

WTe2 has only a small number of conducting electrons and holes, and in similar concentrations. It is also “clean,” meaning the electrons and holes can travel a long distance before scattering. Metal theory predicts that materials with these properties have a resistance that increases with the square of the magnetic field. But in real materials, like bismuth and graphite, this rise stops at high fields because the electron and hole concentrations aren’t exactly the same. Ivo Pletikosić, now at Princeton University in New Jersey, and his colleagues at Brookhaven National Laboratory, New York, studied WTe2’s electronic structure with high-resolution photoemission and showed that electron-hole compensation is close to perfect. They also found that certain electron states start to dominate over holes at higher temperatures, perhaps explaining why magnetoresistance in WTe2 turns off above 100 kelvin. With a detailed mapping of WTe2’s electronic structure in hand, researchers have a reference point for understanding how doping the material could further improve its magnetoresistive properties.

This research is published in Physical Review Letters.

–Jessica Thomas


More Features »


More Announcements »

Subject Areas

MagnetismMaterials Science

Previous Synopsis

Quantum Information

Quantum Search Gets an Update

Read More »

Next Synopsis

Fluid Dynamics

Beer Forms Sudsy Surprise

Read More »

Related Articles

Viewpoint: Pushing Towards Room-Temperature Superconductivity
Condensed Matter Physics

Viewpoint: Pushing Towards Room-Temperature Superconductivity

Two independent studies report superconductivity at record high temperatures in hydrogen-rich materials under extreme pressure. Read More »

Focus: <i>Video</i>—Slow-Motion Footage Captures Rubber Band Ripples

Focus: Video—Slow-Motion Footage Captures Rubber Band Ripples

Videos of a moving rubber band show that the band takes on previously unpredicted wavy shapes when it is shot through the air. Read More »

Focus: A Home for Helium inside Earth
Materials Science

Focus: A Home for Helium inside Earth

Computations predict the existence of a compound that could store the primordial helium that is known to be present somewhere inside the Earth. Read More »

More Articles