New magnetic topological semimetal has energy-saving potential

First, some background

A fundamental building block of the standard model for particle physics is the Weyl fermion. First postulated in 1929, it has been sought after by high-energy physicists for decades without success. Recent breakthroughs in condensed matter physics have allowed the observation of Weyl fermions as quasiparticles in crystalline materials.

What did scientists discover?

Working in high magnetic fields, scientists have shown Sr_1-yMn_1-zSb₂ (y,z < 0.1) to be a Weyl material.

This new magnetic material displays electronic charge carriers that have almost no mass in any of the three directions, resulting in much faster than normal electron movement through the material. The magnetism brings with it an important symmetry-breaking property — time reversal symmetry (TRS) breaking. The combination of relativistic electron behavior and TRS breaking has been predicted to cause even more unusual behavior: the much sought-after magnetic Weyl semimetal phase.

Why is this important?

The recent discoveries of topological materials hold great promise for reducing energy consumption in electronics because they constitute a new class of quantum materials in which the current-carrying electrons can act as if they have no mass, similar to the properties of photons.

Amazingly, these electronic states are robust and immune to defects and disorder because they are protected from scattering by symmetry. This scattering is what leads to energy losses in conventional conductors like copper. The result is expected to be an increase in energy-saving efficiencies in electronic devices.

Who did the research?

J. Y. Liu¹, J. Hu¹, Q. Zhang^2,3, D. Graf⁴, H. Cao³, S. Radmanesh⁵, D. Adams⁵, Y. Zhu¹, G. Cheng^1,6, X. Liu¹,W. Phelan², J.Wei¹, M. Jaime⁷, F. Balakirev⁷, D. Tennant³, J. DiTusa², I. Chiorescu^4,8, L. Spinu⁵ and Z. Q. Mao¹

¹Tulane Univ., New Orleans, LA; ²LSU, Baton Rouge, LA; ³ORNL, Oak Ridge, TN; ⁴National MagLab, Tallahassee, FL; ⁵Univ. New Orleans, New Orleans, LA; ⁶CAS, Shangai, China; ⁷LANL, Los Alamos, NM; ⁸FSU-TLH, FL.

Why did they need the MagLab?

The high magnetic fields provided by the MagLab allowed the researchers to determine that the electrons in this material move at nearly-relativistic speeds by using the observation of quantum oscillations to determine the effective mass of the charge carriers.

Details for scientists

• View or download the expert-level Science Highlight, A magnetic topological semimetal Sr_1-yMn_1-zSb₂(y,z < 0.1)
• Read the full-length publication, A magnetic topological semimetal Sr_1−yMn_1−zSb₂ (y, z < 0.1), in Nature Materials

Funding

This research was funded by the following grants: G.S. Boebinger (NSF DMR-1157490); Z.Q. Mao (NSF DMR-1205469)

For more information, contact Tim Murphy.