Using 75T Pulsed Magnetic Fields to Detect Chern Pockets With Large Orbital Moments in CsV3Sb5

What did scientists discover?

A newly discovered metal, CsV₃Sb₅, has been studied in pulsed magnetic fields of up to 75T. The experiment recorded the electrical conductivity of CsV₃Sb₅ via its effect on the frequency f of a proximal oscillator. For each field pulse, a tiny crystal of CsV₃Sb₅ was rotated to different precise angles (Figure; the angles are indicated to the right). Wiggles are seen in the frequency, and their amplitude varies with the crystal’s angle in a distinctive way.

Why is this important?

The angular variation of the wiggles is due to the presence of Chern pockets in CsV₃Sb₅. Without any external energy being supplied, Chern pockets generate circulating currents that act like tiny coils, each producing a magnetic field. Chern pockets are a key indicator of a quantum mechanical property known as topology. However, it is almost impossible to detect them, because ones with oppositely circulating currents pair up, cancelling out their magnetic fields. In this work, the problem is overcome by using high fields to generate the characteristic wiggles. This is an important measurement, because topology promises to be invaluable in future electronic devices that will work on completely new quantum principles.

Who did the research?

Kuan-Wen Chen¹, Guoxin Zheng¹, Dechen Zhang¹, Aaron Chan¹, Yuan Zhu¹, Kaila Jenkins¹, Fanghang Yu², Mengzhu Shi², Jianjun Ying², Ziji Xiang^1,2, Xianhui Chen², Ziqiang Wang³, John Singleton⁴ & Lu Li¹

¹Department of Physics, University of Michigan, ²CAS Key Laboratory of Strongly-coupled Quantum Matter Physics, ³Department of Physics, Boston College, ⁴National MagLab at Los Alamos National Laboratory

Why did they need the MagLab?

Measuring conductivity in high fields is the most reliable way of detecting consequences of topology such as the wiggles seen here. Characterizing the wiggles needs a precise knowledge of the crystal’s angle in the field, which required a special 3D printed rotator only available at the MagLab. At larger angles, the wiggles are pushed to higher fields, and so many magnet pulses up to 75T are essential to do a complete characterization.

Details for scientists

• View or download the expert-level Science Highlight, Using 75T Pulsed Magnetic Fields to Detect Chern Pockets With Large Orbital Moments in CsV₃Sb₅
• Read the full-length publication, Magnetic breakdown and spin-zero effect in quantum oscillations in kagome metal CsV₃Sb₅, in Communications Materials

Funding

This research was funded by the following grants: G.S. Boebinger (NSF DMR-2128556); J. Singleton (DOE Science of 100 T); Lu Li (DOE DE-SC0020184; NSF DMR1707620 and 2004288)

For more information, contact John Singleton.