[Paper Review] Observation of chiral magneto-transport in RPtBi topological Heusler compounds

Chandra Shekhar, Ajaya K. Nayak+15 more|arXiv (Cornell University)|Apr 6, 2016

Topological Materials and Phenomena38 references10 citations

TL;DR

This study reports the observation of chiral magneto-transport in RPtBi (R = rare earth) topological Heusler compounds, demonstrating chiral anomaly-driven negative magnetoresistance via angle-resolved quantum oscillation measurements and transport anisotropy. The key finding is the clear evidence of chiral fermions in a bulk material system, confirmed by robust negative magnetoresistance and chiral Landau level splitting under high magnetic fields.

ABSTRACT

Observation of chiral magneto-transport in RPtBi topological Heusler compounds Chandra Shekhar, Ajaya K. Nayak, Sanjay Singh, Nitesh Kumar, Shu-Chun Wu, Yang Zhang, Alexander C. Komarek, Erik Kampert, Yurii Skourski, Jochen Wosnitza, Walter Schnelle, Alix McCollam, Uli Zeitler, Jurgen Kubler, S. S. P. Parkin, Binghai Yan, C. Felser Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany Max Planck Institute of Microstructure Physics, 06120 Halle, Germany Leibniz-Institut fur Festkorperund Werkstoffforschung 01069 Dresden, Germany Dresden High Magnetic Field Laboratory (HLD-EMFL), Helmholtz-Zentrum DresdenRossendorf, 01328 Dresden, Germany High Field Magnet Laboratory (HFML EMFL), Radboud University, Toernooiveld 7, 6525 ED, Nijmegen, The Netherlands. Institut fur Festkorperphysik, Technische Universitat Darmstadt, 64289 Darmstadt, Germany Institute of Condensed Matter Physics and Photon Science, ShanghaiTech University, Shanghai 200031, China Max Planck Institute for the Physics of Complex Systems, 01187 Dresden, Germany

Motivation & Objective

• To investigate the presence of chiral fermions in RPtBi topological Heusler compounds through transport measurements.
• To determine whether chiral anomaly effects manifest in bulk RPtBi materials under high magnetic fields.
• To explore the anisotropic transport response and quantum oscillations indicative of chiral fermion behavior.
• To establish a link between electronic structure topology and observable magneto-transport phenomena in Heusler compounds.
• To provide experimental evidence of chiral fermions in a bulk crystalline system with high structural and electronic stability.

Proposed method

• Conducting high-precision electrical transport measurements in high magnetic fields up to 35 T at low temperatures (down to 20 mK).
• Measuring angular dependence of magnetoresistance to probe chiral anomaly and Landau level splitting.
• Performing angle-resolved de Haeser oscillation (Shubnikov–de Haas) measurements to extract Fermi surface topology.
• Analyzing the chiral anomaly via negative magnetoresistance and its dependence on field orientation.
• Using first-principles calculations to correlate observed transport anisotropy with electronic band structure.
• Comparing experimental results with theoretical predictions of chiral fermion states in Heusler compounds.

Experimental results

Research questions

• RQ1 Do RPtBi Heusler compounds exhibit chiral magneto-transport signatures consistent with the chiral anomaly?
• RQ2 What is the angular dependence of magnetoresistance in RPtBi, and how does it reflect chiral fermion behavior?
• RQ3 Can quantum oscillation measurements resolve the chiral Landau level splitting in these materials?
• RQ4 How does the electronic band structure of RPtBi support the existence of chiral fermions?
• RQ5 What is the role of crystal symmetry and spin-orbit coupling in stabilizing chiral fermion states in RPtBi?

Key findings

• Clear negative magnetoresistance was observed in RPtBi under high magnetic fields, indicating the chiral anomaly effect.
• The magnetoresistance anisotropy showed strong dependence on field orientation, consistent with chiral fermion transport.
• Quantum oscillation measurements revealed a Fermi surface with a large effective mass and evidence of chiral Landau level splitting.
• Angle-resolved transport data demonstrated a pronounced asymmetry in magnetoresistance for different field tilts, supporting chiral fermion behavior.
• First-principles calculations confirmed the presence of type-II Weyl fermions and chiral fermion states near the Fermi level.
• The observed chiral anomaly was robust across multiple RPtBi samples, indicating intrinsic bulk electronic response.