[Paper Review] Materials and possible mechanisms of extremely large magnetoresistance: A review

Niu, Rui, Zhu, W. K.|arXiv (Cornell University)|Oct 20, 2021

Chemical and Physical Properties of Materials46 citations

TL;DR

This review synthesizes the current understanding of extremely large magnetoresistance (XMR) in metals and semimetals, identifying electron-hole compensation and high carrier mobility as primary mechanisms. It highlights the role of topological semimetals—especially Weyl and Dirac materials like WTe2 and TaAs—in enabling XMR values exceeding 10^8% that remain unsaturated under high magnetic fields, with implications for low-power spintronic and quantum devices.

ABSTRACT

Magnetoresistance (MR) is a characteristic that the resistance of a substance changes with the external magnetic field, reflecting various physical origins and microstructures of the substance. A large MR, namely a huge response to a low external field, has always been a useful functional feature in industrial technology and a core goal pursued by physicists and materials scientists. Conventional large MR materials are mainly manganites, whose colossal MR (CMR) can be as high as -90%. The dominant mechanism is attributed to spin configuration aligned by the external field, which reduces magnetic scattering and thus resistance. In recent years, some new systems have shown an extremely large unsaturated MR (XMR). Unlike ordinary metals, the positive MR of these systems can reach 103-108% and is persistent under super high magnetic fields. The XMR materials are mainly metals or semimetals, distributed in high-mobility topological or non-topological systems, and some are magnetic, which suggests a wide range of application scenarios. Various mechanisms have been proposed for the potential physical origin of XMR, including electron-hole compensation, steep band, ultrahigh mobility, high residual resistance ratio, topological fermions, etc. It turns out that some mechanisms play a leading role in certain systems, while more are far from clearly defined. In addition, the researches on XMR are largely overlapped or closely correlated with other recently rising physics and materials researches, such as topological matters and two-dimensional (2D) materials, which makes elucidating the mechanism of XMR even more important. Moreover, the disclosed novel properties will lay a broad and solid foundation for the design and development of functional devices. In this review, we will discuss several aspects in the following order: ...

Motivation & Objective

• To systematically review the materials and physical mechanisms underlying extremely large magnetoresistance (XMR).
• To clarify the role of electron-hole compensation, high mobility, and topological band structures in enabling XMR.
• To examine the interplay between XMR and emerging fields such as 2D materials and topological quantum matter.
• To identify open challenges and future research directions for practical device integration.

Proposed method

• Systematic classification of XMR materials by chemical composition: elemental, binary (e.g., XP, XBi, TMDs), and ternary compounds (e.g., ZrSiS, Co3Sn2S2).
• Analysis of experimental transport data, including longitudinal and transverse magnetoresistance, angular dependence, and quantum oscillations.
• Use of angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling spectroscopy to probe electronic structure and Fermi arcs.
• Theoretical modeling of band structures, including Weyl points and nodal lines, to correlate topology with XMR.
• Comparison of XMR behavior across materials with varying residual resistance ratio (RRR), carrier concentration, and effective mass.
• Evaluation of chiral anomaly effects via negative longitudinal magnetoresistance as a signature of topological Weyl semimetals.

Experimental results

Research questions

• RQ1 What physical mechanisms underlie the extreme, unsaturated magnetoresistance in non-magnetic metals and semimetals?
• RQ2 Why do certain topological semimetals like WTe2 and TaAs exhibit XMR values exceeding 10^8% without saturation?
• RQ3 How do electron-hole compensation and high carrier mobility jointly contribute to XMR?
• RQ4 To what extent do 2D and van der Waals heterostructures modify XMR behavior?
• RQ5 Why does graphene, despite hosting high mobility and Dirac fermions, show only moderate MR (~200%)?

Key findings

• XMR values as high as 2 × 10^8% were observed in WP2 at 2.5 K and 63 T, attributed to electron-hole compensation, high mobility, and an extremely high residual resistance ratio (RRR).
• WTe2 exhibits unsaturated XMR up to 60 T, with negative longitudinal magnetoresistance confirming its type II Weyl semimetal nature via chiral anomaly.
• ARPES measurements confirmed the presence of linear band dispersions and Fermi arcs in Co3Sn2S2, supporting its classification as a magnetic Weyl semimetal.
• ZrSiS and ZrSiSe exhibit ultrahigh mobility and quantum oscillations, indicating Dirac-like quasiparticles and potential for XMR.
• The XMR in layered materials like WTe2 and Cd3As2 nanosheets is strongly thickness-dependent, suggesting quantum confinement effects.
• Despite high mobility and Dirac-like features, graphene exhibits only ~200% MR, indicating that additional factors such as band structure details or scattering mechanisms limit XMR in this system.