Quantum Limit Reveals Linear Magnetoresistance in 2D Massless Dirac Fermions
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The unusual electrical resistance observed in materials under strong magnetic fields, known as linear magnetoresistance, typically characterises three-dimensional materials, but recent observations have revealed this behaviour in two-dimensional systems. Xiao-Bin Qiang from State University, along with Han-Yi Xu and Ren-Jie Tong, and colleagues, now provide a comprehensive theoretical explanation for this phenomenon in two-dimensional massless Dirac fermions. Their work derives analytical expressions for electrical resistance under these conditions, successfully predicting a minimum conductivity in clean materials and, crucially, a linear relationship between resistance and magnetic field strength, aligning with experimental results. This achievement significantly advances understanding of how electrons behave in these materials under extreme magnetic fields, potentially informing the development of novel electronic devices. Linear magnetoresistance, a hallmark of three-dimensional Weyl metals, has recently been observed in two-dimensional graphene.
Scientists have now established a comprehensive theoretical understanding of this phenomenon, deriving analytical expressions that explain how graphene responds to magnetic fields. These expressions reveal that linear magnetoresistance arises from the interplay between imperfections within the material and a quantum mechanical effect known as the chiral anomaly, related to the asymmetry of particles and antiparticles. The results demonstrate that the magnitude of magnetoresistance is directly proportional to the density of these imperfections and the strength of the chiral anomaly, establishing a clear link between material properties and observable behaviour. This work provides a theoretical framework for understanding and potentially controlling magnetoresistance in two-dimensional materials, opening avenues for novel spintronic devices and advanced studies of quantum transport. Disorder and Interactions in 2D Dirac Materials This research presents a detailed investigation into the quantum transport properties of two-dimensional Dirac materials, such as graphene and topological semimetals, with a strong focus on the effects of imperfections and interactions. Scientists explored the theoretical foundations of these phenomena, including the minimum conductivity and the role of different scattering mechanisms. The work connects these transport properties to topological phases of matter and the quantum Hall effect, emphasizing the importance of considering long-range interactions, such as the Coulomb force, in accurately describing these materials. Researchers developed a comprehensive theoretical framework for understanding quantum transport, incorporating various effects and providing predictions for experimental observations.
Dirac Fermions Show Linear Magnetoresistance Response This work presents a comprehensive theoretical understanding of magnetoresistance in two-dimensional massless Dirac fermions, specifically in the quantum limit where only the lowest energy level is occupied. Scientists derived analytical expressions for magnetoresistivity, successfully recovering established results for minimum conductivity in clean systems and demonstrating a linear dependence of resistivity on magnetic field, consistent with experimental observations. The research utilizes the self-consistent Born approximation to model the effects of imperfections on electron transport, providing a detailed description of how these imperfections influence conductivity. Applying a perpendicular magnetic field introduces quantized energy states, known as Landau levels, and the researchers developed equations describing these levels and the corresponding wave functions of electrons within them. The core achievement lies in the derived expression for longitudinal conductivity, which incorporates the effects of imperfections and confirms a linear dependence of resistivity on magnetic field, aligning quantitatively with experimental data. Magnetoresistance Explained with Dirac Fermions and Potentials This work presents a comprehensive theoretical understanding of magnetoresistance in two-dimensional massless Dirac fermions within the quantum limit, achieved through a combination of linear-response theory and the self-consistent Born approximation. Researchers successfully derived analytical expressions for longitudinal magnetoresistivity, demonstrating how different imperfections influence the material’s response to magnetic fields. Specifically, the team showed that a delta-function potential results in field-independent resistivity, aligning with the known minimum conductivity of these materials, while a Gaussian potential leads to pronounced linear magnetoresistance, quantitatively matching experimental observations. These findings bridge a critical theoretical gap in understanding magnetoresistance in two-dimensional Dirac fermions, providing a framework for interpreting and predicting their behaviour in strong magnetic fields. 👉 More information 🗞 Linear magnetoresistance of two-dimensional massless Dirac fermions in the quantum limit 🧠 ArXiv: https://arxiv.org/abs/2512.13475 Tags: