Disorder Mediates Linear and Nonlinear Magnetotransport in TaNiSe, Exhibiting Negative Magnetoresistance at High Temperatures

Charge-density waves, periodic modulations of electron density, profoundly influence the electrical properties of materials, but understanding how disorder affects these properties remains a significant challenge. Xiaodong Sun, Jiabin Qiao, and Yuanzhe Li, along with their colleagues, investigate this interplay in the material tantalum nickel selenide. Their work reveals a strong connection between the material’s charge-density wave transition temperature, carrier density, and residual resistance, offering new insights into the formation of this unique electronic order. The team demonstrates that the material exhibits unusual magnetic responses, including a transition from positive to negative magnetoresistance, and importantly, they uncover a surprising suppression of second-order nonlinear signals alongside significant third-order nonlinear effects, suggesting a fundamental role for geometric quadrupole configurations and the influence of disorder on nonlinear electrical behaviour. These findings open new possibilities for designing materials with tailored magnetoresistive properties and exploring the interplay between topology, disorder, and electron transport.

Disorder and Nonlinear Electron Transport in 2DEG

Scientists report on disorder-mediated linear and nonlinear electron transport in two-dimensional electron gases with strong spin-orbit coupling. This research investigates how imperfections within a material dramatically alter its electrical conductivity, particularly when combined with the quantum mechanical property of electron spin. The team explores the interplay between disorder, spin-orbit coupling, and nonlinear transport, revealing novel mechanisms governing electron behaviour in these systems. Specifically, the research demonstrates how disorder induces a transition from conventional, diffusive transport to a unique, first-order nonlinear response, alongside enhanced higher-order nonlinear effects.

The calculations consider various levels of disorder and magnetic field strengths to map out the resulting transport properties. By analysing the current-voltage characteristics, the researchers identify the key mechanisms responsible for the observed nonlinearities. The results show that disorder not only modifies the magnitude of nonlinearities but also fundamentally alters their origin, shifting from conventional mechanisms to a new, disorder-driven process. This understanding is crucial for developing novel electronic devices that exploit nonlinear transport phenomena for applications in sensing, signal processing, and energy harvesting.

Charge-Density Wave Transition and Disorder Relationship

Scientists have uncovered a direct relationship between the charge-density-wave transition temperature, carrier density, and residual resistance ratio in tantalum nickel selenide, a complex material with potential for novel electronic applications. This connection suggests that disorder plays a crucial role in modulating the charge-density-wave transition. The team measured first-harmonic magnetoresistance, observing a negative response under a magnetic field. This negative magnetoresistance likely arises from the anomalous velocity induced by the Berry curvature of three-dimensional topological bands.

As temperature decreases, a transition from positive to negative magnetoresistance is observed with a perpendicular magnetic field, likely due to the Zeeman effect influencing current pathways. Scaling analysis suggests the presence of a quantum geometry quadrupole, indicating a specific arrangement of electronic states, and demonstrates the modulation of disorder on third-order nonlinearity. The amplitude of the third-harmonic magnetoresistance varies significantly with decreasing charge-density-wave transition temperature, highlighting the strong influence of disorder on higher-order quantum geometry and nonlinear transport. These findings pave the way for tailoring distinct magnetoresistive phases in disordered topological materials.

Tantalum Nickel Selenide Magnetoresistance and Charge Density Waves

This research details a comprehensive investigation into the electrical and magnetic properties of tantalum nickel selenide, a material exhibiting a charge-density-wave state. Scientists discovered a strong relationship between the temperature at which this charge-density-wave state appears and both the material’s inherent disorder and the concentration of charge carriers. They demonstrated that this material exhibits a negative first-order magnetoresistance, a change in electrical resistance under a magnetic field, which arises from the unique curvature of its electronic bands. Furthermore, the study revealed that while second-order nonlinear electrical responses are suppressed, third-order responses are significant and sensitive to both magnetic field and temperature, indicating the presence of specific geometric arrangements within the material. The magnitude of this third-order response expands with increasing disorder. This work advances understanding of how disorder influences both linear and nonlinear electrical and magnetic behaviour in these materials and opens possibilities for developing field-sensitive devices based on engineered higher-order magnetoresistance.