• Fri. Feb 23rd, 2024

    Critical Thought

    Critical thoughts on quantum technologies

    Exploring Exotic Quantum Phenomena in Pyrochlore Iridates

    ByThemba Hadebe

    Feb 6, 2024
    Exploring Exotic Quantum Phenomena in Pyrochlore Iridates

    Introduction

    Pyrochlore iridates are a class of materials that host a unique combination of magnetic sublattices, frustrated moments, and highly correlated electrons. They are also known for exhibiting topological Weyl semimetal and axion insulator phases. In a recent study, researchers investigated the transport and magnetotransport properties of single-crystal Sm2Ir2O7, specifically focusing on the pressure-induced quantum critical point for all-in-all-out (AIAO) Ir order.

    Contrary to previous expectations, the study found that the suppression of AIAO order did not lead to metallic conduction persisting down to zero temperature. Instead, the resistivity-minimum temperature increased under further application of pressure, suggesting the presence of another mechanism leading to non-metallic behavior. However, the magnetotransport properties did track the suppression of Ir magnetism, with a strong hysteresis observed only within the AIAO phase boundary.

    Around the pressure-induced quantum critical point, a new type of electronic phase emerged. This phase was characterized by a negative magnetoresistance with small hysteresis at low temperatures and hysteresis-free positive magnetoresistance at higher temperatures. The temperature dependence of the low-temperature transport data was best described by a model consistent with a Weyl semimetal across the entire pressure range.

    Pyrochlore iridates have a rich history of yielding new physical states and insights. Their complex magnetic behavior and highly correlated electronic states make them ideal systems for studying exotic quantum phenomena. The lanthanide pyrochlore iridates, in particular, provide an excellent environment for investigating fundamental magnetism and correlated-electron physics. The interplay between the magnetic sublattices and the presence of topological properties make these materials fascinating subjects for scientific exploration.

    In conclusion, this study on Sm2Ir2O7 sheds light on the transport and magnetotransport properties of pyrochlore iridates and their unique electronic phases. By understanding the behavior of these materials under different pressures, researchers can gain valuable insights into the underlying quantum phenomena and pave the way for future advancements in the field of condensed matter physics.

    FAQ

    Q: What are pyrochlore iridates?

    A: Pyrochlore iridates are a class of materials that possess magnetic sublattices, frustrated moments, and highly correlated electrons. They also exhibit topological Weyl semimetal and axion insulator phases.

    Q: What was the focus of the recent study on Sm2Ir2O7?

    A: The recent study investigated the transport and magnetotransport properties of single-crystal Sm2Ir2O7, with a specific focus on the pressure-induced quantum critical point for all-in-all-out (AIAO) Ir order.

    Q: Did the study find metallic conduction persisting down to zero temperature when the AIAO order was suppressed?

    A: No, contrary to previous expectations, the study found that the suppression of AIAO order did not lead to metallic conduction persisting down to zero temperature. Instead, the resistivity-minimum temperature increased under further application of pressure, suggesting the presence of another mechanism leading to non-metallic behavior.

    Q: Did the magnetotransport properties track the suppression of Ir magnetism?

    A: Yes, the magnetotransport properties did track the suppression of Ir magnetism, with a strong hysteresis observed only within the AIAO phase boundary.

    Q: What type of electronic phase emerged around the pressure-induced quantum critical point?

    A: Around the pressure-induced quantum critical point, a new type of electronic phase emerged. This phase was characterized by a negative magnetoresistance with small hysteresis at low temperatures and hysteresis-free positive magnetoresistance at higher temperatures. The low-temperature transport data was best described by a Weyl semimetal model.

    Definitions

    – Pyrochlore: Refers to a crystal structure in which the metal atoms are arranged in a network of corner-sharing tetrahedra.
    – Iridates: Compounds containing the element iridium (Ir).
    – Magnetic sublattices: Different regions within a crystal lattice where magnetic moments are present.
    – Frustrated moments: Magnetic moments that are unable to achieve their lowest energy state due to competing interactions.
    – Highly correlated electrons: Electrons that strongly interact with each other, leading to emergent properties and phenomena.
    – Quantum critical point: A point in the phase diagram of a material where its physical properties undergo a dramatic change due to quantum mechanical effects.
    – Resistivity: A measure of a material’s ability to resist the flow of electric current.
    – Hysteresis: The dependence of a system’s output on its past history.
    – Weyl semimetal: A type of material that exhibits unusual electronic properties due to the presence of Weyl points, which are gapless points in the electronic band structure.

    Main Domain Links

    Nature: A renowned scientific journal that publishes research across various fields, including condensed matter physics.
    Physical Review X: An open-access journal that covers all areas of physics, including condensed matter physics.
    Physical Review B: A journal focused on condensed matter and materials physics, publishing both experimental and theoretical research.