On November 12, Physical Review B published online the collaborative research results of Professor Jin Kui from the Institute of Physics, Chinese Academy of Sciences, a user of the National Pulsed High Magnetic Field Science Center, and Nankai University. The paper is titled "Correlation between H-linear magnetoresistance and T-linear resistivity in the strange-metal state". Relying on the Pulsed High Magnetic Field Facility, this research made significant progress in studying the strange-metal state of high-temperature superconductors, revealing for the first time a universal relationship between linear magnetoresistance and linear resistivity across different high-temperature superconducting systems. Associate Professor Yang Ming from the Center provided crucial high magnetic field scientific measurements.

The normal-state resistivity of high-temperature superconductors exhibits a linear temperature dependence over a wide temperature range, known as the "strange-metal state." This phenomenon is considered a crucial breakthrough point for understanding the mechanism of high-temperature superconductivity. In recent years, experiments have discovered that within the strange-metal state, magnetoresistance also exhibits a linear dependence on the magnetic field, distinctly different from the quadratic behavior in conventional metals. Although both linear resistivity and linear magnetoresistance have been observed in various high-temperature superconducting materials, the intrinsic connection between them remains unclear, hindering a deeper understanding of the microscopic mechanism of the strange-metal state.

Addressing this issue, the research team selected triple-layer copper oxide Tl₂Ba₂Ca₂Cu₃O₁₀₊δ films with a superconducting transition temperature of 118 K and conducted systematic high-field electrical transport measurements using pulsed high magnetic fields up to 55 T. The study found that at low temperatures and under high magnetic fields, the normal-state resistivity of this material not only varies linearly with temperature but also exhibits a significant linear dependence on the magnetic field. As the temperature increases, the linear magnetoresistance gradually transitions to quadratic behavior, a change commonly observed in different types of high-temperature superconducting materials. Furthermore, by extracting the linear resistivity coefficient α and the linear magnetoresistance coefficient β from various copper-based and iron-based superconductors, it was discovered that although these materials differ significantly in lattice structure, Fermi surface, and superconducting transition temperature, their dimensionless ratio β/α falls within the same order of magnitude (average 0.40 ± 0.22). This finding suggests that the linear-in-temperature resistivity and linear-in-field magnetoresistance may originate from a common physical mechanism. Combining Boltzmann transport theory for simulation and analysis of magnetoresistance, the research team proposed that momentum-dependent anisotropic scattering might be the origin of the linear magnetoresistance observed in different high-temperature superconducting materials. This mechanism is also closely related to the electron pairing in high-temperature superconductivity.

Behavior of resistivity versus magnetic field at different temperatures for the copper oxide Tl-2223, showing strong dependence on temperature and magnetic field strength, exhibiting characteristics of the transition from linear magnetoresistance at low temperatures to quadratic magnetoresistance at high temperatures.

This research utilized the high-field, variable-temperature transport measurement conditions provided by the Pulsed High Magnetic Field Facility to establish, for the first time, a universal relationship between linear magnetoresistance and linear resistivity. This key experimental data directly reveals the synergistic regulatory effect of temperature and magnetic field on the electronic transport in high-temperature superconductors, providing important evidence for elucidating the nature of the strange-metal state.

Paper link: https://journals.aps.org/prb/abstract/10.1103/zlqq-zf1b