Observation of diamagnetic strange-metal phase in sulfur-copper codoped lead apatite (2403.11126v3)

Abstract: By codoping sulfur and copper into lead apatite, the crystal grains are directionally stacked and the room-temperature resistivity is reduced from insulating to $2\times10^{-5}~\Omega\cdot$m. The resistance-temperature curve exhibits a nearly linear relationship at low temperature suggesting the presence of strange-metal phase, and a second-order phase transition is then observed at around 230~K during cooling the samples. A possible Meissner effect is present in dc magnetic measurements. Further hydrothermal lead-free synthesis results in smaller resistance and stronger diamagnetism, demonstrating the essential component might be sulfur-substituted copper apatite and the alkalis matter as well. A clear pathway towards superconductivity in this material is subsequently benchmarked.

• The paper demonstrates that sulfur-copper codoping transforms lead apatite into a material with a strange-metal phase and pronounced diamagnetism.
• Employing hydrothermal synthesis, the researchers achieved a resistivity reduction to 2×10⁻⁵ Ω·m and identified a second-order phase transition near 230 K.
• The study underscores reproducible tuning of electronic and magnetic properties, advancing potential pathways toward room-temperature superconductivity.

Overview of Diamagnetic Strange-Metal Phase Observations in Sulfur-Copper Codoped Lead Apatite

The paper addresses the synthesis and characterization of a potentially novel material, sulfur-copper codoped lead apatite (SCCLA), that exhibits intriguing diamagnetic and transport properties. Specifically, the authors explore the presence of a strange-metal phase in SCCLA, achieving substantial reductions in resistivity and reporting evidence suggestive of a Meissner effect. This paper provides a pathway towards understanding the interplay between materials' electronic structures and their superconducting capabilities.

The researchers employed a hydrothermal synthesis approach infused with sulfur and copper to modify lead apatite’s crystalline structure. The resultant material demonstrates a directional stacking of crystal grains, transitioning from an insulating state to possessing a resistivity on the order of $2\times10^{-5}~\Omega\cdot$m at room temperature. This marked change underscores a substantial enhancement in conductivity, which they attribute to the sulfur-copper codoping and subsequent structural transformations.

Key Findings and Numerical Results

The paper presents a notable observation of nearly linear resistivity behavior as a function of temperature at low temperatures, which is characteristic of a strange-metal phase. Furthermore, a second-order phase transition was identified around 230 K, apparent through both cooling experiments and critical temperature evaluations.

• Resistivity: The material transitions from an insulator to a resistive state akin to graphite upon doping.
• Magnetic Properties: Clear signs of diamagnetism were observed up to nearly room temperature, with magnetic hysteresis present up to 250 K, suggesting the potential onset of a Meissner effect.
• Synthesized Phases: A significant contrast in the critical transitions of SCCLA was established between different samples and conditions, reinforcing the reproducibility and tuning capabilities of synthesis methods.

Complementary studies of a lead-free alternative demonstrate even lower resistance and stronger diamagnetism, indicating that lead elements in the original material might be non-critical to the superconducting-like behavior but rather contribute to the structural integrity.

Implications and Speculations on Future Development

This research contributes to the ongoing investigation into creating high-temperature superconductors by revealing a possible association between strange-metal behavior and observable superconducting transitions. The findings pose significant theoretical implications for understanding electron correlations in low-dimensional systems, aligning with the anomalous behaviors often seen in cuprate or iron-based superconductors.

Practically, the application realms of SCCLA or its derivatives could extend across electronic and energy sectors, promoting new standards in electronic materials where conductivity at ambient conditions is desirable. The evident susceptibility of the material's properties to synthesis methods invites further exploration into compositional and structural optimizations that might refine these findings into usable technologies.

Future work might focus on more accurately characterizing the superconducting phases and exploring alternative doping strategies or compatible lattice frameworks. Integrating computational models to predict possible material behaviors can further elucidate the pathways toward achieving stable room-temperature superconductors.

In conclusion, the paper forwards our understanding of how complex material systems can host intricate phases transitional between insulative and superconductive states, with broad implications for condensed matter physics and material science.