Possible high temperature superconducting transitions in disordered graphite obtained from room temperature deintercalated KC$_8$

TL;DR

This study explores how disordered, deintercalated graphite exhibits multiple phase transitions, including potential high-temperature superconductivity, revealed through magnetization and resistivity anomalies across various samples.

Contribution

It demonstrates that induced disorder in graphite can lead to multiple phase transitions, including possible high-temperature superconductivity, expanding understanding of graphite's electronic properties.

Findings

Multiple magnetic anomalies at ~110K, ~240K, and ~320K.

Resistivity drops up to 90% at ~240K.

Disorder influences magnetic and electronic phase behavior.

Abstract

Although progress with twisted graphene nano-devices is boosting the superconductivity that is the consequence of their Moir\'e flat electronic bands, the immense choice for future development is an obstacle for their optimisation. We report here that soft-chemistry deintercalation of KC$_8$ breaks down graphite stacking generating a strong disorder that includes stacking twists and variable local doping. We obtain a bulk graphite whose individual crystallites have different stackings with arbitrary twists and doping, scanning in the same sample a huge number of stacking configurations. We perform magnetisation measurements on batches with different synthesis conditions. The disorder weakens the huge diamagnetism of graphite, revealing several phase transitions. A "ferromagnetic-like" magnetisation appears with Curie temperatures T$_0$$\sim$450K, that has to be subtracted from the measured magnetisation. Depending on sample synthesis, anomalies towards diamagnetic states appear at T$_c$$\sim$110K (3 samples), $\sim$240K (4 samples), $\sim$320K (2 samples). Electrical resistivity measurements yield anomalies for the T$_c\sim$240K transition, with one sample showing a 90% drop. We discuss the possibility that these (diamagnetic and resistitive) anomalies could be due to superconductivity.