Galvanomagnetic properties of air-stable and highly conductive potassium-intercalated graphite sheet

• Hall coefficient and magnetoreistance of air-stable potassium–graphite intercalation compounds derived from flexible graphite sheet were determined.
• The two-carrier model was adopted for the calculation of carrier density and mobility.
• The electron density of KC91 was estimated to be 6.4 x 1020 cm−3.
• It was comparable to the reported value (7.8×1020 cm−3) for KC48 prepared from HOPG.
• Anomaly due to phase transition was confirmed in resistivity-temperature plots.

Magnetoresistance and Hall coefficient of air-stable potassium-intercalated graphite sheets (hereafter abbreviated as K-PGS) were determined at room temperature. The magnitude of the magnetoresistance and the absolute value of Hall coefficient of K-PGS decreased with increasing potassium content of K-PGS, nK/nC. Two-carrier model was used for calculating carrier density and mobility. The electron density increased with increasing nK/nC: 3.07×1020 cm−3 (nK/nC=0.005), 5.67×1020 cm−3 (nK/nC=0.008) and 6.40×1020 cm−3 (nK/nC=0.011). The value of the electron density of K-PGS with nK/nC=0.011 (nominal composition KC91) was about 80% of the reported value, 7.8×1020 cm−3, for KC48 (nK/nC=0.021) prepared from HOPG (highly oriented pyrolytic graphite). The mobility decreased with increasing nK/nC: 2.11×103 cm2 V−1 s−1 (nK/nC=0.005), 1.42×103 cm2 V−1 s−1 (nK/nC=0.008) and 1.34×103 cm2 V−1 s−1 (nK/nC=0.011). The value of the mobility of K-PGS with nK/nC=0.011 was about 60% of the reported value (2300 cm2 V−1 s−1) for KC48 prepared from HOPG.