Ferromagnetism and insulating behavior with a logarithmic temperature dependence of resistivity in Pb10-xCux(PO4)6O

Recent claim of discovering above-room-temperature superconductivity (T-c approximate to 400 K) at ambient pressure in copper doped apatite Pb-10(PO4)(6)O has stimulated world-wide enthusiasm and impulse of motion. A lot of follow-up works have been carried out with controversial conclusions. To check whether superconductivity is really present or absent in the material, we need samples which should have a rather pure phase of Pb10-xCux(PO4)(6)O. Here we report the characterization results from the Pb10-xCux(PO4)(6)O with a fraction of about 97 wt.% inferred from the fitting to the X-ray diffraction pattern, if assuming Cu2S as the only impurity. The resistivity measurements show that it is a semiconductor characterized roughly by a ln(1/T) temperature dependence in wide temperature region without trace of superconductivity. Magnetization measurements show that it has a general ferromagnetic signal with a weak superparamagnetic background. Many grains of the sample show clear interactions with a NbFeB magnet. The detected Cu concentration is much lower than the expected nominal one. Our results show the absence of metallicity and superconductivity in Pb10-xCux(PO4)(6)O at ambient pressure, and suggest the presence of strong correlation effect.