高温超导材料La3Ni2O7的零电阻和奇异金属行为OA

In 2023,signatures of pressure-induced high-temperature superconductivity with an onset transition at 80 K were observed in La3Ni2O7.However,the absence of zero resistance cast doubts on its superconductivity.By using a recently developed quasi-hydrostatic pressure technique based on a diamond anvil cell,our group successfully observe a sharp superconducting transition with a zero resistance below 40 K,providing a crucial evidence for establishing the existence of high-temperature superconductivity in La3Ni2O7.Furthermore,a pronounced linear-temperature dependent resistivity is observed above its superconducting transition,suggesting an unconventional nature of its superconducting pairing state. In addition to the discovery of zero resistance,our transport study also revises the pressure-temperature phase diagram of La3Ni2O7.It is found that La3Ni2O7 remains metallic under pressure and there is no evidence for a metal-insulator transition if the samples are properly handled during preparations.Upon increasing pressure,the density wave transition,observed near 130 K at ambient pressure,is quickly suppressed.At approximately 13.7 GPa,evidence for a pressure-induced structural phase transition is observed near 250 K,followed by a superconducting transition with an onset temperature at Tconset ≈ 37.5 K.Tc initially increases with the increase of pressure,reaching a maximum value of Tconset ≈ 66 K at 20.5 GPa.On the other hand,the slope A′ of the T-linear resistivity above Tc monotonically decreases with the increase of pressure,showing a relation of Tc ∝ √A′ above 20.5 GPa,which is similar to those recently observed in the cuprate superconductors.Furthermore,the inverse Hall coefficient 1/RH,derived from the Hall resistance measurements,reveals a notable increase at pressures above 15 GPa upon entering the high pressure phase,suggesting a substantial increase of the carrier concentration in the superconducting regime,which is further supported by band structure calculations. In this work,we present a brief summary of our research advances,and compare them with those observed in other nickelate superconductors.