Spin and lattice dynamics of the high-Tc nickelate superconductor La3Ni2O7

The mechanism of high-transition-temperature (high-Tc) superconductivity has been a long-standing question for several decades. Cuprate and iron-based superconductors are two well-known unconventional superconductor families that can shed light on the high-Tc mechanism. In both systems, superconductivity always emerges from the suppression of the antiferromagnetic order in parent compounds by carrier doping or applying high pressure. Nickelates have been proposed to be a promising material platform to search for high-Tc superconductivity due to the structure and electronic structure similarity with cuprates. However, only low-temperature superconductivity in the hole-doped infinite-layer nickelate thin films R1-xAxNiO2 (R = La, Nd, Pr and A = Sr, Ca) has been reported. Recently, we have successfully grown the powder and single-crystal samples of the bilayer nickelate La3Ni2O7 and observed superconductivity with a maximum Tc of 80 K at pressures between 14.0−43.5 Gpa. This observation makes the bilayer nickelate La3Ni2O7 to be a promising candidate of the second unconventional superconducting family with Tc above the liquid nitrogen boiling temperature. INS experiments on this newly discovered high-Tc nickelate superconductor La3Ni2O7 at ambient pressure are thus highly desired for clarifying unconventionality of the superconductivity in La3Ni2O7, which can help to solve the unconventional high-Tc superconductivity mechanism.