Pressure tuning of light-induced superconductivity in K3C60

Abstract

Optical excitation at terahertz frequencies has emerged as an effective means to dynamically manipulate complex materials. In the molecular solid K3C60, short mid-infrared pulses transform the high-temperature metal into a non-equilibrium state with the optical properties of a superconductor. Here we tune this effect with hydrostatic pressure and find that the superconducting-like features gradually disappear at around 0.3 GPa. Reduction with pressure underscores the similarity with the equilibrium superconducting phase of K3C60, in which a larger electronic bandwidth induced by pressure is also detrimental for pairing. Crucially, our observation excludes alternative interpretations based on a high-mobility metallic phase. The pressure dependence also suggests that transient, incipient superconductivity occurs far above the 150 K hypothesised previously, and rather extends all the way to room temperature.

Dynamic superconductivity responses in photoexcited optical conductivity and Nernst effect

“…3(b), we plot an estimate of T photo of the low-fluence measurements by the orange square symbol, to show that TBEC and T photo agree well. The high-fluence results [20] indicate that the photo-induced effect rapidly dies away with increasing hydrostatic pressure [20], and this makes the phase diagram of A 3 C 60 system ( Fig. 6 of ref.…”

“…Included are the superconducting T c , [46][47][48], Nernst effect onset temperature T ner [47] for BEDT with Br 73% (A), 80% (B) and 100% (C), TBEC from the superfluid density estimated by MuSR [31,45] and magnetization [46] in equilibrium and by transient photo-induced optical conductivity [19], antiferromagnetic ordering temperature TAF [47,48], and the onset temperature of photo-induced superconducting responses in the lowfluence measurements of K 3 C 60 [19]. (c) shows the temperature dependence of the superfluid density in K 3 C 60 at ambient pressure derived from the imaginary part of the optical conductivity in photo-excited measurements with low fluence [19] and high fluence [20] laser intensity, compared with equilibrium measurement, kindly provided by the authors of [19] and [20]. (d) temporal change of the spectral weight of the c-axis optical conductivity () of YBCO 6.5 [14] (T c = 50 K) caused by the photo excitation.…”

Photoinduced electron-electron pairing in the extended Falicov-Kimball model

“…The recent experimental observation of photoinduced superconductivity and increase of superconducting transition temperature in some of high-T c cuprates [62][63][64] and alkali-doped fullerenes [65,66] has stimulated extensive theoretical studies of light induced superconductivity [67][68][69][70][71][72][73]. The main focus in these theoretical studies is a photoinduced state with physical properties that is already present in the corresponding equilibrium phases.…”

Dynamical Jahn‐Teller effect in the first excited

“…For example, JT effect in the first excited C 60 anion where t 1 g next lowest unoccupied molecular orbitals (NLUMOs) are populated is of fundamental importance to interpret the absorption spectra of isolated , electron transfer process of fullerene, and excitation spectra of alkali‐doped fullerides . The importance is also suggested in recently reported light‐induced superconductivity of alkali‐doped fullerides . Moreover, JT effect involving the NLUMOs must be significant in highly alkali doped and alkali‐earth/rare‐earth doped fullerides …”