What is the photoexcited state of K_3C_60 above T_c? · revision history

Revision 2

Accepted · core change · record

Changes against revision 1:

Title · changed
Revision 1: What is the photoexcited state of K3C60 above $T_{\mathrm{c}}$
Revision 2: What is the photoexcited state of $\mathrm{K_3C_{60}}$ above $T_{\mathrm{c}}$?
Plain · changed
Revision 1: After a mid-infrared pulse, the fulleride K3C60 shows an optical response like a superconductor at temperatures far above its normal $20\ \mathrm{K}$ transition, lasting up to nanoseconds. What state of matter this is remains unknown.
Revision 2: After a mid-infrared pulse, the fulleride $\mathrm{K_3C_{60}}$ shows an optical response like a superconductor at temperatures far above its normal $20\ \mathrm{K}$ transition, lasting up to nanoseconds. What state of matter this is remains unknown.
Precise · changed · core
Revision 1: K3C60 (equilibrium $T_{\mathrm{c}} = 20\,\mathrm{K}$) excited at mid-infrared or terahertz frequencies shows a transient gap in $\sigma_1(\omega)$ and $\sigma_2(\omega) \sim 1/\omega$ well above $T_{\mathrm{c}}$, with metastable states lasting nanoseconds at high fluence. Identify the state (transient superconductor, fluctuating pairs, high-mobility normal state, or analysis artifact) and its microscopic mechanism. Answer: a mechanism consistent with optical, transport and magnetic data.
Revision 2: $\mathrm{K_3C_{60}}$ (equilibrium $T_{\mathrm{c}} = 20\,\mathrm{K}$) excited at mid-infrared or terahertz frequencies shows a transient gap in $\sigma_1(\omega)$ and $\sigma_2(\omega) \sim 1/\omega$ well above $T_{\mathrm{c}}$, with metastable states lasting nanoseconds at high fluence. Identify the state (transient superconductor, fluctuating pairs, high-mobility normal state, or analysis artifact) and its microscopic mechanism. Answer: a mechanism consistent with optical, transport and magnetic data.
Settled by
Transient magnetic, zero-resistance and optical measurements on the same samples, explained by one microscopic model.
Kind
phenomenon
Answer type
mechanism
References
(empty)
Literature status
contested
Status note
Dodge, Lopez and Sahota (arXiv:2307.00204, 2023) argue the optical evidence comes from an analysis flaw and reflects photoenhanced carrier mobility; a 2025 field-expulsion search (De Vecchi et al., arXiv:2502.20276) set only an upper limit.
Posed since
2016

Decisions