Gigantic Photoresponse in ¼-Filled-Band Organic Salt (EDO-TTF) ₂ PF ₆

Abstract

We report that the organic salt (EDO-TTF)2PF6 with 3/4-filled-band (1/4-filled in terms of holes), which forms an organic metal with strong electron and lattice correlation, shows a highly sensitive response to photoexcitation. An ultrafast, photoinduced phase transition from the insulator phase to the metal phase can be induced with very weak excitation intensity at near room temperature. This response makes the material attractive for applications in switching devices with room-temperature operation. The observed photo-induced spectroscopic change shows that this photoinduced phase transition process is caused by the cooperative melting of charge ordering assisted by coherent phonon generation.

Optical freezing of charge motion in an organic conductor

“…1a) in Mott insulators [4][5][6][7][8][9][10] , chargeordered (CO) systems [11][12][13][14] and charge/spin density wave materials 6,[15][16][17][18][19][20] . Recently, the excitation of coherent phonons has been established as a leading strategy for the melting/ constructing of electronic orders 8,9,[15][16][17][18][19][20] .…”

Aperiodic Spin State Ordering of Bistable Molecules and Its Photoinduced Erasing

“…The control of the functionality of a material requires understanding the complex organization of its atomic or electronic constituents, but also understanding the bi-stable or multi-stable processes addressable by external stimulation, including light for the photo-control 1,2,3,4 . On the one hand, macroscopic ordering is manifested by the appearance of regular patterns, which in some cases never repeat themselves periodically in 3D space but only in a higher dimension space: this so-called aperiodicity 5,6,7 plays a central role in the structure and physical properties of materials as diverse as quasicrystals 8 , charge-density 1 and spin-density waves 9,10 , or new superconductors 11 for instance.…”

The Earliest Stage of Photoinduced Phase Transition in a Strongly Correlated Organic System Using a 10-fs Pulse

“…(EDO-TTF) 2 PF 6 is known to show gigantic reflectivity change more than 100% immediately after photoexcitation of a CT band in the (0110) charge order insulator phase [5], where the numbers in the parenthesis represent the sequence of charge on a donor molecule in a 1D column. The photoinduced state at around 100 fs was assigned to the (1010) photoinduced original phase by measuring the transient reflectivity spectrum ranging from 18 m to 590 nm using a 120-fs pulse [6].…”