Anomalously Wide Superconducting Phase of One-Dimensional Organic Conductor (TMTTF)₂SbF₆

Pressure Effect on Organic Conductors

“…For instance, the topics of the quantum critical phenomena were discussed in 2-4 GPa region, the highest T c -organic superconductivity [9], and 1D phase diagram of (TMTTF) 2 X were discussed in the 8-9 GPa region, where TMTTF is sulfur analog of TMTSF and is an abbreviation of tetramethyltetrathiafulvalene [10]. With these interests in the physics of the pressure region of the 3-4 GPa, a new piston cylinder cell other than the single walled BeCu cell was developed, which was the double-walled NiCrAl/BeCu cell.…”

“…2 X showing that it is connected to that of the (TMTSF) 2 X salts. Note that the superconducting T c is well above 2 K and spreading to a wide pressure region and the insulating phase varies from charge order to magnetic state [10]. This is the real system ,which can be compared with Jerome's generic phase diagram [46].…”

“…Actually, superconductivity was found in (TMTTF) 2 X salt by using diamond anvil cell around 5 GPa [47,48]. Later on, Itoi completed a very beautiful T-P phase diagram by using a cubic anvil cell as shown in Figure 3 [10]. Remarkable result was that the superconducting T c of this family was not around 1 K, but more than 2 K for (TMTSF) 2 AsF 6 and the superconductivity is widespread in pressure, and seems to have two T c peaks.…”

Achievements and Challenges in Molecular Conductors

“…Moreover, it is worth noting in Figure 1 that there are two different kinds of spin-Peierls (SP) and antiferromagnetic (AF) phases as a function of pressure. SP1 and AF1 had been understood in terms of the increase of dimensionality as pressure increases [41], while SP2 and AF2, which are apparently associated with CO [42][43][44][45], are now being proposed as resulting from the interplay between mutual Coulomb interactions within a chain and between chains, electron phonon interaction and electron hopping between chains [19]. …”

Stability of quantum critical points in the presence of competing orders

“…It has been identified in many heavy-fermion systems, [4][5][6] plausibly also in cuprates, 7 even possibly in pnictides, [8][9][10][11][12][13] and probably in organic charge-transfer salts. [14][15][16] Other examples include the nematic phase around the metamagnetic QCP in the bilayer ruthenate Sr 3 Ru 2 O 7 , [17][18][19][20] the origin of which is still under intense debate. [21][22][23][24][25] The emerging quantum paraelectric-ferroelectric phase diagram is also very reminiscent, 26,27 as is the disproportionation-superconducting phase in doped bismuthoxide superconductors.…”