Superconductivity field-induced

The synthesis of the bis-l,3-dithiolium radical cation (TTF+) in 1970 [1] enabled dramatic growth in the field of molecular conductors in the decades thereafter. TTF and several of its homologues are depicted in Scheme 1. The field of low dimensional molecular metals was further motivated by the discovery of the TTF-TCNQ charge-transfer complex in 1973 [2, 3]. Seven years later, superconductivity was induced in the cation-radical salt, (TMTSF)2PF6, upon application of 12 kbar pressure [4]. Shortly thereafter, superconductivity below 1.4 K was observed at ambient pressure in the perchlorate analog [5]. 

Superlattices result from the periodic infinite repetition of heterostructures. MBE-grown superlattices of III-V semiconductors exhibit sharp interfaces and high carrier mobilities of the resulting 2D carrier gas at low temperature (Ando et al, 1982). To date no superconductivity has been found for such engineered solids, although some expectations were raised in 2000 after some reports on the obten-tion of superconductivity in semiconductor/insulator interfaces by field-induced... 

Balicas L, Behnia K, Kang W, Canadell E, Auban-Senzier P, Jerome D, Ribault M, Fabre JM (1994) Superconductivity and magnetic field induced spin density waves in the (TMTTF)2X family. J Phys I 4 1539-1549... 

Sushko YV, Ito H, Ishiguro T, Horiuchi S, Saito G (1993) Magnetic-field-induced transition to resistive phase in superconducting k-(BEDT-TTF)2Cu[N(CN)2]C1. J Phys Soc Jpn 62 3372-3375... 

Konoike T, Uji S, Terashima T, Nishimura M, Yasuzuka S, Enomoto K, Eujiwara H, Zhang B, Kobayashi H (2004) Magnetic-field-induced superconductivity in the antiferromagnetic organic superconductor K-(BETS)2peBr4. Phys Rev B70 094514/l-5... 

Uji S, Shinagawa H, Terashima T, Yakabe T, Terai Y, Tokumoto M, Kobayashi A, Tanaka H, Kobayashi H (2001) Magnetic-field-induced superconductivity in a two-dimensional organic conductor. Nature 410 908-910... 

Meul HW, Rossel C, Decroux M, Fischer 0, Remenyi G, Briggs A (1984) Observation of magnetic-field-induced superconductivity. Phys Rev Lett 53 497-500... 

Lin CL, Teter J, Crow JE, Mihalisin T, Brooks J, Abou-Aly AI, Stewart GR (1985) Observation of magnetic-field-induced superconductivity in a heavy-Eermion antiferro-magnet CePb3. Phys Rev Lett 54 2541-2544... 

The list of materials which displayed such type of behaviour contains amorphous Mo Gei j, [1] and Moa,Sii a [2] films, amorphous InOx films [3, 4], ultrathin films of Be [5], crystalline films of Nd2-a Cea Cu04+y [6, 7]. Two typical examples of such sets of curves relevant to different limits are presented in Figs. 1 and 2. In Nd2-a Cea Cu04+ / (Fig. 1) the growth of the resistance with decreasing temperature on the non-superconducting side of the field-induced transition was below ten percent so that it reminded more a metal with quantum corrections to its conductivity than an insulator. In amorphous InO (Fig. 2), typical for insulator exponential temperature dependence of the resistance resulted in almost tenfold increase of the resistance. 

To conclude, we have shown that the specific shape of Hc2(T) observed in the cobalt oxide superconductor can be explained in terms of the field-induced transition from singlet to triplet pairing. This scenario assumes a competition between singlet and triplet types of superconductivity, which remains in... 

In some organic conductors there is also magnetic field-induced superconductivity—for example, in /-(BETS TeCh at 17 T and 0.1 K [37], A new superconductor of picene (27) "doped" with alkali metals is reported to have TC = 18K [38]. Ca-intercalated graphite CaCf, superconducts below TC = 11.5K [39],... 

---