K magnetoresistance

Among the [M(dmit)2]-based superconductors, a-[EDT-TTF][Ni(dmit)2] is also of DA type and has two outstanding features it is the oiJy one to contain a 1 1 molar ratio of donor and acceptor units and to exhibit superconductivity at ambient pressure. The phase is superconductive below 1.3 K under ambient pressure (Figure 4.24). a-[EDT-TTF] [Ni(dmit)2] exhibits a unique metallic behaviour with a characteristic resistivity peak at around 14 K. Magnetoresistance studies shown that the conduction mainly takes place along the Ni(dmit)2 stacks below 10 K, while both [Ni(dmit)2] and [EDT-TTF] stacks are involved above... 

The same k p scheme has been extended to the study of transport properties of CNTs. The conductivity calculated in the Boltzmann transport theory has shown a large positive magnetoresistance [18], This positive magnetoresistance has been confirmed by full quantum mechanical calculations in the case that the mean free path is much larger than the circumference length [19]. When the mean free path is short, the transport is reduced to that in a 2D graphite, which has also interesting characteristic features [20]. 

This correlation in the anomalies between the magnetization and the magnetoresistance is observed not only for (DMET)2FeBr4 but also for (EDTDM)2FeBr4 with remarkable pressure effects. By the application of pressure this sulfur-analogue salt behaves as a metal down to 1.8 K above pc 9.2 kbar, and under the pressure around pc the resistivity shows a remarkable anomaly around 4 K corresponding to... 

Fig. 5 (a) Field dependence of the intralayer magnetoresistance of (EDTDMEFeB at T 1.8 K under pressures of 5.4, 7.0, 10.3, and 17.6 kbar. (b) Calculated field dependence of the magnetoresistance under various pressures, expressed with an empirical parameter a (see text)... 

The Fermi surfaces of these salts have been studied by measuring the quantum oscillations [183] such as SdH (Shubnikov-de Haas) and dHvA and geometrical oscillations (AMRO, angle-dependent magnetoresistance oscillation) ([4], Appendix, pp 445 48). The Fermi surface of k-(ET)2Cu(NCS)2 (Fig. 14c) calculated based on the crystal structure is in good agreement with those observed data [225]. 

Ishii K, Fujiwara A, Suematsu H, Kubozono Y (2002) Ferromagnetism and giant magnetoresistance in the rare-earth fullerides Eug xSrxCgo. Phys Rev B65 134431/1-6... 

Fig. 11 Magnetoresistance curves of an LSMO/20 nm TPP/5 nm Co Junction measured at 80 K. The arrows indicate the relative magnetization orientation of LSMO (bottom arrow) and Co (top arrow) electrodes. Taken from [50] with permission...

Fig. 12 (a) Temperature dependence of the magnetoresistance for the junction shown in Fig. 10. The inset shows the corresponding junction resistance vs temperature with no applied magnetic field, (b) Magnetoresistance as a function of applied DC bias at 11 K for the same device in (a). Taken from [50] with permission...

Yuasa S, Nagahama T, Fukushima A, Suzuki Y, Ando K (2004) Giant room-temperature magnetoresistance in single-crystal Fe/MgO/Fe magnetic tunnel junctions. Nat Mater 3 868-871... 

Szulczewski G, Tokuc H, Oguz K, Coey JMD (2009) Magnetoresistance in magnetic tunnel Junctions with an organic barrier and a MgO spin filter. Appl Phys Lett 95 202506... 

Fig. 17. Magnetotransport properties of a 200-nm thick film of Ga -x Mnr As with x = 0.0S3 at 50 m K in high magnetic fields, (a) Hall resistance, which is a linear function of the magnetic field in the high-field region (inset), (b) Sheet resistance negative magnetoresistance tends to saturate in the high-field region (Omiya et al. 2000).

---