Electric Field Control of Spin Transport

Spintronics is an approach to electronics in which the spin of the electrons is exploited to control the electric resistance R of devices. One basic building block is the spin-valve, which is formed if two ferromagnetic electrodes are separated by a thin tunneling barrier. In such devices, R depends on the orientation of the magnetisation of the electrodes. It is usually larger in the antiparallel than in the parallel configuration. The relative difference of R, the so-called magneto-resistance (MR), is then positive. Common devices, such as the giant magneto-resistance sensor used in reading heads of hard disks, are based on this phenomenon. The MR may become anomalous (negative), if the transmission probability of electrons through the device is spin or energy dependent. This offers a route to the realisation of gate-tunable MR devices, because transmission probabilities can readily be tuned in many devices with an electrical gate signal. Such devices have, however, been elusive so far. We report here on a pronounced gate-field controlled MR in devices made from carbon nanotubes with ferromagnetic contacts. Both the amplitude and the sign of the MR are tunable with the gate voltage in a predictable manner. We emphasise that this spin-field effect is not restricted to carbon nanotubes but constitutes a generic effect which can in principle be exploited in all resonant tunneling devices.Comment: 22 pages, 5 figure

Effectiveness of the ascomycin macrolactam SDZ ASM 981 in the topical treatment of atopic dermatitis

OBJECTIVE: To compare the safety and efficacy of 1% SDZ ASM 981 cream and a matching placebo cream in the treatment of patients with moderate atopic dermatitis. DESIGN: A randomized, double-blind, placebo-controlled, right-and-left comparison study. SETTING: Academic referral center. PATIENTS: Thirty-four adult patients with moderate atopic dermatitis. INTERVENTION: Topical 1% SDZ ASM 981 cream was applied twice daily (n=16) or once daily (n=18) and compared with a corresponding placebo cream base. MAIN OUTCOME MEASURES: Efficacy was measured using a 4-point (0-3) scale for erythema, pruritus, exudation, excoriation, and lichenification (Atopic Dermatitis Severity Index [ADSI]). The ADSI score was defined as the sum of these 5 ratings (range, 0-15) and was determined on the pretreatment day (1 to 14 days before day 0) and on days 0, 2, 4, 7, 9, 11, 14, 16, 18, and 21. The percentage change from baseline (day 0) in the ADSI score was calculated on each of these days. Safety was evaluated by monitoring of adverse events, physical examination, hematologic examination, clinical chemistry studies, urinalysis, and measurement of blood levels of SDZ ASM 981. RESULTS: Of the 38 patients recruited, 34 started and 28 completed treatment according to the protocol. Sixteen patients used the cream twice daily, with significant improvement after 2 days of treatment. Within 3 weeks of topical therapy with 1% SDZ ASM 981 cream twice daily, a mean reduction of 71.9% in the ADSI score was observed at the actively treated test sites compared with a mean reduction of 10.3% at the placebo-treated test sites (P <.001). Efficacy was significantly less in the group treated once daily (n=18), with mean reductions of 37.7% and 6.2%, respectively. The efficacy was especially apparent for pruritus and excoriation. There were no clinically relevant drug-related adverse effects. CONCLUSIONS: Treatment with 1% SDZ ASM 981 cream was well tolerated. Twice-daily application of 1% SDZ ASM 981 cream was significantly more effective than use of the corresponding placebo and more effective than once-daily treatment. The new macrolactam ascomycin derivative SDZ ASM 981 is a promising agent for the treatment of patients with atopic dermatitis. More elaborate phase 2 and 3 trials are under way to fully investigate the potential of this medicatio