Wyniki wyszukiwania - BazTech

Ograniczanie wyników

2 Materials Science Poland

2 2007

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: ferromagnetic single-electron

Sortuj według:

Ogranicz wyniki do:

Electronic transport in a ferromagnetic single-electron transistor with non-collinear magnetizations in the co-tunnelling regime

Wiśniewska J., Barnaś J.

Materials Science Poland

2007

Vol. 25, No. 2

467--472

Spin-dependent electronic transport in a ferromagnetic single-electron transistor (FM SET) is studied theoretically in the Coulomb blockade regime [1]. Two external electrodes and the central part (island) of the device are assumed to be ferromagnetic, with the corresponding magnetizations being non-collinear in a general case. First order (sequential) transport is suppressed in the Coulomb blockade regime, so the second order (co-tunnelling) processes give the dominant contribution to the current. The co-tunnelling processes take place via four intermediate (virtual) states of the island: two of them are with one extra electron on the central electrode of the device (in the spin-majority or spin-minority subbands), whereas the other two virtual states are with a hole (in the spin-majority or spin-minority subbands) in the central electrode. The co-tunnelling processes create electron-hole excitations of the central electrode, and in a general case they also can create spin excitations. However, we assume relatively fast spin relaxation in the island, hence the spin accumulation is neglected. Basic transport characteristics, like tunnelling current and tunnel magnetoresistance are calculated for an arbitrary magnetic configuration of the system.

Current-induced torque in ferromagnetic single-electron devices in the limits of the fast and slow spin relaxation

Kowalik M., Weymann I., Barnaś J.

Materials Science Poland

2007

Vol. 25, No. 2

453--458

Theoretical analysis of the spin-transfer torque acting on the magnetic moment of the central electrode (island) in a single-electron ferromagnetic transistor has been performed for the spin relaxation time in the island ranging from fast to slow spin relaxation limits. The magnetic configuration of the system can be generally arbitrary. Spin accumulation on the island, due to the spin asymmetry of tunnelling processes, is taken into account. Electric current flowing through the device is calculated in the regime of sequential transport, and the master equation is used to calculate probabilities of different charge and spin states in the island. The torque acting on the central electrode is then calculated from the spin current absorbed by magnetic moment of the island.