JOSEPHSON-LIKE EFFECT IN A SPIN VALVE

GANG SU∗,†,‡ and MASUO SUZUKI† ∗

Department of Physics, The Graduate School of the Chinese Academy of Sciences, P.O. Box 3908, Beijing 100039, China †Department of Applied Physics, Faculty of Science, Science University of Tokyo, 1-3, Kagurazaki, Shinjuku-ku, Tokyo 162, Japan 

Received 28 May 2002

The possibility of the Josephson-like effect in a spin valve system is discussed. It is argued that in the absence of the bias voltage, the system can have dc currents flowing through the tunneling junction under certain conditions when alignments of spins in two ferromagnetic (FM) layers separated by an insulating layer, are parallel. The system may have ac currents flowing through the junction when spins in the two FM layers are tilting aligned or antialigned, this being a result quite different from the Josephson effect in superconducting junctions. In the presence of the bias voltage, the tunneling current is, in general, alternating, but for the case of antialigned spins, it contains a dc current component when the bias voltage takes a specific value (a resonant condition). The case with an ac bias voltage is also addressed. PACS Number(s): 73.40.Gk, 75.70.Cn, 73.40.Ei