Abstract

Recent advancement in nanofabrication and growth allows the utilisation of spin-polarised electrons in transport and dynamics, resulting in the development of spintronic devices [1]. In the spintronic devices, the key technologies are injection, manipulation and detection of spin-polarised electron in a non-magnetic media with high efficiency.

Conventionally such a spin-polarised electron current has been injected into a non-magnetic material by flowing an electrical current through a ferromagnetic layer. However, its spin polarisation is dependent upon the interfacial properties, such as conductance matching, junction resistance and interfacial resonant states. We recently succeeded to fabricate an abrupt Fe/GaAs(001) interface for the first time and have demonstrated reproducible spin transport across the interface [2]. This system offers an ideal junction to form a spin-polarised field effect transistor for example.

We also demonstrated spin-current amplification in a lateral spin-valve (LSV) using a geometrical ratchet effect [3]. Two Py nanowires were designed to be 30 nm thick and 200 nm wide bridged by a Cu nanowire (70 nm thick and 100 nm wide). Here, the central part of the Cu wire was modified into the following geometrical ratchet shapes with allowing 50 nm separation between the Py wires and the ratchets. We measured over 700% spin-current amplification for the right-angled triangles with 100 nm base and 60 nm height.

By utilising these fundamental building blocks, we can also develop a large variety of new devices.

This work was partially supported by the EPSRC (EP/I000933/1 and EP/K03278X/1), Royal Society Industry Fellowship, EC (NMP3-SL-2013-604398) and JST -PRESTO.

[1] A. Hirohata and K. Takanashi, J. Phys. D: Appl. Phys. (in press). [2] L. R. Fleet et al., Phys. Rev. B 87 , 024401 (2013). [3] R. M. Abdullah et al., J. Phys. D: Appl. Phys. 47, 482001 (2014).