Point Contacts

Nanoscale electrical contacts are convenient tools for the realization of local injection and detection of conduction electrons in experimental studies of electron kinetics in metals [1-6]. Recently, such point contacts have received an increased amount of attention due to their ability to produce extremely high current densities needed in spin-transfer torque (STT) experiments described on this website. Two standard types of point contacts are mechanical and lithographic, each with their own advantages. Mechanical contacts, made by gently pressing a metal wire tip onto a sample surface, are relatively simple to make and can be used on samples of arbitrary composition and shape; whereas lithographic techniques offer much greater control of contact geometry and placement, in addition to being more stable and robust, e.g., to temperature variations.

Here we describe a novel technique for point-contact fabrication, which combine the best of mechanical and lithographic techniques:

Fabrication of point contacts by FIB patterning and exploiting the contacts in transverse electron focusing (TEF) experiments to measure the relaxation time of conduction electrons in Bi

While patterned contacts are robust in experiments, mechanical contacts can be made an order of magnitude smaller in size. Here we describe how such point contacts can be used to induce and control the exchange bias on a nanoscale:

Current-induced reorientation of exchange bias on a nanoscale and effect of current-mediated STT on the strength of exchange bias

1. Sharvin, Yu. V., Sov. Phys. JETP 21, 655 (1965).

2. Tsoi, V. S., JETP Lett. 19, 70 (1974).

3. Yanson, I. K., Sov. Phys. JETP 39, 506 (1974).

4. Jansen, A. G. M., van Gelder, A. P., Wyder, P., J. Phys. C 13, 6073 (1980).

5. Tsoi, V. S., Bass, J., Wyder, P., Rev. Mod. Phys. 71, 1641 (1999).

6. Naidyuk, Yu. G., Yanson, I. K., Point-contact spectroscopy (Springer, New-York, 2004).

Supported in part by NSF grant DMR-06-45377