Europhys. Lett.
Volume 67, Number 6, September 2004
Page(s) 948 - 954
Section Electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics
Published online 01 September 2004
Europhys. Lett., 67 (6), pp. 948-954 (2004)
DOI: 10.1209/epl/i2004-10159-8

Giant lasing effect in magnetic nanoconductors

A. Kadigrobov1, 2, 3, Z. Ivanov1, T. Claeson1, R. I. Shekhter2 and M. Jonson2

1  Department of Microelectronics and Nanoscience, Chalmers University of Technology SE-412 96 Göteborg, Sweden
2  Department of Applied Physics, Chalmers University of Technology and Göteborg University - SE-412 96 Göteborg, Sweden
3  Theoretische Physik III, Ruhr-Universität Bochum - D-44780 Bochum, Germany

(Received 8 April 2004; accepted in final form 27 July 2004)

We propose a new principle for a compact solid-state laser in the 1-100 $\un{THz}$ regime. This is a frequency range where attempts to fabricate small-size lasers up to now have met severe technical problems. The proposed laser is based on a new mechanism for creating spin-flip processes in ferromagnetic conductors. The mechanism is due to the interaction of light with conduction electrons; the interaction strength, being proportional to the large exchange energy, exceeds the Zeeman interaction by orders of magnitude. On the basis of this interaction, a giant lasing effect is predicted in a system where a population inversion has been created by tunneling injection of spin-polarized electrons from one ferromagnetic conductor to another -the magnetization of the two ferromagnets having different orientations. Using experimental data for ferromagnetic manganese perovskites with nearly 100% spin polarization, we show the laser frequency to be in the range 1-100 $\un{THz}$. The optical gain is estimated to be of order 107 $\un{cm^{-1}}$, which exceeds the gain of conventional semiconductor lasers by 3 or 4 orders of magnitude. A relevant experimental study is proposed and discussed.

42.55.Ah - General laser theory.
42.55.Rz - Doped-insulator lasers and other solid state lasers.
73.63.Rt - Nanoscale contacts.

© EDP Sciences 2004