Spin Transfer in an Antiferromagnet

 

PAPER:      Z. Wei, A. Sharma, A. S. Nunez, P. M. Haney, R. A. Duine, J. Bass, A. H. MacDonald, and M. Tsoi,   Changing Exchange Bias in Spin Valves with an Electric Current,    Phys. Rev. Lett. 98, 116603 (2007)

 

PREPRINT:  Wei, Z., Sharma, A., Nunez, A. S., Haney, P. M., Duine, R. A., Bass, J., MacDonald, A. H., and Tsoi, M. Spin transfer in an antiferromagnet. Preprint cond-mat/0606462

 

SLIDES:       French-US Workshop on Spintronics

                        Saint Pierre de Chartreuse, France, June 12-13, 2006

 

ABSTRACT:

 

An electrical current can transfer spin angular momentum to a ferromagnet1-3. This novel physical phenomenon, called spin transfer, offers unprecedented spatial and temporal control over the magnetic state of a ferromagnet and has tremendous potential in a broad range of technologies, including magnetic memory and recording. Recently, it has been predicted4 that spin transfer is not limited to ferromagnets, but can also occur in antiferromagnetic materials and even be stronger under some conditions. In this paper we demonstrate transfer of spin angular momentum across an interface between ferromagnetic and antiferromagnetic metals. The spin transfer is mediated by an electrical current of high density (~1012 A/m2) and revealed by variation in the exchange bias at the ferromagnet/antiferromagnet interface. We find that, depending on the polarity of the electrical current flowing across the interface, the strength of the exchange bias can either increase or decrease. This finding is explained by the theoretical prediction that a spin polarized current generates a torque on magnetic moments in the antiferromagnet. Current-mediated variation of exchange bias can be used to control the magnetic state of spin-valve devices, e.g., in magnetic memory applications.

 

 

1.      Slonczewski, J. C. Current-driven excitation of magnetic multilayers. J. Magn. Magn. Mater. 159, L1-L7 (1996).

2.      Berger, L. Multilayer as spin-wave emitting diodes. J. Appl. Phys. 81, 4880-4882 (1997).

3.      Tsoi, M. et al. Excitation of a magnetic multilayer by an electric current. Phys. Rev. Lett. 80, 4281-4284 (1998).

4.      Núñez, A. S., Duine, R. A., Haney, P. M., and MacDonald, A. H. Theory of spin torques and giant magnetoresistance in antiferromagnetic metals. Preprint cond-mat/0510797, to appear in Phys. Rev. B.

 

 

This work was supported in part by the Welch Foundation, by DOE grant DE-FG03-02ER45958, and by NSF grants DMR-05-01013 and DMR-06-45377