2009 APS March Meeting
Volume 54, Number 1
Monday–Friday, March 16–20, 2009;
Pittsburgh, Pennsylvania
Session X29: Focus Session: Current Induced Dynamics in Magnetic Tunnel Junctions and Spin Waves
2:30 PM–5:18 PM,
Thursday, March 19, 2009
Room: 333
Sponsoring
Units:
GMAG DMP FIAP
Chair: Ioan Tudosa, University of California, San Diego
Abstract ID: BAPS.2009.MAR.X29.6
Abstract: X29.00006 : Voltage dependence properties of ballistic spin currents and spin transfer torques in magnetic tunnel junctions
3:30 PM–4:06 PM
Preview Abstract
Abstract
Author:
Mairbek Chshiev
(SPINTEC, CEA/CNRS, Grenoble, France / MINT Center, University of Alabama, AL, USA )
Interest in spintronics [1] has been strongly accentuated by the
discovery
of current induced magnetization switching caused by spin
transfer torque
(STT) [2]. Among the most favorable candidate systems for the
realization of
STT-based spintronic devices are epitaxial magnetic tunnel
junctions (MTJ)
[3]. Here we present a systematic study of voltage-induced STT in
MTJs and
provide an insight into the nature of its voltage behavior by
investigating
the properties of ballistic spin currents [4,5]. We demonstrate
that the
band filling has a dramatic impact on voltage dependence
properties of both
STT components, tunnel magnetoresistance (TMR) as well as on
equilibrium
interlayer exchange coupling [5]. Both in-plane (Slonczewski) and
perpendicular-to-the-plane (field-like) STT components
demonstrate a wide
range of nontrivial behavior as a function of applied voltage
[4,5]. The
explanation is given in terms of the spin and charge current
dependence on
the interplay between evanescent states in the insulator and the
Fermi
surfaces of the ferromagnetic electrodes comprising the MTJ [5]. In
particular we show that in ballistic regime the field-like torque
is an even
parity function of applied voltage while the parallel torque may
exhibit a
wide range of behavior [4,5]. Recent experiments [6] are in
agreement with
these predictions. Calculations are based on the non-equilibrium
Green
functions technique.\\[4pt]
[1] A. Fert et al, \textit{Mat. Sci. Eng. B,} \textbf{84}, 1
(2001); S. A. Wolf, \textit{Science,} \textbf{294}, 1488
(2001)\\[0pt]
[2] J. C. Slonczewski, \textit{J. Magn. Magn. Mat.} 159, L1
(1996); L. Berger, \textit{Phys. Rev. B} 54, 9353 (1996\\[0pt]
[3] W. H. Butler et al, \textit{Phys. Rev. B,} \textbf{63},
054416 (2001); J. Mathon and A. Umerski, \textit{Phys. Rev. B,}
\textbf{63}, 220403(R) (2001)\\[0pt]
[4] I. Theodonis et al, \textit{Phys. Rev. Lett.} \textbf{97},
237205 (2006)\\[0pt]
[5] M. Chshiev et al. \textit{IEEE Trans. Mag. }\textbf{44}
(11) (2008);~A. Kalitsov et al., \textit{submitted}\\[0pt]
[6] H. Kubota et al, \textit{Nature Physics} \textbf{4}, 37
(2008); J. C. Sankey et al, \textit{ibid.} \textbf{4}, 67 (2008);
A. Deac et al, \textit{ibid.} \textbf{4}, 803 (2008).
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2009.MAR.X29.6