TY - JOUR
T1 - Charge and spin transport in magnetic tunnel junctions
T2 - Microscopic theory
AU - Miura, Daisuke
AU - Sakuma, Akimasa
PY - 2012/5
Y1 - 2012/5
N2 - We study the charge and spin currents passing through a magnetic tunnel junction (MTJ) on the basis of a tightbinding model. The currents are evaluated perturbatively with respect to the tunnel Hamiltonian. The charge current has the form A[M 1(t) x M 1(t) 1 · M 2 + BM 1(t) · M 2, where M 1(t) and M 2 denote the directions of the magnetization in the free layer and fixed layer, respectively. The constant A vanishes when one or both layers are insulators, while the constant B disappears when both layers are insulators or the same ferromagnets. The first term in the expression for charge current represents dissipation driven by the effective electric field induced by the dynamic magnetization. In addition, from an investigation of the spin current, we obtain the microscopic expression for the enhanced Gilbert damping constant Δα. We show that Δα is proportional to the tunnel conductance and depends on the bias voltage.
AB - We study the charge and spin currents passing through a magnetic tunnel junction (MTJ) on the basis of a tightbinding model. The currents are evaluated perturbatively with respect to the tunnel Hamiltonian. The charge current has the form A[M 1(t) x M 1(t) 1 · M 2 + BM 1(t) · M 2, where M 1(t) and M 2 denote the directions of the magnetization in the free layer and fixed layer, respectively. The constant A vanishes when one or both layers are insulators, while the constant B disappears when both layers are insulators or the same ferromagnets. The first term in the expression for charge current represents dissipation driven by the effective electric field induced by the dynamic magnetization. In addition, from an investigation of the spin current, we obtain the microscopic expression for the enhanced Gilbert damping constant Δα. We show that Δα is proportional to the tunnel conductance and depends on the bias voltage.
KW - Magnetic tunnel junction
KW - Spin current
KW - Spin dynamics
KW - Spintronics
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U2 - 10.1143/JPSJ.81.054709
DO - 10.1143/JPSJ.81.054709
M3 - Article
AN - SCOPUS:84860612074
VL - 81
JO - Journal of the Physical Society of Japan
JF - Journal of the Physical Society of Japan
SN - 0031-9015
IS - 5
M1 - 054709
ER -