56 research outputs found
Spin transfer torque oscillator based on asymmetric magnetic tunnel junctions
We present a study of the spin transfer torque oscillator based on
CoFeB/MgO/CoFeB asymmetric magnetic tunnel junctions. We observe microwave
precession in junctions with different thickness of the free magnetization
layer. Taking advantage of the ferromagnetic interlayer exchange coupling
between the free and reference layer in the MTJ and perpendicular interface
anisotropy in thin CoFeB electrode we demonstrate the nanometer scale device
that can generate high frequency signal without external magnetic field
applied. The amplitude of the oscillation exceeds 10 nV/Hz^0.5 at 1.5 GHz.Comment: 4 pages, 4 figures, to be submitted to Applied Physics Letter
Magnetic field sensor with voltage-tunable sensing properties
We report on a magnetic field sensor based on CoFeB/MgO/CoFeB magnetic tunnel
junctions. By taking advantage of the perpendicular magnetic anisotropy of the
CoFeB/MgO interface, the magnetization of the sensing layer is tilted
out-of-plane which results in a linear response to in-plane magnetic fields.
The application of a bias voltage across the MgO tunnel barrier of the field
sensor affects the magnetic anisotropy and thereby its sensing properties. An
increase of the maximum sensitivity and simultaneous decrease of the magnetic
field operating range by a factor of two is measured. Based on these results,
we propose a voltage-tunable sensor design that allows for active control of
the sensitivity and the operating filed range with the strength and polarity of
the applied bias voltage.Comment: 4 pages, 4 figures, lette
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