Rectification of radio-frequency current in a giant-magnetoresistance spin valve

Abstract

We report on a highly efficient spin diode effect in an exchange-biased spin-valve giant magnetoresistance (GMR) strips. In such multilayer structures, symmetry of the current distribution along the vertical direction is broken and, as a result, a non-compensated Oersted field acting on the magnetic free layer appears. This field, in turn, is a driving force of magnetization precessions. Due to the GMR effect, resistance of the strip oscillates following the magnetization dynamics. This leads to rectification of the applied radio frequency current and induces a direct current voltage VDC . We present a theoretical description of this phenomenon and calculate the spin diode signal, VDC , as a function of frequency, external magnetic field, and angle at which the external field is applied. A satisfactory quantitative agreement between theoretical predictions and experimental data has been achieved. Finally, we show that the spin diode signal in GMR devices is significantly stronger than in the anisotropic magnetoresistance permalloy-based devices.

Microwave detection based on magnetoresistance effect in spintronic devices

“…Frequency dependent losses of the measurement setup and DUT (originating mainly from the impedance mismatch) were taken into account [6].…”

“…In addition, the RF signal detection in case of GMR can be realized also at the frequencies below the resonance, i.e., in a much broader range, at the cost of the sensitivity. In such case, the operation of the detector is less dependent on the magnetic field [6].…”

Electric-field tunable spin waves in PMN-PT/NiFe heterostructure: Experiment and micromagnetic simulations

“…FMR spectra were measured using (SD) technique similarly to Ref. 16. An RF current of 10 dBm power at frequencies in range form 3 GHz to 8 GHz was passed trough the ferromagnetic microstrip.…”

“…We assumed the existence of the field produced by an electric current flowing through a strip under some sort of symmetrybreaking conditions, for example difference in Sondheimer Fuchs electron scattering at top and bottom NiFe interfaces 27 . We note that if the current distribution is perfectly symmetric, there are no uncompensated Oersted field present in the system and rectification of a non-zero output signal is impossible 16,27 . On the other hand, if one allows the current distribution to produce an uncompensated field, the SD signal will arise.…”

“…Permalloy microstrips provide an excellent ferromagnetic medium to study a nature of SSRW because of relatively low Gilbert damping parameter (α ≈ 0.007) and high anisotropic magnetoresistance (AMR) ratio (up to 4%) 13,14 . These two important features are required for excitation and detection of magnetization dynamics by means of spin diode effect 15,16 . In this work, we demonstrate a voltage control of SSWR and also FMR in NiFe microstrip deposited on PMN-PT piezoelectric substrate.…”