Memristive switching of MgO based magnetic tunnel junctions

Here we demonstrate that both, tunnel magneto resistance (TMR) and resistive switching (RS), can be observed simultaneously in nano-scale magnetic tunnel junctions. The devices show bipolar RS of 6 % and TMR ratios of about 100 %. For each magnetic state, multiple resistive sates are created depending on the bias history which provides a method for multi-bit data storage and logic. The electronic transport measurements are discussed in the framework of a memristive system. Differently prepared MgO barriers are compared to gain insight into the switching mechanism

Detection of a magnetic bead by hybrid nanodevices using scanning gate microscopy

open8sìHybrid ferromagnetic(Py)/non-magnetic metal(Au) junctions with a width of 400 nm are studied by magnetotransport measurements, magnetic scanning gate microscopy (SGM) with a magnetic bead (MB) attached to the probe, and micromagnetic simulations. In the transverse geometry, the devices demonstrate a characteristic magnetoresistive behavior that depends on the direction of the in plane magnetic field, with minimum/maximum variation when the field is applied parallel/perpendicular to the Py wire. The SGM is performed with a NdFeB bead of 1.6 μm diameter attached to the scanning probe. Our results demonstrate that the hybrid junction can be used to detect this type of MB. A rough approximation of the sensing volume of the junction has the shape of elliptical cylinder with the volume of ∼1.51 μm3. Micromagnetic simulations coupled to a magnetotransport model including anisotropic magnetoresistance and planar Hall effects are in good agreement with the experimental findings, enabling the interpretation of the SGM images.openCorte-León, H.; Krzysteczko, P.; Marchi, F.; Motte, J.-F.; Manzin, A.; Schumacher, H. W.; Antonov, V.; Kazakova, O.Corte León, H.; Krzysteczko, P.; Marchi, F.; Motte, J. F.; Manzin, Alessandra; Schumacher, H. W.; Antonov, V.; Kazakova, O

Field-induced p-n transition in yttria-stabilized zirconia

Oxide ion conducting yttria-stabilised zirconia ceramics show the onset of electronic conduction under a small bias voltage. Compositions with a high yttria content undergo a transition from p-type to n-type behavior at voltages in the range 2.4 to 10 V, which also depends on oxygen partial pressure. Surface reactions have a direct influence on bulk electronic conductivities, with possible implications for voltage-induced flash phenomena and resistive switching

Generation of the second harmonic by spin waves propagating in microscopic stripes

Demidov VE, Kostylev MP, Rott K, Krzysteczko P, Reiss G, Demokritov SO. Generation of the second harmonic by spin waves propagating in microscopic stripes. Physical Review B. 2011;83(5): 054408.We have studied experimentally the nonlinear frequency multiplication accompanying propagation of spin waves in microscopic Permalloy stripes. We find that a propagating spin wave efficiently generates another wave at the double frequency. By using an experimental technique with high spatial resolution, we show that the spatial distribution of the amplitude of the nonlinearly generated wave has a symmetry opposite that of the initial wave. We propose a qualitative model explaining this symmetry reversal

Nonlinear Propagation of Spin Waves in Microscopic Magnetic Stripes

Demidov VE, Jersch J, Rott K, Krzysteczko P, Reiss G, Demokritov SO. Nonlinear Propagation of Spin Waves in Microscopic Magnetic Stripes. PHYSICAL REVIEW LETTERS. 2009;102(17): 177207.We have studied experimentally with high spatial and temporal resolution propagation of intense spin waves in microscopic Permalloy stripes. We show that the nonlinearity of the spin system of metallic magnetic films together with microscopic-scale confinement effects lead to an anomalous nonlinear magnetic dynamics, such as a nonlinear spatial self-modulation of spin waves characterized by the repulsive nonlinearity. This phenomenon appears to be densely connected with the nonlinear damping in the system. We find that both of these effects develop synchronously on the nanosecond temporal scale