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Electric control of exchange bias (EB) is of vital importance in energy-efficient spintronics. Although many attempts have been made during the past decade, each has its own limitations for operation and thus falls short of full direct and reversible electrical control of EB at room temperature. Here, a novel approach is proposed by virtue of unipolar resistive switching to accomplish this task in a Si/SiO2 /Pt/Co/NiO/Pt device. By applying certain voltages, the device displays obvious EB in the high-resistance-state while negligible EB in the low-resistance state. Conductive filaments forming in the NiO layer and rupturing near the Co-NiO interface are considered to play dominant roles in determining the combined resistive switching and EB phenomena. This work paves a new way for designing multifunctional and nonvolatile magnetoelectric random access memory devices.

An obvious asymmetry of ascending and descending branches of the hysteresis loop appeared in the NiFe/FeMn bilayers with thin FeMn layers designed for studying a domain wall structure (DWS) existing at the F/AF interface. For theoretical fitting of the asymmetrical hysteresis loops, we proposed a model of hybrid interfacial DWS in F/AF bilayers, in which the existence of partial domain walls in both layer sides is considered. Numerical results based on the model of hybrid interfacial DWS are presented and agree with experimental results well. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Ferromagnetic resonance(FMR) study on sputtered Ni80Fe20 with various thickness from 2 nm to 38.5 nm sandwiched by Ta has been made systematically with different dc magnetic field orientations. The FMR spectra were analyzed and fitted theoretically with Laudau-Lifshitz-Gilbert equation. The variations of magnetization, magnetic anisotropy up to fourth-order term with thickness of samples were obtained. The analysis of the FMR peak-to-peak linewidth was made by the homogenous and inhomogeous contributions, and the damping constants of samples were calculated. The experimental data were fitted by theoretical model and there were some abnormal changes in the magnetic parameters with the sample thickness. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Permalloy (Py)/capping (FeMn, Ta) bilayers with interconnected network structure were deposited onto porous alumina templates with 5.0 nm thick Ta buffer layers. For the nanostructured Py/FeMn and Py/Ta bilayers the coercivity goes through a maximum value near the Py layer thickness of 17.5 nm. Despite exchange biasing, however, the coercivity of the former bilayers is smaller than that of the latter ones with the same Py layer thickness. The Ta capping layer thickness and the deposition rate of the Py layer are also found to have great influences on the coercivity of the Py layer. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The plateaus in laser-assisted recombination and high-order harmonic generation are investigated in the frequency domain. It is found that the probability amplitude of finding an electron with a given energy is given by a generalized Bessel function, which can be represented as a coherent superposition of contributions from a few electronic quantum trajectories. This concept is illustrated by comparing the spectral density of the electron with the laser-assisted recombination spectrum. On the other hand, the plateau of high-order harmonic generation reflects the spectral density of the electron at the location of the nucleus after above-threshold ionization.

The magnetic properties of sputtered Co/Pb multilayers have been studied by vibrating-sample magnetometer (VSM), torque magnetometer and ferromagnetic resonance spectroscopy (FMR). Magnetic measurements show that with decreasing Pb layer thickness the perpendicular anisotropy field H u increases from 5.7 to 8.3 kOe. The interfacial anisotropy is obtained to be as small as K s = 0.006 erg/cm 2 . It is demonstrated that the increase of H u with decreasing Pb layer thickness is due to the variation of texture in h.c.p. Co along the [00.2] direction with spacer thickness. The in-plane magnetic hysteresis loops show a higher saturation field and smaller remanence ratio for thin spacer films which cannot be accounted for solely by H u and indicates the existence of antiferromagnetic (AFM) coupling between Co layers through Pb spacer. The interlayer coupling is also implied by the observation of spin wave resonance (SWR) in perpendicular FMR. From the SWR spectrum the effective exchange constant is obtained as A eff = 3.4 x 10 -7 erg/cm. A resonance peak appears on the high-field side of the uniform FMR mode, which is attributed to the AFM coupling of adjacent ferromagnetic layers producing an optical mode. The Pb layer thickness (t Pb ) dependence of the separation of the resonance fields, ΔH, between the optical mode anti uniform mode in the perpendicular FMR spectrum is fitted by ΔH = 2.80 exp (-(t Pb - 1))/1.78 (kOe) with a characteristic thickness of 1.78 nm. Thus, the coupling strength (J = M s t Co ΔH/2), in proportion to ΔH, decreases exponentially with Pb layer thickness, which is consistent qualitatively with the variation of the in-plane remanence ratio with spacer thickness.