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The spin-mixing conductance (SMC) is an essential parameter for ferromagnetic-insulators-based spintronics devices. Here, we study the influence of device boundary on local spin transport properties in platinum (Pt)/yttrium iron garnet (YIG) films by reducing the lateral size of the devices. An obvious fluctuation of spin Hall magnetoresistance, Gilbert damping coefficient, and effective spin Hall angle with restricting the size of YIG films has been found at room temperature. By employing both harmonic and current-induced spin-torque ferromagnetic resonance measurements, we have found a negligible fluctuation of both the imaginary part of SMC and effective magnetization with varying the geometric size of devices. In contrast, the real part of SMC at the Pt/YIG interface has been rigidly altered. Our results show that the SMC dramatically depends on the boundary effect from Ar+-ion milling. [ABSTRACT FROM AUTHOR]

SnO2 quantum dots (QDs) are potential materials for deep ultraviolet (DUV) light emitting devices. In this study, we report the temperature and excitation power-dependent exciton luminescence from SnO2 QDs. The exciton emission exhibits anomalous blue shift, accompanied with band width reduction with increasing temperature and excitation power above 300K. The anomalous temperature dependences of the peak energy and band width are well interpreted by the strongly localized carrier thermal hopping process and Gaussian shape of band tails states, respectively. The localized wells and band tails at conduction minimum are considered to be induced by the surface oxygen defects and local potential fluctuation in SnO2 QDs. [ABSTRACT FROM AUTHOR]

We report spin–orbit torques (SOT) in a L10-ordered perpendicularly magnetized FePt single layer, which is significantly influenced by disorder. Recently, self-induced SOT in the L10-FePt single layer has been investigated, which is ascribed to the composition gradient along the normal direction of the film. However, the determined mechanisms for magnetization switching have not been fully studied. With varying growth temperatures, we have prepared FePt single layers with the same thickness (3 nm) but with different disordering. We have found that nearly full magnetization switching only happens in more disordered films, and the magnetization switching ratio becomes smaller with increasing L10 ordering. The method for deriving effective spin torque fields in the previous studies cannot fully explain the spin current generation and self-induced SOT in the L10-FePt single layer. Combined with the magneto-optical Kerr effect microscopy and anomalous Hall effect measurements, we concluded that the disorder should determine the formation of domain walls, as well as the spin current generation. [ABSTRACT FROM AUTHOR]

The combined effect of the spin-transfer torque and circular Amperian field to the switching of the chiralities of the dual-vortex magnetization in multilayered Ni80Fe20/Cu/Co nanopillar elements (o\ = 100 nm) is investigated numerically. It is demonstrated that, by passing a current pulse through the nanopillar, the chirality of the Ni80Fe20 layer can be controllably switched while that of the fixed Co layer persists. Consequently, reliable toggle switching between bistable low- and high-MR states can be achieved by applying current pulses with appropriate amplitude, polarity, and duration. It is found that the magnetization dynamics after the onset of a current pulse includes the excitation of spin-wave eigenmodes and that the predominant process throughout is the precessional motion of the free-layer magnetization. A shift of the eigenfrequency is observed when the chirality of the free-layer vortex magnetization switches from parallel to antiparallel relative to that of the fixed layer. This frequency shift is attributed to dynamic magnetostatic coupling between the vortices. [ABSTRACT FROM AUTHOR]

We have compared the spin orbit torque (SOT) induced magnetization switching in Pt/Co/Pt/ Y3Fe5O12 (YIG) and Pt/Co/Pt/SiO2 multilayers. The critical switching current in Pt/Co/Pt/YIG is almost half of that in Pt/Co/Pt/SiO2. Through harmonic measurements, we demonstrated the enhancement of the effective spin Hall angle in Pt/Co/Pt/YIG. The increased efficiency of SOT is ascribed to the nonequilibrium proximity effect at the Pt/YIG interface, which suppresses the spin current reflection and enhances the effective spin accumulation at the Co/Pt interface. Our method can effectively reduce the switching current density and provide another way to modulate SOT. [ABSTRACT FROM AUTHOR]

The room-temperature weak ferromagnetism of amorphous HfAlOx thin films deposited by pulsed laser deposition on various substrates in oxygen-defective ambient is demonstrated. The magnetization is independent of film thickness, but depends on substrates and deposition temperatures. A magnetic moment of ∼0.26μB per HfAlOx f.u. is recorded for HfAlOx films deposited under optimized conditions [deposited at 600 °C on (001) sapphire in high vacuum]. It is argued that interfacial defects are one of the possible sources of the weak ferromagnetism. [ABSTRACT FROM AUTHOR]

The crystal structure and magnetic properties of SmCo7-xSix (x=0.1–0.9) compounds were studied by means of x-ray powder diffraction and magnetic measurements. Rietveld refinement of x-ray powder diffraction pattern shows that the as-cast compound SmCo7-xSix with x=0.9 crystallizes in the TbCu7-type structure with the space group P6/mmm, and the doping element Si has a distinct preference to occupy the 3g site. According to the refinement result, the composition of the compound is derived as SmCo5.85Si0.90. The compound SmCo5.85Si0.90 exhibits ferromagnetic order with the Curie temperature of about 717 K and a saturation moment of about 6.58±0.05 μB/f.u. The SmCo5.85Si0.90 compound shows a strong uniaxial magnetocrystalline anisotropy, and an anomalous increase of magnetization at low temperature is observed in an external field applied perpendicular to the easy direction of magnetization. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Recently, the magnetocaloric effect (MCE) of Ni-Mn-based Heusler alloys has attracted more attention due to its metamagnetic shape-memory effect. However, most MCE investigations focused on the bulk alloys developed at high magnetic field (>2 T). In this paper, by employing the melt-spinning technique, a large MCE at low magnetic field was found in a ribbon of Ni50-xCoxMn35In15. The magnetic entropy change ΔS reaches the maximum value of 5.35 J/kg K at 1 T field in the Ni49CoMn35In15 ribbon near room temperature, and its corresponding temperature span arrives 24 K. The refrigerant capacity is enhanced with the increase of the Co substitution. Such a large MCE at low magnetic field in the Ni50-x CoxMn35In15 ribbon with a wide temperature range provides a potential candidate for room temperature magnetic refrigeration. [ABSTRACT FROM AUTHOR]