An integrated ultra-high vacuum cluster for atomic-scale deposition, interface regulation, and characterization of spintronic multilayers.

The study of interface spin effects in spintronic multilayer films requires distinguishing the effects generated by different interfaces. However, testing in atmospheric conditions requires a capping layer to protect the films, which introduces new interfaces and limits the study of interface spin-dependent effects. To address this challenge, we have developed an integrated ultra-high vacuum cluster system that includes magnetron sputtering equipment, ion irradiation equipment, and time-resolved magneto-optical Kerr effect (TR-MOKE) equipment. Our sputtering system integrates 12 cathodes in a single chamber, allowing the co-sputtering of four targets. The ultimate vacuum can reach 1 × 10-10 mbar, and the deposition resolution of 0.1 nm can be achieved. Ion irradiation equipment can ionize to produce He+, and by screening and accelerating the implantation of He+ into multilayer films, ion scanning is realized, and up to 30 keV energy can be applied to the films. The TR-MOKE equipment can detect ultra-fast magnetic dynamics processes in vacuum conditions, and its external magnetic field can be rotated 360°. Our vacuum cluster system connects the three subsystems, allowing in situ film deposition, regulation, and characterization. By accurately detecting the effects of different layers, the system can distinguish the interface effects of multilayers. Experimental results demonstrate that the three subsystems can work independently or coordinate to observe the interface effects of multilayers.

Electronic and thermal transport properties of the metallic antiferromagnet MnSn2.

We report the structure, magnetic and electrical/thermal transport properties of the antiferromagnet MnSn2. Importantly, the existence of the two antiferromagnetic states below TN2 (∼320 K) is confirmed by magnetism and electrical transport measurements. An unsaturated positive magnetoresistance up to 150% at ∼9 T was observed at 5 K, whereas the magnetoresistance becomes negative in the whole range at high temperatures (T > 74 K). Systematic investigations of the Hall transport and thermoelectric properties reveal that the hole-type carriers are the majority carriers in MnSn2. The kink around 320 K in the Seebeck coefficient originates from the effect of the antiferromagnetic phase on the band structure, while the pronounced peak around 231 K is attributed to the phonon-drag effect. The results suggest that the spin arrangement plays a vital role in the magnetic, electrical, and thermal transport properties in MnSn2.

Fully controllable three-dimensional light-induced longitudinal magnetization using a single objective lens.

With features of fast and energy-efficient data writing, all-optical helicity-dependent switching (AO-HDS) has emerged as a competitive technology to satisfy the demand for the next-generation volume data storage. Unfortunately, to switch the magnetizations in different positions of the magnetic-optic film, the laser beam, the objective lens, or the magnetic recording film should be moved, limiting the advantage of AO-HDS in fast data writing. To achieve on-the-fly magnetization switching, the induced magnetization should be fully controllable. In this Letter, by focusing an azimuthally polarized vortex beam (APVB) and introducing an additional phase, a feasible strategy constructing subwavelength light-induced pure longitudinal multi-magnetization spots is proposed. In addition, the position of the multi-magnetization spots can be dynamically controlled. The distributions of the focused APVBs with different orbital angular momentum, and the induced magnetizations are surveyed. We believe that this is a practical and flexible three-dimensional magnetic recording technique with dynamic control of the recording position.

Tailoring the magnetic field induced by the first higher order mode of an optical fiber.

In this paper, according to the inverse Faraday effect (IFE), the amplitude, phase, polarization and field distribution of the first higher order mode of an optical fiber are tailored carefully, and a magnetic field with arbitrary orientation is generated in the focal region. Compared with traditional strategies to generate a magnetic field with arbitrary orientation, where the configurations are complicated and the components employed for the system are costly, the first higher order mode of a fiber, which has two lobes with opposite instantaneous electric fields, draws more attention for generating a magnetic field with arbitrary orientation. We believe that such an arbitrary orientation state of magnetic field can be applied in the field of confocal and magnetic resonance microscopy and spin dynamics, especially for the use of optical magnetic recording, where laser pulses are used to trigger the magnetization switching.

Flush-mounted probe diagnostics for argon glow discharge plasma.

A comparison is made between plasma parameters measured by a flush-mounted probe (FP) and a cylindrical probe (CP) in argon glow discharge plasma. Parameters compared include the space potential, the plasma density, and the effective electron temperature. It is found that the ion density determined by the FP agrees well with the electron density determined by the CP in the quasi-neutral plasma to better than 10%. Moreover, the space potential and effective electron temperature calculated from electron energy distribution function measured by the FP is consistent with that measured by the CP over the operated discharge current and pressure ranges. These results present the FP can be used as a reliable diagnostic tool in the stable laboratory plasma and also be anticipated to be applied in other complicated plasmas, such as tokamaks, the region of boundary-layer, and so on.