Track edges in metal-evaporated tape and thin metal-particle tape

MFM images of tracks written in ME and MP tape have been obtained. The analysis of the images concentrated on the track edges. A track written with signals of 0.5 μm wavelength overwrites a part of a track written with a wavelength of 1 μm. The sharpness of the edges was derived from MFM results. It can be seen that the MP sample shows smaller changes in sharpness of the edge with an increasing write current than ME tape. In ME tape, the region between the λ=0.5 μm and the λ=1 μm parts of the track is much wider than the original λ=1 μm edge

Excitation and spin-transport of hot holes in ballistic hole magnetic microscopy

A hybrid structure of a ferromagnetic Co/Au/Ni81Fe19 trilayer on p-type silicon is used to probe the excitation of electron-hole pairs in a ferromagnet during inelastic decay of hot electrons and the subsequent spin-dependent transport of the excited holes into the valence band of the p-type Si collector. The hole current is remarkably sensitive to magnetic fields, with a magnetocurrent of up to 250% and, unexpectedly, with a positive sign. We determine effective attenuation lengths and their magnetic field and bias voltage dependence.\u

Closed-loop conductance scanning tunneling spectroscopy: demonstrating the equivalence to the open-loop alternative

We demonstrate the validity of using closed-loop z(V) conductance scanning tunneling spectroscopy (STS) measurements for the determination of the effective tunneling barrier by comparing them to more conventional open-loop I(z) measurements. Through the development of a numerical model, the individual contributions to the effective tunneling barrier present in these experiments, such as the work function and the presence of an image charge, are determined quantitatively. This opens up the possibility of determining tunneling barriers of both vacuum and molecular systems in an alternative and more detailed manne

Design fabrication and characterization of an in-plane AFM probe with ultra-sharp silicon nitride tip

Scanning rates of the atomic force microscope (AFM) could be significantly \ud increased by integrating the force sensing probe with microelectromechanical systems (MEMS). We present a micromachining method for batch fabrication of in-plane AFM probes that consist of an ultra-sharp silicon nitride tip on a single \ud crystal silicon cantilever. Our fabrication method is fully compatible with the silicon-on-insulator (SOI) micromachining allowing a straightforward monolithic integration of the AFM probes with high-aspect-ratio monocrystalline silicon MEMS. Scanning probes with a sharp tip having diameter of less then 10 nm are successfully realized and tested in a commercial AFM set-up demonstrating \ud feasibility and the large innovation potential of this method

Batch fabrication of scanning microscopy probes for thermal and magnetic imaging using standard micromachining

We present a process for batch fabrication of a novel scanning microscopy probe for thermal and magnetic imaging using standard micromachining and conventional optical contact lithography. The probe features an AFM-type cantilever with a sharp pyramidal tip composed of four freestanding silicon nitride nanowires coated by conductive material. The nanowires form an electrical cross junction at the apex of the tip, addressable through the electrodes integrated on the cantilever. The cross junction on the tip apex can be utilized to produce heat and detect local temperature changes or to serve as a miniaturized Hall magnetometer enabling, in principle, thermal and magnetic imaging by scanning the probe tip over a surface. We have successfully fabricated a first probe prototype with a nanowire tip composed of 140 nm thick and 11 μ m long silicon nitride wires metallized by 6 nm titan and 30 nm gold layers. We have experimentally characterized electrical and thermal properties of the probe demonstrating its proper functioning. ©2010 IEEE

Ballistic Hole Emission Microscopy on Metal–Semiconductor Interfaces

The transport of hot holes across metal-semiconductor interfaces is studied using ballistic hole emission microscopy. From the tip of a scanning tunneling microscope nonequilibrium holes are injected into a thin metallic overlayer on a p-type Si semiconductor, inducing a current of holes into the Si valence band. We have studied hole transport across interfaces between p-type Si and different metals (Au, Cu, and Al). It is found that the magnitude of the transmitted hole current depends strongly on the type of metal, the Schottky barrier height, and the energy distribution of the holes. In addition, we show that a significant yet smaller hole current can be induced in the reverse case where the tip is used to inject hot electrons, generating holes during inelastic decay in the metal overlayer. The results are compared to recent results on spin-dependent hole transmission in ferromagnet/p-type semiconductor structures

PRAME and CTCFL-reactive TCRs for the treatment of ovarian cancer

Recurrent disease emerges in the majority of patients with ovarian cancer (OVCA). Adoptive T-cell therapies with T-cell receptors (TCRs) targeting tumor-associated antigens (TAAs) are considered promising solutions for less-immunogenic 'cold' ovarian tumors. In order to treat a broader patient population, more TCRs targeting peptides derived from different TAAs binding in various HLA class I molecules are essential. By performing a differential gene expression analysis using mRNA-seq datasets, PRAME, CTCFL and CLDN6 were selected as strictly tumor-specific TAAs, with high expression in ovarian cancer and at least 20-fold lower expression in all healthy tissues of risk. In primary OVCA patient samples and cell lines we confirmed expression and identified naturally expressed TAA-derived peptides in the HLA class I ligandome. Subsequently, high-avidity T-cell clones recognizing these peptides were isolated from the allo-HLA T-cell repertoire of healthy individuals. Three PRAME TCRs and one CTCFL TCR of the most promising T-cell clones were sequenced, and transferred to CD8+ T cells. The PRAME TCR-T cells demonstrated potent and specific antitumor reactivity in vitro and in vivo. The CTCFL TCR-T cells efficiently recognized primary patient-derived OVCA cells, and OVCA cell lines treated with demethylating agent 5-aza-2 '-deoxycytidine (DAC). The identified PRAME and CTCFL TCRs are promising candidates for the treatment of patients with ovarian cancer, and are an essential addition to the currently used HLA-A*02:01 restricted PRAME TCRs. Our selection of differentially expressed genes, naturally expressed TAA peptides and potent TCRs can improve and broaden the use of T-cell therapies for patients with ovarian cancer or other PRAME or CTCFL expressing cancers.Immunobiology of allogeneic stem cell transplantation and immunotherapy of hematological disease

A method to measure the thermovoltage with a high spatial resolution

We have recorded spatial maps of the thermovoltage of a Au(111) surface with a scanning tunneling microscope. The method relies on an approach where we record quasi-simultaneously the normal topography as well as the thermovoltage by switching the feedback and sample bias on and off. This setup can be combined with standard scanning tunneling microscopy and scanning tunnelingspectroscopy techniques. The thermovoltage, which arises from a temperature difference between scanning tunneling microscope tip and sample, is very sensitive to small variations of the local electronic density of states in vicinity of the Fermi level. Near step edges we have observed well-defined Friedel oscillations, while for the herringbone reconstruction, small variations of the local work-function are measured. By altering the tip-sample distance, the thermovoltage contrast can be adjusted