RKKY-like contributions to the magnetic anisotropy energy: 3d adatoms on Pt(111) surface

The magnetic anisotropy energy defines the energy barrier that stabilizes a magnetic moment. Utilizing density functional theory based simulations and analytical formulations, we establish that this barrier is strongly modified by long-range contributions very similar to Frieden oscillations and Rudermann-Kittel-Kasuya-Yosida interactions. Thus, oscillations are expected and observed, with different decaying factors and highly anisotropic in realistic materials, which can switch non-trivially the sign of the magnetic anisotropy energy. This behavior is general and for illustration we address transition metals adatoms, Cr, Mn, Fe and Co deposited on Pt(111) surface. We explain in particular the mechanisms leading to the strong site-dependence of the magnetic anisotropy energy observed for Fe adatoms on Pt(111) surface as revealed previously via first-principles based simulations and inelastic scanning tunneling spectroscopy (A. A. Khajetoorians et al. Phys. Rev. Lett. 111, 157204 (2013)). The same mechanisms are probably active for the site-dependence of the magnetic anisotropy energy obtained for Fe adatoms on Pd or Rh(111) surfaces and for Co adatoms on Rh(111) surface (P. Blonski et al. Phys. Rev. B 81, 104426 (2010)).Comment: published manuscript with additional figures and comment

Printed circuit board based segmented quadrupole ion guide

Collisional damping quadrupole ion guides have become popular tools in mass spectrometry. In such devices, ions are cooled by collisions with a buffer gas and focused to trajectories near the axis of the ion guide under the influence of a radio frequency (RF) field. This produces a narrow beam of low-energy ions which can be transported with high efficiency. Typically, quadrupole ion guides are constructed of four parallel rods to which RF voltages are applied. To overcome the dampening of the axial velocity component resulting from collisions with neutral gas particles, an additional static axial field is provided by dividing the rods in several segments and applying an electric potential to each segment. However, this method is mechanically complex, requiring a precise alignment of all segments, and several separate connections for the DC und RF voltages to all segments. In this work, we present a simple and low-cost segmented quadrupole ion guide design that is based on standard printed circuit boards (PCB) including both the segmented electrodes as well as the signal distribution network. Furthermore, we present simulations of the ion movement inside this PCB quadrupole and experimentally evaluate the ion transfer. Our measurements show that the segmented PCB quadrupole with planar electrodes reaches similar ion transmissions in comparison with conventional quadrupole ion guides built from segmented circular rods

Curse or Blessing? Exploring risk factors of digital technologies in industrial operations

Both practitioners and scholars emphasise the benefits of Industry 4.0 (I4.0) technology implementation, such as increased transparency and the availability of real-time data in operations processes. Current literature on I4.0 technologies tends to overemphasise the positive impact and transformational capabilities of digital technologies while there is little focus on evaluating potential risks associated with their adoption in industrial operations. An understanding of how supply chain risks are perceived in digitalisation projects within industrial operations and an understanding of decision-makers' responses to different types of risks has important managerial implications. Current literature, however, lacks systematic empirical evidence on the implementation of I4.0 applications and related risk factors. This study aims to address this research gap by exploring the relationship between I4.0 technologies and supply chain risks based on empirical evidence from 300 case studies of industrial practice in Germany and fifty-three interviews with relevant managers from selected use cases and with general experts in this field. Our findings show that digital technologies are frequently adopted to address certain existing supply chain risks but that their implementation introduces new sources of risks (e.g. cyber risks). Based on qualitative data analysis and drawing on Normal Accident Theory, we propose a framework to explicate the drivers and contingency factors of new sources of supply chain risks in the context of Industry 4.0 technologies. Practical recommendations are provided for supply chain managers to guide the process of managing supply chain risks based on the technological life cycle