E. Kisker

Leadless pacing of the heart using induction technology: a feasibility study.

Objectives: To develop a leadless pacemaker system based on induction technology and to investigate its feasibility and safety in the pig model.

Antiferromagnetic Coupling of a Cr Overlayer to Fe(100)

The magnetic moment of Cr overlayers deposited on Fe(100) was investigated by spin-resolved core level photoemission. Data for the Cr 3p level show that a monolayer of Cr is ferromagnetically ordered with a magnetic moment oriented antiparallel to the Fe moments. The results suggest that at room temperature the moment of a Cr monolayer on Fe is of the order of 0.5 to 1μB per Cr atom.

Magnetic linear dichroism in soft X-ray core level photoemission from iron

Abstract We have observed magnetic linear dichroism in soft x-ray core-level photo-emission from ferromagnets: With linearly polarized light, the Fe 3p lineshape depends strongly on the relative orientation of the light electric field vector E and the magnetization vector M . For s-polarized light and collinear orientation of E and M the core level line shows a single peak. With E ⊥ M a double-peaked line is observed. We attribute this change to the MLD effect as predicted recently 1 .

Magnetic properties of Cr overlayers on Fe (invited)

The magnetic properties of Cr overlayers deposited on Fe(100) were investigated by spin‐resolved photoemission. Valence band spectra show a reduction of the overall polarization after deposition of Cr. Data of the Cr 3p core level show for Cr coverages up to about 2 monolayers a polarization opposite to that of the Fe 3p core level. Both findings are evidence for an orientation of the Cr moments antiparallel to the Fe moments. The core level as well as the valence band results are consistent with an average moment of about 1 μB per Cr atom, which is significantly smaller than calculated for a monolayer of Cr on Fe.

High-efficiency spin polarimetry by very-low-energy electron scattering from Fe(100) for spin-resolved photoemission

We describe concept, design, and performance of a novel spin polarimeter based on spin-dependent specular reflection of electrons from a Fe(100) surface. The Fe surface is prepared as an ultrathin film on Ag(100). By tuning the energy of the electrons to a critical point in the Fe band structure, a large spin asymmetry combined with a large scattering efficiency is achieved. The polarimeter yields a figure of merit up to 10−2 for the best Fe(100) surfaces.We describe concept, design, and performance of a novel spin polarimeter based on spin-dependent specular reflection of electrons from a Fe(100) surface. The Fe surface is prepared as an ultrathin film on Ag(100). By tuning the energy of the electrons to a critical point in the Fe band structure, a large spin asymmetry combined with a large scattering efficiency is achieved. The polarimeter yields a figure of merit up to 10−2 for the best Fe(100) surfaces.

Spin-polarized electron spectroscopy as a combined chemical and magnetic probe

Abstract Photoelectron spectra of inner core states of magnetic material show polarization features determined by the magnetic properties of the valence electrons. This offers a new possibilty of using electron spectroscopy as a magnetic probe. The low intensity of these photoemission lines led us to use very-low-energy-electron-scattering from Fe as spinpolarimeter with an efficiency about 20 times higher than previously used spin detection techniques. First experiments on the Fe 3p and 3s core levels confirm exchange split lines. For thin Cr overlayers on Fe(001) we find the polarization of the Cr 3p level for Cr coverages up to two monolayers to be opposite to that of the Fe 3p core level. Effects of the film thickness on the spin-resolved core level spectra are discussed.

Observation of in plane magnetization reversal using polarization dependent magneto-optic Kerr effect

We present an experimental setup for in plane two axis magnetometry using the polarization dependent magneto–optic Kerr effect (MOKE). A conventional setup to measure longitudinal MOKE with crossed polarizers is extended by a Faraday cell to compensate for the rotation of the polarization vector caused by a magnetized sample. The shape of the hysteresis loops measured on thin FeNi alloy films depends strongly on the angle between the optical axis of the analyzer and the plane of incidence. We derive expressions for the compensation angle which allow for extraction of vectorial magnetic information from loops detected with oblique polarization. For a small deviation from pure s or p polarization the transverse magnetization is found to be proportional to the difference between the loop obtained with oblique polarization and the one obtained with pure s or p polarization. Thus the complete in plane reversal process split up into longitudinal and transverse components can be observed.

Linear magnetic dichroism in photoemission

Results for the linear magnetic dichroism of Fe 2p spin-resolved photoemission with high energy resolution are reported. The results are qualitatively similar to those for the 3p level, with the advantage that the fine structure split sublevels (j = 1/2 and j = 3/2) are well separated, facilitating comparison with theoretical models. The finite dichroism in the energy region between the two photoemission peaks is not caused by secondaries, but appears to be a nontrivial effect. The 3p dichroism depends on photon energy: it is maximum at 140 eV, and vanishes around 300 eV photon energy.

Magnetic linear dichroism in angle-resolved valence band photoemission from Fe(001)

Abstract We report the observation of magnetic linear dichroism in angle resolved valence band photoemission from Fe(001), manifesting itself in a change of the spectrum upon reversal of the magnetization direction.

Leadless pacing using induction technology: impact of pulse shape and geometric factors on pacing efficiency

AIMS Leadless pacing can be done by transmitting energy by an alternating magnetic field from a subcutaneous transmitter unit (TU) to an endocardial receiver unit (RU). Safety and energy consumption are key issues that determine the clinical feasibility of this new technique. The aims of the study were (i) to evaluate the stimulation characteristics of the non-rectangular pacing pulses induced by the alternating magnetic field, (ii) to determine the extent and impact of RU movement caused by the beating heart, and (iii) to evaluate the influence of the relative position between TU and RU on pacing efficiency and energy consumption. METHODS AND RESULTS In the first step pacing efficiency and energy consumption for predefined positions were determined by bench testing. Subsequently, in a goat at five different ventricular sites (three in the right ventricle, two in the left ventricle) pacing thresholds using non-rectangular induction pulses were compared with conventional pulses. Relative position, defined by parallel distance, radial distance, and angulation between TU and RU, were determined in vivo by X-ray and an inclination angle measurement system. Bench testing showed that by magnetic induction for every alignment between TU and RU appropriate pulses can be produced up to a distance of 100 mm. In the animal experiment pacing thresholds were similar for non-rectangular pulses as compared with conventional pulse shapes. In all five positions with distances between 62 and 102 mm effective pacing was obtained in vivo. Variations in distance, displacement and angle caused by the beating heart did not cause loss of capture. At pacing threshold energy consumptions between 0.28 and 5.36 mJ were measured. Major determinants of energy consumption were distance and pacing threshold. CONCLUSION For any given RU position up to a distance of 100 mm reliable pacing using induction can be obtained. In anatomically crucial distances, up to 60 mm energy consumption is within a reasonable range.