Realization of long-range magnetic order in surface-supported two-dimensional systems has been challenging, mainly due to the competition between fundamental magnetic interactions as the short-range Kondo effect and spin-stabilizing magnetic exchange interactions. Spin-bearing molecules on conducting substrates represent a rich platform to investigate the interplay of these fundamental magnetic interactions. Here we demonstrate the direct observation of long-range ferrimagnetic order emerging in a two-dimensional supramolecular Kondo lattice. The lattice consists of paramagnetic hexadeca-fluorinated iron phthalocyanine (FeFPc) and manganese phthalocyanine (MnPc) molecules co-assembled into a checkerboard pattern on single-crystalline Au(111) substrates. Remarkably, the remanent magnetic moments are oriented in the out-of-plane direction with significant contribution from orbital moments. First-principles calculations reveal that the FeFPc-MnPc antiferromagnetic nearest-neighbour coupling is mediated by the Ruderman–Kittel–Kasuya–Yosida exchange interaction via the Au substrate electronic states. Our findings suggest the use of molecular frameworks to engineer novel low-dimensional magnetically ordered materials and their application in molecular quantum devices.

Several Scanning Probe Microscopy (SPM) methods allow to image dopant profiles in a range from 10 14 cm-3 to 10 19 cm-3 on semiconducting samples. In our work we present Scanning Capacitance Force Microscopy (SCFM) and Kelvin Probe Force Microscopy (KPFM) experiments performed on cross sections of silicon (Si) and silicon carbide (SiC) power devices and epitaxially grown calibration layers. The KPFM signals show under illumination a reduced influence on surface defect states. In addition results from numerical simulation of these microscope methods are discussed.

In recent years the excitonic absorption of CdS at high excitation levels has been studied intensively /l/. Significant non-linear variations of the absorption-and refractive index were found in the spectral range of the AnZl exciton. In spite of differences existing in the explanation of the microscopic origins, it seems to be interesting to take advantage of these variations for the realization of non-linear optical phenomena. A prominent example is the optical bistability demonstrated recently for the exciton absorption of GaAs /2/. In the present note we report on preliminary experimental results on this line for CdS.Vapour-phase-grown CdS platelets (thicknesses some pm) were investigated by three different experimental methods:(i) Probe beam transmission with additional pumping. Two pulsed dye lasers (pulse duration about 4 ns) were used as sources for a broad-band probing beam of low intensity and a high-power pumping beam with frequency at the Bn,l exciton, respectively. Spectra were detected by an OMA system with a spectral resolution of 0.2 meV,(ii) Transmission of a single tunable narrow-band (spectral halfwidth 5 0.2 meV) dye laser beam yielding excitation intensities up to 1 MW/cm at a spot diameter of 0 . 3 mm. The transmitted pulses were detected by a multi-2 plier and measured time-integrated by a boxcar integrator.(iii) Time-resolved detection of the transmission described in (ii) by a fast photodiode and boxcar integrator (time resolution 600 ps).The crystals were cooled only to 77 K. Thus peculiaritiesof the exciton absorption (spatial dispersion, polariton effect, etc. ) appearing at lower temperatures were avoided.Typical spectra of the "pumped" transmission (i) below the A resonance a r e shown in Fig. 1. The overall feature i s an enlargement of the absorption.

Recently, there has been considerable interest to study changes in the refractive index of highly excited direct-gap semiconductors below the band edge. Interference spectroscopy on thin crystal platelets represents an appropriate method for corresponding experimental investigations. First experiments of this kind were reported by Miiller et al. /1/ for CdS. But the purpose of these measurements was mainly a correct determination of the optical gain.Detailed investigations on the refractive index of highly excited CdS were carried out by Klingshirn and co-workers /2/. The thickness of the crystal platelets used was, however, of the order of some microns. From this two difficulties arose:

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This paper reports on the electric field induced absorption change in the situation of zero-dimensional quantum confinement. We have studied CdS rnicrocrystallites embedded in glass by a sensitive modulation spectroscopy technique at room temperature. We observe a two-line spectrum and a quadratic dependence on the applied field. This absorption change is related to the Stark shift of the lowest electron-hole pair state of the quantum dot.Auf der Basis modulationsspektroskopischer Transmissionsmessungen an CdS-Mikrokristallitglasern bei Raumtemperatur wird der EinfluB eines elektrischen Feldes auf die Absorption eines quasinull-dimensionalen Systems untersucht. Das beobachtete Zweilinienspektrum und die dem Quadrat der Feldstarke proportionale Absorptionsanderung werden der Starkverschiebung des Elektron-LochPaar-Grundzustandes zugeordnet.

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A new type of optical bistability is presented. Instead of a resonator the intrinsic feedback between the optical excitation of carriers and their recombination is used. Optical bistability appea,rs, if the absorption coefficient increases with growing carrier density. Both propagation effects and carrier diffusion are considered. Analytical model calculations are carried out for an abrupt behaviour of the absorption coefficient. The results explain the hysteresis in the transmittivity of