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We present data on the magnetic properties of two classes of layered spin S=1/2 antiferromagnetic quasitriangular lattice materials: Cu 2(1−x) Zn2x(OH)3NO3(0 < x < 0.65) and its long chain organic derivativeswhere non-magnetic Zn substitutes Cu isostructurally. It is found that the long-chain compounds, even in a clean system in the absence of dilution, x = 0, show spinglass behavior, as evidenced by DC and AC susceptibility, and by time dependent magnetization measurements. A striking feature is the observation of a sharp crossover between two successive power law regimes in the DC susceptibility above the freezing temperature. Specific heat data are consistent with a conventional phase transition in the unintercalated compounds, and glassy behavior in the long chain compunds.

Non-uniform optical illuminations near the Schottky interface of Ti/GaAs metal-semiconductor hybrid (MSH) structures induce local photovoltages transverse and lateral to the interface. In these VLSI-compatible, room temperature optical sensors, the optical response of the MSH resistance is directly linked to the Schottky barrier behavior. In order to correlate the interface behavior with the overall heterostructure behavior, quantities such as transverse photovoltage, lateral photovoltage, and resistance are all recorded as a function of laser spot location. The interface's photovoltaic dependence on intensity is consistent with a MSH in which quantum efficiency is independent of optical intensity.

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