%'e show that low-temperature fluorescence spectra of large high-quality Ctl single crystals are mainly composed of several, independent pairs of T&~false origins. In analogy to the case of anthracene single crystals the series of emission bands can be interpreted in terms of exciton (Frenkel) emission from so-called E traps. Temperature dependent luminescence experiments support this interpretation.

We unravel the origin of current-induced magnetic switching of insulating antiferromagnet/heavy metal systems. We utilize concurrent transport and magneto-optical measurements to image the switching of antiferromagnetic domains in specially engineered devices of NiO/Pt bilayers. Different electrical pulsing and device geometries reveal different final states of the switching with respect to the current direction. We can explain these through simulations of the temperature-induced strain, and we identify the thermomagnetoelastic switching mechanism combined with thermal excitations as the origin, in which the final state is defined by the strain distributions and heat is required to switch the antiferromagnetic domains. We show that such a potentially very versatile noncontact mechanism can explain the previously reported contradicting observations of the switching final state, which were attributed to spin−orbit torque mechanisms.

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Modulated differential scanning calorimetry of sublimed C70 shows clear evidence for four firstorder transitions, two strong and two weak, which we associate with the two different molecular rotational degrees of freedom in majority (equilibrium) and minority (metastable) phases. The latter correspond to two different stacking sequences of close-packed layers, and their relative contributions to the thermal data correlate well with high-temperature x-ray powder-diffraction results. The upper (long axis tumbling) transition in the majority phase exhibits 50 K supercooling when scanned at 2 K/min. Csv impurities at the few '%%uo level depress the transition temperatures substantially. 12 614

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