The tertiary pyroelectric effect resulting from the spatially nonuniform distribution of temperature gradient in ferroelectric crystals is studied theoretically and experimentally. A theory of the dynamic pyroelectric effect arising in a free-mounted ferroelectric plate under a temperature gradient is developed. The nonuniform thermal stress and the accompanying polarization are calculated consistently within the framework of the decoupled quasi-static theory of thermoelasticity. The relation between the tertiary pyroelectric effect and variations of the plate shape caused by its nonuniform heating is established and the governing effect of the plate clamping conditions on the evolution of tertiary pyroelectricity is ascertained. The proposed theory has made it possible to suggest and carry out, for the first time, the experiment where the contribution due to tertiary pyroelectricity into the measured integral pyroelectric effect has been figured out. A new physical scheme, where the tertiary pyroelectric effect is utilized, intended for registration of intense laser emission is suggested.

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A strong dependence of tunnel magnetoresistance (TMR) on the crystal orientation of ferromagnetic electrodes was confirmed experimentally. We studied the TMR of Fe/Al2O3/Fe50Co50 tunnel junctions with single-crystal Fe electrodes of different crystal orientations and found that the TMR ratio increased from 13% to 42% at 2K (8% to 26% at room temperature) when the crystal orientation was changed from (100) to (211). Such a TMR anisotropy could be explained in terms of the anisotropic spin polarization of Fe bulk and/or interface electronic states. The importance of the "momentum-filtering" effect of the tunnel barrier was also discussed.c EDP Sciences

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