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Selected results of department 12

Raman spectra of PZT ceramics were studied systematically in a broad temperature interval (10–600 K) and a broad Ti/Zr concentration range around the morphotropic phase boundary (x = 0.25–0.70) [E. Buixaderas et al., Phys. Rev. B 91, 014104 (2015)]. The whole text »

The seminal paper by Zhirnov (1958 Zh. Eksp. Teor. Fiz. 35 1175–80) explained why the structure of domain walls in ferroelectrics and ferromagnets is so different. We have recently realized that the antiparallel ferroelectric walls in rhombohedral ferroelectric BaTiO3 can be switched between the Ising-like state (typical for ferroelectrics) and a Bloch-like state (unusual for ferroelectric walls but typical for magnetic ones) [see Fig. 1] by a compressive epitaxial stress. The whole text »

Ultrafast electron dynamics and short-range electron transport in CdS nanocrystals prepared by chemical-bath deposition were investigated in terahertz regime [Z. Mics et al., Phys. Rev. B 83, 155326 (2011)]. Initially high mobility of photogenerated electrons exhibits a decrease within 1 picosecond due to the relaxation of their excess energy. Role of nanocrystal surfaces and nanocrystalline aggregates in electron transport was elucidated.

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Bismuth ferrite (BiFeO3) is a prototypical multiferroic system exhibiting extraordinary properties; it is ferroelectric up to TC ~ 1100 K as well as antiferromagnetic up to TN ~ 640 K. Characterisation of polar phonon modes is essential for understanding its dielectric and electromechanical behaviour. The whole text »

Unique sequence of phases was discovered in a chiral smectic, namely reentrance of orthogonal paraelectric A phase below the ferroelectric C phase. This behavior was explained by non-monotonous temperature dependence of the principal coefficient in the free energy expansion and microscopically by changes of molecular conformations and intermolecular distances due to occurrence a lateral bulky group in the molecule. This phenomenon is accompanied with anomalies in dielectric, optical and switching properties. The whole text »

Magnetoelectric multiferroics are materials, which exhibit simultaneously magnetic and ferroelectric order. There is theoretically possible to influence magnetic or ferroelectric domains with electric or magnetic fields, respectively, therefore these materials are intensively studied for their promising potential applications in non-volatile memories. Unfortunately, there are only few multiferroics in nature and most of them work only at low temperatures. We suggested to use large mechanical strain in ultrathin films for preparation of new „artificial“ multiferroics. The whole text »

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