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Selected results of department 11

The rare earth (4f) intermetallic compounds with Fe or Co are famous as extremely powerful permanent magnets with exceptionally high uniaxial magneto-crystalline anisotropy. In R2Co17 compounds (R is a rare-earth metal), the strongest interaction is the Co-Co exchange interaction which primarily determines their Curie temperature, TC. The whole text »

The exchange interaction through interface of dissimilarly ordered magnetic materials (e.g. an antiferromagnet (AF) in contact with a ferro- or ferrimagnet (F)) gives rise to a characteristic exchange bias (EB) effect [1] (i.e. shifted magnetic hysteresis loop with an enhanced coercivity), which is of fundamental importance for novel hard magnets, recording media, spin valve and tunneling devices. The whole text »

The electrical activity of superfluid 4He induced by the relative motion of normal and superfluid components has been recently observed. It was induced in two different types of experiments. In a first experiment the electric potential oscillations were generated by a wave of second-sound, the out-of-phase oscillation of the normal and superfluid components. In a second experiment liquid helium was involved in motion by a torsional oscillator whose walls affected the normal component only. The whole text »

We are studying experimentally the turbulent state of bellows-driven 4He superfluid flows in channels. Turbulence in a superfluid takes the form of a tangle of atomically-thin vortex lines with quantized velocity circulation, which arise as a consequence of the Bose-Einstein condensation of the superfluid [1]. In one project [2-4] we have studied the dependence of the total length of vortex lines, L, with mean flow velocity, v, in conditions of steady-state turbulence. The whole text »