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A review of experimental studies of magnon excitations in manganites is presented. A microwave resonance technique, in particular a spin-wave resonance (SWR) technique, is shown to allow the study of not only bulk properties but also surface properties of manganite films. There are two main theoretical approaches used to interpret the SWR spectra: the volume inhomogeneity and the surface inhomogeneity models. The latter, introduced by Puszkarski, allows the interpretation of the observed surface magnon excitations in thin films. It is found that SWR spectra show evidence of manganites, besides bulk spin-wave modes, and also of surface spin-waves. This observation is used to determine the surface magnetic anisotropy. The effect of surface anisotropy on the spin-wave excitation conditions in epitaxial La 0.7 Mn 1.3 O 3-δ films is investigated in detail. SWR data give indirect evidence of periodic charge-ordered stripe formation. A strong effect of thermal annealing on stripe structure is observed and discussed.

Studies of the magnetic properties of LaMn1−xCoxO3 (x = 0.18, 0.36, 0.54) single crystals grown by the electrodeposition method are presented. Magnetization measurements versus temperature and magnetic field are performed in the temperature range from 5 to 300 K and in fields up to 5 T. It is shown that the thermomagnetic irreversibility between MFC(T) and MZFC(T), the values of the magnetic moments of the Co ions, the large positive values of the paramagnetic Curie temperature, the hysteretic character of the M(H) loops, and the large values of the coercive field at low temperatures indicate the dominance of ferromagnetic interactions in these crystals. The results of measurements are analyzed in the framework of the two-phase magnetic state model in the crystal. The blocking temperature, the volume and the number of clusters are estimated for all the crystals studied. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Single crystalline thick films of the superconductor Ba 1-x K x BiO y with wide range of composition x were studied. We first prepared the superconducting films with potassium content x = 0.55 to 0.67. The systematic exploration of the thick films with T c 30-31 K and J c (5 K) 5 x 10 5 Acm -2 (x = 0.36 and 0.38) reveals that for 4.2 to 20 K the field dependences J c (B) are well described by the collective pinning theory. The investigation of the pinning force density Fp(B) shows an unusual scaling behaviour for thick film with x = 0.38.

The law of approach to ferromagnetic saturation for the amorphous Co64Fe14Si11B11 ribbon in the as-quenched state and thinned ribbon and after annealing is investigated. For the sample in the as-quenched state and after polishing of the air side surface the law 1/(μ0H)2 holds in the internal field range 0.030 to 0.100 T. After polishing of the wheel side surface a transition from the 1/(μ0H)2 law to the 1/μ0H law is observed. This behaviour is attributed to different dimensions of defects in the wheel side layer and in the air side layer. Es wird das Einmundungsgesetz zur ferromagnetischen Sattigung in amorphen Co64Fe14Si11B11-Bandern im Ausgangszustand, nach Polierbehandlung und Temperung untersucht. Die Proben im Ausgangszustand und nach Polieren der auseren Oberflache genugen einem 1/(μ0H)2-Gesetz im Feldbereich von 0,030 bis 0,100 T. Nach dem Polieren der inneren Oberflache wird ein Ubergang des Einmundungsgesetzes von 1/(μ0H)2 zu 1/μ0H beobachtet. Dieses Verhalten wird auf die unterschiedlichen Defektabmessungen in der Nahe der auseren und inneren Oberflache zuruckgefuhrt.

The in-plane magnetic anisotropy is measured for FeCrB amorphous alloys rapidly quenched in magnetic field by using FMR technique and BH curve measurements. The magnetic moment and the Curie temperature decrease but the anisotropy has a maximum with increasing Cr content. BH curve measurements show that the magnetic field applied during quenching results in an increase of the bulk in-plane anisotropy. The FMR experimental results suggest that the random surface anisotropy due to surface irregularities is higher than the surface in-plane anisotropy due to the effect of magnetic field in the quenching process. Mittels FMR-Technik und BH-Kurven-Messungen wird die magnetische Anisotropie in der Ebene fur amorphe FeCrB-Legierungen untersucht, die im Magnetfeld schnell abgeschreckt werden. Das magnetische Moment und die Curietemperatur nehmen ab, jedoch zeigt die Anisotropie ein Maximum mit wachsendem Cr-Gehalt. BH-Kurvenmessungen zeigen, das das wahrend des Abschreckens angelegte Magnetfeld zu einem Anwachsen der Volumenanisotropie in der Ebene fuhrt. Die experimentellen FMR-Ergebnisse weisen darauf hin, das die statistische Oberflachenanisotropie infolge von Oberflachenirregularitaten hoher ist als die Oberflachenanisotropie in der Ebene infolge des Einflusses des Magnetfelds wahrend des Abschreckungsprozesses.