M. Trhlík

Nuclear spin-lattice relaxation of60Co in ferromagnetic alloys Pt99Co1 and Pd99Co1

Nuclear spin-lattice relaxation (SLR) of60Co in the systems Pt99Co1, Pd99Co1 has been studied by very low temperature nuclear orientation technique. The thermal cycling method has been used. The difference of two orders of magnitude of Korringa constant has been found between Pt99Co1 and Pd99Co1.

Hyperfine field anisotropy in YIG with diamagnetic impurities

Abstract The 57 Fe NMR spectra of pure yttrium iron garnet, measured at 4.2 K, exhibit a well-resolved satellite structure caused by antisite defects (yttrium ions replacing iron on a sites). The analysis of the a site spectra, obtained in a magnetic field of 0.75 T applied in several directions in the (1 1 0) plane, yielded the values of the isotropic and anisotropic terms of the hyperfine field for four resolved satellite sets.

Unusual magnetic behaviour of Mn spin in magnetic PtFe alloys: Nuclear orientation study

The low temperature nuclear orientation of54Mn in Pt99Fe1, Pt99,9Fe0.1 and Pt99,95Fe0.05 has been studied in the temperature rangé 5–60 mK and in the external magnetic field range 0–9 T. A considerable noncollinearity of Mn magnetic moments with respect to Bext has been found even at rather high Bext.

Nuclear orientation study of160Tb impurity in gadolinium single crystal

The low temperature nuclear orientation of160Tb in gadolinium single crystal has been studied in the temperature range 5–60 mK and in the external magnetic field Bext ≤9 T, applied both in the a- and c-axis directions. The obtained results indicate the noncollinearity between the Tb magnetic moments and the magnetization of the gadolinium matrix.

Nuclear orientation study of160Tb impurity in yttrium single crystal

The low temperature nuclear orientation of160Tb impurity in yttrium single crystal has been studied in the temperature range 5–60 mK and in the external magnetic field up to 9 T applied along a- or c-crystal axes. The experimental results are interpreted as a consequence of the interaction of Tb3+ ion with crystal field produced by the yttrium neighbours. A possible influence of technology used is also discussed.

Observation of Mn spin canting in PtFe alloys at low temperatures

The low-temperature nuclear orientation of 54Mn in Pt99Fe1 and Pt99.95Fe0.05 has been studied in the temperature range 12-50 mK and in the external magnetic field range 0-1.2 T. The strong temperature and external magnetic field dependence of the effective field Beff on 54Mn has been observed even in the range where the host itself is magnetically saturated. This behaviour is interpreted by noncollinearity of the Mn magnetic moments with respect to the macroscopic magnetisation direction.

160Tb nuclear orientation in yttrium single crystal

First experimental results of160Tb nuclear orientation in yttrium single crystal matrix are described. The influence of external magnetic field in combination with the crystal field interaction is discussed.

The new nuclear orientation facility at charles university prague

The Nuclear Orientation facility for solid state physics investigations was installed at the Department of Low Temperature Physics of the Faculty of Mathematics and Physics, Charles University. The small “top loaded” dilution refrigerator is used for cooling radioactive metallic samples to 10 mK in 4 T magnetic field. The construction and thermodynamic parameters of the “French type” refrigerator working without 1 K precooling stage are described.

Nuclear spin-lattice relaxation in ferromagnetic amorphous alloys Fe81Co3B16 andFe70Co10B20 measured by NMR and Nuclear orientation

The nuclear spin-lattice relaxation of59Co in amorphous Fe-Co-B alloys was studied by NMR andthe results were compared with nuclear orientation measurements. The NMR relaxation rates were evaluated taking into account the electric quadrupole interaction. Then the results of both methods are in good agreement. It was confirmed that the spin-lattice relaxation is independent of the external magnetic field in the magnetically saturated samples andit was found that it does not depend on Co concentration.

Nuclear spin-lattice relaxation of 60Co in the glassy alloy Co3.1Fe80.5B16.4 studied by low-temperature nuclear orientation

The hyperfine field and nuclear spin-lattice relaxation of 60Co in the glassy alloy Co3.1Fe80.5B16.4 have been studied by low-temperature nuclear orientation technique. The thermal cycling method has been used for relaxation measurement. In comparison with the crystalline Fe matrix, the nuclear spin-lattice relaxation of 60Co in the glassy alloy has been found to be five times faster and shows no dependence on external magnetic field in the range 0.1-1.1 T. Wegers mechanism is proposed to play a crucial role in the nuclear spin-lattice relaxation in this material.