A study on the effect of hydrogen in the compounds with -type structure

The structural and magnetic properties of hydrides with -type structure have been studied by means of magnetic measurements, the neutron powder diffraction technique and self-consistent spin-polarized band calculations (LMTO-ASA). We found that the hydrides retain the -type structure, but with an increase of unit-cell volume. The neutron diffraction results indicate that hydrogen atoms occupy the interstitial 2b sites. Magnetic measurements carried out on , and their hydrides show that both the Curie temperature and the saturation magnetization can be enhanced by introducing interstitial hydrogen atoms. Band-structure calculations and spin-fluctuation theory give a fair description of the enhancement of the magnetization and Curie temperature.