The nuclear forward scattering (NFS) of synchrotron radiation is especially
suited for probing magnetism at high pressure (h.p.), here in the Mbar ran
ge, by the nuclear resonances of Fe-57 and Eu-151. We report on high-pressu
re NFS studies with the 14.4 keV transition of Fe-57, presenting at first t
he pressure induced alpha-epsilon transformation in iron. Then a systematic
study of magnetic RFe2 Laves phases of cubic C15 structure (YFe2, GdFe2) a
nd hexagonal C14 structure (ScFe2, TiFe2) at pressures up to 100 GPa (= 1 M
bar) is given. First, high-pressure NFS studies performed with the 21.5 keV
resonance of Eu-151 are also presented, probing valence transitions in EuN
i2Ge2 and the magnetism in the CsCl-type h.p. phase of EuTe. Finally, we di
scuss future applications, such as high-pressure studies of phonon densitie
s of states, using the inelastic channel of nuclear scattering of synchrotr
on radiation.