HIGH-PRESSURE MU-SR STUDIES OF FERRO- AND ANTIFERROMAGNETIC METALS

High-pressure mu SR experiments on ferromagnetic nickel and alpha-iron and antiferromagnetic chromium are reported. In Ni above 260 K B-Ferm i was found to be proportional to the saturation magnetization, wherea s at lower temperatures it is temperature independent apart from a sma ll anomaly below 30 K which is presumably caused by a magnetoelastic i nteraction. There was no evidence for an occupation of metastable site s by the mu(+) below the Curie temperature. By contrast, in alpha-Fe t he temperature dependence of partial derivative B-mu/partial derivativ e p shows a structure which might be attributed to the occupation of e xcited muon states at elevated temperatures. High-pressure zero-field experiments on Cr performed in the temperature regime between 4.5 K an d 8 K revealed a pressure dependence of B-mu as large as partial deriv ative B-mu/partial derivative p = -(89.15+/-0.06) x 10(-12) T/Pa. In t erms of volume dependence a very large negative Gruneisen parameter ga mma = -27 was obtained.