High‐pressure μSR studies of ferro‐ and antiferromagnetic metals

High‐pressure μSR experiments on ferromagnetic nickel and alpha‐iron and antiferromagnetic chromium are reported. In Ni above 260 K B_Fermi was found to be proportional to the saturation magnetization, whereas at lower temperatures it is temperature independent apart from a small anomaly below 30 K which is presumably caused by a magnetoelastic interaction. There was no evidence for an occupation of metastable sites by the μ⁺ below the Curie temperature. By contrast, in alpha‐Fe the temperature dependence of curpartialB_μ/curpartialp shows a structure which might be attributed to the occupation of excited muon states at elevated temperatures. High‐pressure zero‐field experiments on Cr performed in the temperature regime between 4.5 K and 8 K revealed a pressure dependence of B_μ as large as curpartialB_μ/curpartialp=-(89.15pm 0.06)times 10^-12 T/Pa. In terms of volume dependence a very large negative Grüneisen parameter gamma =-27 was obtained. This revised version was published online in July 2006 with corrections to the Cover Date.