Muons and magnets

Abstract:

We report multifrequency high-field millimeter-wave magneto-optical measurements on the high-spin molecule, Cr10 (OMe) 20 (O2 CCMe3) 10. We find that at temperatures above 15 K and at magnetic fields above 6 T, the simple ESR spectrum expected for a single molecule magnet is markedly altered. Our data strongly suggest the presence of a higher spin excited state multiplet lying only about 10 K above the ground state. © 2006 The American Physical Society.

Abstract:

We present the results of a muon-spin relaxation study of Ge Ni2 O4. We provide further clarification of the two transitions to the antiferromagnetic state and measure the magnetic field dependence of the heat capacity up to 14 T. Both oscillatory and relaxing signals are observed below the lower transition (at temperature TN2) in the muon-decay positron asymmetry spectra, arising from two distinct types of magnetic environment. A possible explanation is suggested in terms of the separate ordering of two magnetic subsystems, one of which does not order fully down to the lowest measured temperature (1.8 K). © 2006 The American Physical Society.