K. Rüegg

Muon spin rotation experiments in α-Fe2O3 and Cr2O3

Abstract The behaviour of the stopped muons in the isostructural antiferromagnetic insulators α-Fe 2 O 3 and Cr 2 O 3 indicate a localized state below 500 K. Local fields and relaxation rates are measured and interpreted.

Muon spin rotation in antiferromagnetic oxides

Abstract Muon spin rotation results for antiferromagnetic oxides with the corundum structure are discussed. An attempt to determine the muon stop sites and their chemical environment in these oxides is presented. In addition to the magnetic dipole contribution, a covalent contribution to the effective magnetic field at the muon site is considered. An interpretation of the muon hyperfine interactions in these oxides in terms of muon bond formation, analogous to the hydrogen-oxygen bonding, is given.

Muon spin rotation in orthoferrites ErFeO3 and DyFeO3

AbstractμSR measurements on the rare earth orthoferrites ErFeO3 and DyFeO3 are reported. Experiments have been made as a function of temperature (8–460 K) and the external magnetic field. Above 90 K a single internal field on the order of 2 kG parallel to the c-direction is observed. Zero external field measurements between 50 K and 84 K showed in ErFeO3 two distinct local fields. The external field dependence of the observed frequencies demonstrates that the local field is related to the weak ferromagnetism in both orthoferrites.

Muon states in orthoferrites

L i t t l e is known about the behavior of muons in insu la tors . In contrast to ear ly expectat ions [ l ] muonium formation is seldom observed, but usual ly some kind of a diamagnetic state is formed. Since the muon is essen t ia l l y a magnetic probe, i t may be of advantage to use magnetic insu la tors . In th is paper we repor t on ~SR-experiments on a set of the rare earth o r tho fe r r i t es RFe03 which have well known c r ys ta l lographic [2 ] and magnetic [3] proper t ies. Internal f i e l d measurements were performed on f i ve samples with R = Eu, Dy, Ho, Er, and Y as a funct ion of temperature and appl ied magnetic f i e l d . The resul ts are in terpreted in terms of muon l oca l i za t ion and thermal ly act ivated d i f fus ion .

Local fields at positive muons in magnetic substances

The various contributions to the local field at a positive mouon in ferro- and antiferromagnetic substances are discussed. Formulas for the calculation of the dipolar field tensors are derived. The influence of the oscillation of the muon around its equilibrium site is analyzed.

On the muonium states in silicon

The anomalous muonium state in silicon has been studied with the muon spin rotation technique at low magnetic fields. It was found that the phenomenological description of the anomalous state in terms of an anisotropic Hamiltonian, which is used to explain high field data, is also valid in the low field region. Additional data on muonium states are presented and discussed.