m/sup +/SR studies on pure MnF/sub 2/ and site-diluted (Mn/sub 0. 5/Zn/sub 0. 5/)F/sub 2/

Conference · Wed Jan 01 04:00:00 EST 1986

OSTI ID:5336643

Uemura, Y J; Keitel, R; Senba, M; Kiefl, R F; Kreitzman, S R; Noakes, D R; Brewer, J H; Harshman, D R; Ansaldo, E J; Crowe, K M

Positive muon spin rotation and relaxation measurements have been carried out on the antiferromagnets, pure MnF/sub 2/ and site-diluted (Mn/sub 0.5/Zn/sub 0.5/)F/sub 2/, above and below the Neel temperature T/sub N/ using single-crystal specimens. Two different muon signals have been found in the pure MnF/sub 2/; with the precession frequency nu/sub A/ = 1.3 GHz for the site A and nu/sub B/ = 152 MHz for the site B measured in zero external magnetic field at T = 5 K. We propose a picture that the signal from the A site represents the ''muonium'' state, and discuss the characteristic features of muonium in magnetic materials. The spin relaxation rate 1/T/sub 1/, measured in zero external field, decreases rapidly with decreasing temperature below T/sub N/. The mechanism of the spin relaxation above T/sub N/ is explained by the exchange fluctuations of the Mn moments, while below T/sub N/ by the Raman scattering of spin waves. At the same normalized temperature T/T/sub N/, 1/T/sub 1/ observed in the diluted (Mn/sub 0.5/Zn/sub 0.5/)F/sub 2/ is significantly larger than that in the pure MnF/sub 2/ below T/sub N/. The difference between the pure and diluted systems is related to the large spectral weight of low-energy magnons in (Mn/sub 0.5/Zn/sub 0.5/)F/sub 2/ found by neutron scattering.

• Research Organization: Brookhaven National Lab., Upton, NY (USA); TRIUMF, Vancouver, British Columbia (Canada)
• DOE Contract Number: AC02-76CH00016
• OSTI ID: 5336643
• Report Number(s): BNL-38444; CONF-8606134-6; ON: DE86014853
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360603* -- Materials-- Properties
ASYMMETRY
CHARGED-PARTICLE REACTIONS
FLUORIDES
FLUORINE COMPOUNDS
HALIDES
HALOGEN COMPOUNDS
LEPTON REACTIONS
MANGANESE COMPOUNDS
MANGANESE FLUORIDES
MANGANESE HALIDES
MUON REACTIONS
MUONIUM
NUCLEAR REACTIONS
RELAXATION
SPIN FLIP
SPIN-LATTICE RELAXATION
TEMPERATURE DEPENDENCE
TIME DEPENDENCE
TRANSITION ELEMENT COMPOUNDS
ZINC COMPOUNDS
ZINC FLUORIDES
ZINC HALIDES