Observation of an oscillatory behavior of the zero-field μ+ spin relaxation function in pure copper

High precision measurements were carried out on the zero field (ZF) spin relaxation function of μ⁺ in copper at 14.8 K, where μ⁺ is nearly localized. The time spectrum obtained shows an oscillatory deviation from the dynamical Kubo-Toyabe relaxation function. The deviation seems to come mainly from the distribution of local field different from a gaussian distribution.     

Spin fluctuation of itinerant electrons in MnSi probed by μ+

Conclusion To our knowlge, this is the first experimental work to show the divergent behavior of 1/T₁ at T_C in weak itinerant ferromagnetic systems, and we conclude that there is general agreement between the present results and the SCR theory.Work supported by Japan Society for the Promotion of Science, the Toray Science Foundation, the Grant-in-Aid of the Japanese Ministry of Education, Culture and Science, and the Atomic Energy Control Board and National Research Council of Canada.     

Hemoglobin magnetism in aqueous solution probed by muon spin relaxation and future applications to brain research

A marked difference in spin relaxation behavior due to hemoglobin magnetism was found for positive muons (μ⁺) in deoxyhemoglobin in comparison with that observed in oxyhemoglobin in aqueous solution at room temperature under zero and external longitudinal magnetic fields upto 0.4 Tesla. At the same time, small but significant unique relaxation pattern was observed in nonmagnetic oxyhemoglobin. Combined with our previous measurements on hemoglobin in human blood, application of this type of measurement to the studies of the level of oxygenation in various regions of the human brain is suggested.     

A μSR study on chemical behaviors of positive muons in crystalline tris/acetylacetonato/metal/III/ complexes

Chemical behaviours of positive muons implanted in crystalline tris/acetylacetonato/chromium/III/, iron/III/, and cobalt/III/ were investigated by means of the muon spin relaxation technique. The muon spin relaxation function was exponential in tris/acetylacetonato/iron/III/ and Gaussian in tris/acetylacetonato/cobalt/III/, suggesting that the muon spin relaxation may be ascribed to the interaction between the muon spin and a fluctuating electronic spin in the former and between the muon and a static nuclear spin in the latter. The yield of diamagnetic muon species was found to be nearly unity in these three complexes. Based on the analysis of the relaxation function, it is likely that the positive muon implanted in the cobalt/III/ complex will reside at a distance of about 1.7 A from the cobalt atom.     

Theory of location and associated hyperfine properties of the positive muon in La2CuO4

The current understanding regarding the location of the positive muon, which is a valuable tool for probing the magnetic properties of copper oxide superconducting systems, will be reviewed for La₂CuO₄. The results of our present investigations by the Unrestricted Hartree-Fock Cluster procedure, which leads to a location for the muon of about 1.08 Å away from an apical oxygen and with the O-⁺ direction making an angle of 25° with the O-Cu direction, will be discussed, including the magnitude and direction of the hyperfine field obtained from the calculated wave functions. These latter results, which are in reasonable agreement with earlier muon spin rotation data in powdered samples and recent data in single crystals, show the importance of including the local contact and dipolar contributions to the hyperfine field associated with the unpaired electron spin distribution in the neighborhood of the muon. Possible additional factors besides those included here, that will involve substantial computational efforts but could lead to a bridging of the remaining quantitative differences with experimental hyperfine data, will be discussed.     

X-ray measurement on muon to alpha sticking in muon catalyzed d-t fusion; present and future

Among a series of X-ray experiments on the muon catalyzed fusion (CF) carried out by using pulsed muons at UTMSL/KEK, a direct knowledge of -sticking probability ( _s) in CF of high density D-T mixture with high T concentration has been obtained by measuring a characteristic muonic X-ray from the () atoms (central energy of 8.2 keV with a correct Doppler broadening). Combining with the recent X-ray measurements in (d) to³He and⁴He impurities, new insight is now obtained for the detailed background structure in the X-ray spectrum, suggesting the future direction for the X-ray measurements.