The role of positronium decoherence in positron annihilation in matter

Abstract Co2MnGa is a Weyl semimetal exhibiting giant anomalous Hall and Nernst effects. Using spin-polarized positron annihilation spectroscopy, we examined a Bridgman-grown Co2MnGa single crystal with a nearly perfect L21-ordered structure and a reference Co2MnAl polycrystal with a Mn-Al-disordered B2 structure. We found that a large amount of magnetic vacancies (more than 100 ppm) were included in the Co2MnGa crystal but not the Co2MnAl crystal. We discuss possible reasons for the inclusion of vacancies, the role of vacancies in the development of the ordered structure, and the electronic states associated with the vacancies. Towards the development of Co2MnGa-based devices, the manners for reducing vacancies as well as the influence of vacancies on the electrical transport properties should be considered.

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Deciphering the Role of Charge Compensator in Optical Properties of SrWO4:Eu3+:A (A = Li+, Na+, K+): Spectroscopic Insight Using Photoluminescence, Positron Annihilation, and X-ray Absorption

Inorganic Chemistry ◽

10.1021/acs.inorgchem.7b02780 ◽

2018 ◽

Vol 57 (2) ◽

pp. 821-832 ◽

Cited By ~ 37

Author(s):

Santosh Kumar Gupta ◽

Kathi Sudarshan ◽

Ashok Kumar Yadav ◽

Ruma Gupta ◽

Dibyendu Bhattacharyya ◽

...

Keyword(s):

Optical Properties ◽

Positron Annihilation ◽

X Ray ◽

Charge Compensator ◽

X Ray Absorption

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Point Defects, Dislocations in GaAs and Material Homogeneity

MRS Proceedings ◽

10.1557/proc-104-411 ◽

1987 ◽

Vol 104 ◽

Author(s):

J. C. Bourgoin ◽

H. J. von Bardeleben ◽

H. Lin ◽

D. Stievenard

Keyword(s):

Thermal Analysis ◽

Differential Thermal Analysis ◽

Positron Annihilation ◽

Point Defects ◽

Bulk Gaas ◽

Material Homogeneity

ABSTRACTCombined positron annihilation and differential thermal analysis have shown that, in bulk GaAs materials, dislocations are decorated with vacancy related defects which recombine with As interstitials originating from As clusters. The role of these dislocations, the role of As source of these clusters are described and the consequences on the material homogeneity discussed.

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POSITRON ANNIHILATION IN HIGH Tc SUPERCONDUCTOR Bi-Sr-Ca-Cu-O

Modern Physics Letters B ◽

10.1142/s0217984990001240 ◽

1990 ◽

Vol 04 (15) ◽

pp. 993-997 ◽

Cited By ~ 6

Author(s):

H.C. HUANG ◽

D.H. LI ◽

S.N. ZHENG ◽

A.L. LI ◽

F. CHEN ◽

...

Keyword(s):

Positron Annihilation ◽

Doppler Broadening ◽

High Tc ◽

Positron Annihilation Lifetime ◽

High Tc Superconductor ◽

Superconducting Phases ◽

Temperature Dependences ◽

Long Time

The temperature dependences of the positron annihilation lifetime and Doppler broadening have been measured in the Bi-Sr-Ca-Cu-O superconducting system from 77 to 300 K. The results show the existence of two superconducting phases: Tc=90 K 2212 phase and Tc=107 K 2223 phase, with the latter being dominant. Two anomalies were detected around 145 and 250 K, respectively. The role of long-time sintering and adding Pb and Nb in Bi-Sr-Ca-Cu-O is demonstrated in stabilizing the 2223 phase.

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