Radio-frequency muon spin resonance (RFμSR) experiments on condensed matter

Scheuermann, R.; Schimmele, L.; Schmidl, J.; Major, J.; Herlach, D.; Scott, Christopher A.

doi:10.1007/bf03161981

Cited by 13 publications

(6 citation statements)

References 29 publications

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“…Formation of Mu@C 60 is certainly epithermal 78 . Finalstate analysis by RF µSR shows no sign of any interconversion between the two paramagnetic species, nor of any significant ionic Mu + or other diamagnetic fraction (Scheuermann et al 1997b).…”

Section: And C 70mentioning

confidence: 89%

“…Ionization of bond-centred muonium, BC 0 → BC + + e c , occurs in Si in the temperature range around 150 K, the ionization or activation energy of 0.21 ± 0.01 eV defining the depth of a donor level below the conduction band edge. Contemporary measurements by Scheuermann et al (1995Scheuermann et al ( , 1997aScheuermann et al ( , 1997b, also from the growth of the Mu + signal by RF resonance final state analysis, gave the value as 0.19 eV but direct measurement of the ionization rate, from lifetime broadening of the parent Mu 0 BC spectrum, has lately corroborated the much quoted value of 0.21 eV (Fan et al 2008(Fan et al , 2009b 39 . The corresponding donor depth for H in Si is 0.18 ± 0.02 eV, as determined from deep level transient spectroscopy (DLTS) by the Aarhus group (Holm et al 1991, Bech Nielsen 1994, Bonde Nielsen et al 1999.…”

Section: Electrical Activity In Siliconmentioning

confidence: 93%

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Muonium as a model for interstitial hydrogen in the semiconducting and semimetallic elements

2009

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Although the interstitial hydrogen atom would seem to be one of the simplest defect centres in any lattice, its solid state chemistry is in fact unknown in many materials, not least amongst the elements. In semiconductors, the realization that hydrogen can profoundly influence electronic properties even as a trace impurity has prompted its study by all available means-but still only in the functionally important or potentially important materials-for the elements, Si, Ge and diamond. Even here, it was not studies of hydrogen itself but of its pseudo-isotope, muonium, that first provided the much needed microscopic pictures of crystallographic site and local electronic structure-now comprehensively confirmed by ab initio computation and such data as exists for monatomic, interstitial hydrogen centres in Si. Muonium can be formed in a variety of neutral paramagnetic states when positive muons are implanted into non-metals. The simple trapped atom is commonly only metastable. It coexists with or reacts to give defect centres with the unpaired electron in somewhat more extended orbitals. Indications of complete delocalization into effective mass states are discussed for B, α-Sn, Bi and even Ge, but otherwise all the muonium centres seen in the elemental semiconductors are deep and relatively compact. These are revealed, distinguished and characterized by µSR spectroscopy-muon spin rotation and resonance informing on sites and spin-density distributions, muon spin relaxation on motional dynamics and charge-state transitions.This Report documents the progress of µSR studies for all the semiconductors and semimetals of the p-block elements, Groups III-VI of the Periodic Table . The striking spectra and originally unanticipated results for Group IV are for the most part well known but deserve summarizing and updating; the sheer diversity of muonium states found is still remarkable, especially in carbon allotropes. The interplay of crystallographic site and charge state in Si and Ge at high temperatures, or under illumination, reflects the capture and loss of charge carriers that should model the electrical activity of monatomic hydrogen but still challenges theoretical descriptions. Spin-flip scattering of conduction electrons by the paramagnetic centres is revealed in heavily doped n-type material, as well as some modification of the local electronic structures. The corresponding spectroscopy for the solid elements of Groups III, V and VI is rather less well known and is reviewed here for the first time; a good deal of previously unpublished data is also included. Theoretical expectations and computational modelling are sparse, here. Recent results for B suggest a relatively shallow centre with molecular character; P and As show deeper quasi-atomic states, but still with substantial overlap of spin density onto surrounding host atoms. Particular attention is paid to the chalcogens. Muonium centres in Te show charge-state transitions already around room temperature; the identification of those in S and Se has been compli...

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Section: And C 70mentioning

confidence: 89%

Section: Electrical Activity In Siliconmentioning

confidence: 93%

Muonium as a model for interstitial hydrogen in the semiconducting and semimetallic elements

2009

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“…8,9 Earlier work using RF-SR combined with illumination has shown that photoexcitation has a strong effect on the spin dynamics of implanted muons in Si/Ge. 10 While continuous effort has been devoted to studies of this kind using the time-integrated techniques, 28,29 we have shown that time-differential SR technique may in fact be a more useful approach for the detailed investigation of slow dynamics under photoexcitation. 11 In general one needs delayed-resonance techniques ͑where the RF pulse is irradiated some time after the initial spin relaxation͒ to distinguish between the initial spin relaxation and that in the final state only by RF-SR.…”

Section: Discussionmentioning

confidence: 99%

Charge dynamics of muonium centers in Si revealed by photoinduced muon spin relaxation

2003

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Muonium dynamics in crystalline Si has been studied in both p-type and n-type samples using the muon spin-relaxation technique combined with photoexcitation. Controlling the excess carrier density in this way has revealed the dynamics of charge-exchange cycles and transfer processes involving Mu BC 0/ϩ and Mu T Ϫ/0 . In particular, photoexcitation has provided access to processes involving hole capture not attained by conventional experimental techniques. As a consequence, strong evidence was found for the delayed formation of electrically inactive muonium states in both types of Si, suggesting a process of diffusion-limited direct interaction of muonium with dopant impurities ͑i.e., muonium passivation͒.

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“…The RF-μSR technique is extensively described in several comprehensive articles, so we shall not provide extensive details but refer the reader to these previous publications. − The Hamiltonian for the 3-spin 1 / 2 system of the muon, electron, and methylene proton with isotropic hyperfine couplings in an externally applied magnetic field B 0 is given by Ĥ = A μ Ŝ normale · Î μ + A normalp Ŝ normale · Î normalp − γ μ B⃗ 0 · Î μ − γ normalp B⃗ 0 · Î normalp where Ŝ e , Î μ , and Î p are the spin operators for the electron, muon, and proton, respectively. The Breit–Rabi diagram for a system with hfccs of A μ = 515 MHz and A p =124 MHz, typical values for the C 6 H 6 Mu radical, is shown in Figure .…”

Section: Introductionmentioning

confidence: 99%

Hyperfine Coupling Constants of the Cyclohexadienyl Radical in Benzene and Dilute Aqueous Solution

et al. 2013

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The muon hyperfine coupling constant (Aμ) of the muoniated cyclohexadienyl radical (C6H6Mu) has been directly measured in a 5 mM solution of benzene in water by the radio-frequency muon spin resonance (RF-μSR) technique. The relative shift of Aμ in aqueous solution compared with the value in neat benzene (ΔAμ/Aμ = +0.98(5)% at 293 K) can now be compared directly with theoretical predictions. Application of the RF-μSR method to other dilute systems will provide extremely important information on understanding solvent effects.

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Radio-frequency muon spin resonance (RFμSR) experiments on condensed matter

Cited by 13 publications

References 29 publications

Muonium as a model for interstitial hydrogen in the semiconducting and semimetallic elements

Muonium as a model for interstitial hydrogen in the semiconducting and semimetallic elements

Charge dynamics of muonium centers in Si revealed by photoinduced muon spin relaxation

Hyperfine Coupling Constants of the Cyclohexadienyl Radical in Benzene and Dilute Aqueous Solution

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