Toward the Computational Prediction of Muon Sites and Interaction Parameters

Bonfà, Pietro; Renzi, R. De

doi:10.7566/jpsj.85.091014

Cited by 38 publications

(29 citation statements)

References 115 publications

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“…To confirm this, latticesum calculations of rms nuclear dipolar fields have been carried out for two candidate muon sites in the Sr 2 IrO 4 crystal structure: (a) halfway between nearest-neighbor O(1) sites in the Ir/Rh-O plane, and (b) halfway between nearest-neighbor O(1)-O(2) sites [49]. Although muon stopping sites in Sr 2 IrO 4 have not been determined experimentally or calculated ab initio [50], in oxides they are typically close to O 2− ions; fields at these sites can be taken as representative.…”

Section: Static Relaxation In Zfmentioning

confidence: 99%

Slow magnetic fluctuations and critical slowing down in Sr2Ir1−xRhxO4

et al. 2020

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Hidden magnetic order in the correlated iridate Sr 2 Ir 1−x Rh x O 4 , x = 0.05 and 0.1, has been studied using muon spin relaxation spectroscopy. In zero field (ZF) and weak longitudinal fields (LFs) ( 2 mT), the muon spin relaxation data indicate that static and dynamic local fields coexist at each muon site, and can be well described by exponentially damped static Lorentzian Kubo-Toyabe functions. The ZF relaxation rate is dominated by the static-field distribution, and a broad relaxation rate maximum at 175 K for x = 0.1 in ZF is attributed to muon diffusion and trapping. For LF 2 mT the static rate is completely decoupled, and the exponential decay is due to dynamic spin fluctuations. The temperature dependencies of the relaxation rates exhibit maxima at 215 K (x = 0.05) and 175 K (x = 0.1), in agreement with previous second harmonic generation and polarized neutron diffraction determinations of transition temperatures to a hidden-order state. The maxima are most likely due to critical slowing down of electronic spin fluctuations. The field dependencies of the dynamic spin fluctuation rates can be well described by the Redfield relation, from which the rms width B rms loc and correlation time τ c of the fluctuating field are obtained. Values of τ c are in the range of 1.5-4 ns for x = 0.1 and shorter than 2 ns for x = 0.05, suggesting an increase with increasing Rh concentration. Values of B rms loc are on the order of 1 mT, consistent with the polarized neutron diffraction cross section.

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Section: Static Relaxation In Zfmentioning

confidence: 99%

Slow magnetic fluctuations and critical slowing down in Sr2Ir1−xRhxO4

et al. 2020

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“…The former quantity, i.e., the ordered magnetic moment, is proportional to the local magnetic field at the μ + site, hereafter indicated as B μ . The proportionality factor can be estimated by means of probabilistic approaches [29,47] or computed exactly once the μ + thermalization site and interaction mechanisms are known [48,49]. However, the temperature dependence for B μ and for the order parameter is the same, which is relevant in order to estimate experimentally the associated critical exponent β for T T c , where T c represents the broadly defined critical temperature [50].…”

Section: A Unusual Behavior For the Magnetic Volume Fraction Of Eu 2mentioning

confidence: 99%

Monopole-limited nucleation of magnetism in Eu2Ir2O7

et al. 2020

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We present an in-depth analysis of muon-spin spectroscopy measurements of Eu 2 Ir 2 O 7 under the effect of the Eu 1-x Bi x isovalent and diamagnetic substitution as well as of external pressure. Our results evidence an anomalous correlation between the magnetic volume fraction and the order parameter only for stoichiometric Eu 2 Ir 2 O 7 , pointing towards highly unconventional properties of the magnetic phase developing therein. We argue that magnetism in Eu 2 Ir 2 O 7 develops based on the nucleation of magnetic droplets at T N , whose successive growth is limited by the need of a continuous generation of magnetic hedgehog monopoles.

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“…To overcome this problem theoretical modeling and computational considerations could be quite helpful and in the ideal situation, it is desirable to reproduce the whole µSR spectrum computationally. 58 Our focus in this paper is also on new methodological developments in this direction. a) Electronic mail: m_goli@ipm.ir b) Electronic mail: sh_shahbazian@sbu.ac.ir From a quantum mechanical viewpoint, muonic molecules may be treated in various ways since one may incorporate muon's kinetic energy operator and the its potential energy terms directly into the molecular Hamiltonian, conceiving it as a quantum particle, or treating it as a clamped particle like the heavy nuclei.…”

Section: Introductionmentioning

confidence: 99%

Two-component density functional theory for muonic molecules: Inclusion of the electron-positive muon correlation functional

Goli,

Shahbazian

2021

Preprint

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It is well-known experimentally that the positively-charged muon and the muonium atom may bind to molecules and solids, and through muon's magnetic interaction with unpaired electrons, valuable information on the local environment surrounding the muon is deduced. Theoretical understanding of the structure and properties of resulting muonic species requires accurate and efficient quantum mechanical computational methodologies. In this paper the two-component density functional theory, TC-DFT, as a first principles method, which treats electrons and the positive muon on an equal footing as quantum particles, are introduced and implemented computationally. The main ingredient of this theory, apart from the electronic exchange-correlation functional, is the electron-muon correlation functional which is foreign to the purely electronic DFT. A Wigner-type local electron-muon correlation functional, termed eµc-1, is proposed in this paper and its capability is demonstrated through its computational application to a benchmark set of organic muonic molecules. The TC-DFT equations containing eµc-1 are not only capable of predicting the muon's binding site correctly but they also reproduce muon's zero-point vibrational energies and the muonic densities much more accurately than the TC-DFT equations lacking eµc-1. Thus, this study set the stage for developing accurate electron-muon functionals, which can be used within the context of the TC-DFT to elucidate the intricate interaction of the positive muon with complex molecular systems.

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Toward the Computational Prediction of Muon Sites and Interaction Parameters

Cited by 38 publications

References 115 publications

Slow magnetic fluctuations and critical slowing down in Sr2Ir1−xRhxO4

Slow magnetic fluctuations and critical slowing down in Sr2Ir1−xRhxO4

Monopole-limited nucleation of magnetism in Eu2Ir2O7

Two-component density functional theory for muonic molecules: Inclusion of the electron-positive muon correlation functional

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