skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Precise measurement of α K and α T for the 109.3-keV M 4 transition in Te 125 : Test of internal-conversion theory

Authors:
; ; ; ; ; ;
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1361224
Grant/Contract Number:
FG03-93ER40773
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Physical Review C
Additional Journal Information:
Journal Volume: 95; Journal Issue: 6; Related Information: CHORUS Timestamp: 2017-06-02 22:10:53; Journal ID: ISSN 2469-9985
Publisher:
American Physical Society
Country of Publication:
United States
Language:
English

Citation Formats

Nica, N., Hardy, J. C., Iacob, V. E., Werke, T. A., Folden, C. M., Ofodile, K., and Trzhaskovskaya, M. B. Precise measurement of α K and α T for the 109.3-keV M 4 transition in Te 125 : Test of internal-conversion theory. United States: N. p., 2017. Web. doi:10.1103/PhysRevC.95.064301.
Nica, N., Hardy, J. C., Iacob, V. E., Werke, T. A., Folden, C. M., Ofodile, K., & Trzhaskovskaya, M. B. Precise measurement of α K and α T for the 109.3-keV M 4 transition in Te 125 : Test of internal-conversion theory. United States. doi:10.1103/PhysRevC.95.064301.
Nica, N., Hardy, J. C., Iacob, V. E., Werke, T. A., Folden, C. M., Ofodile, K., and Trzhaskovskaya, M. B. Fri . "Precise measurement of α K and α T for the 109.3-keV M 4 transition in Te 125 : Test of internal-conversion theory". United States. doi:10.1103/PhysRevC.95.064301.
@article{osti_1361224,
title = {Precise measurement of α K and α T for the 109.3-keV M 4 transition in Te 125 : Test of internal-conversion theory},
author = {Nica, N. and Hardy, J. C. and Iacob, V. E. and Werke, T. A. and Folden, C. M. and Ofodile, K. and Trzhaskovskaya, M. B.},
abstractNote = {},
doi = {10.1103/PhysRevC.95.064301},
journal = {Physical Review C},
number = 6,
volume = 95,
place = {United States},
year = {Fri Jun 02 00:00:00 EDT 2017},
month = {Fri Jun 02 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on June 2, 2018
Publisher's Accepted Manuscript

Save / Share:
  • Cited by 1
  • Cited by 5
  • Here, we report 139La and 63Cu NMR investigation of the successive charge order, spin order, and superconducting transitions in superoxygenated La 2CuO 4+y single crystal with stage-4 excess oxygen order at T stage≃290 K. We show that the stage-4 order induces tilting of CuO 6 octahedra below T stage, which in turn causes 139La NMR line broadening. The structural distortion continues to develop far below Tstage, and completes at T charge≃60 K, where charge order sets in. This sequence is reminiscent of the the charge-order transition in Nd codoped La 1.88Sr 0.12CuO 4 that sets in once the low-temperature tetragonalmore » phase is established. We also show that the paramagnetic 63Cu NMR signals are progressively wiped out below T charge due to enhanced low-frequency spin fluctuations in charge-ordered domains, but the residual 63Cu NMR signals continue to exhibit the characteristics expected for optimally doped superconducting CuO 2 planes. This indicates that charge order in La 2CuO 4+y does not take place uniformly in space. In addition, unlike the typical second-order magnetic phase transitions, low-frequency Cu spin fluctuations as probed by 139La nuclear spin-lattice relaxation rate do not exhibit critical divergence at T spin(≃T c) =42 K. These findings, including the spatially inhomogeneous nature of the charge-ordered state, are qualitatively similar to the case of La 1.885Sr 0.115CuO 4, but both charge and spin order take place more sharply in the present case.« less
  • We report comprehensive 77 Se NMR measurements on a single crystalline sample of the recently discovered FeSe-based high-temperature superconductor K x Fe 2 - y Se 2 ( T c = 33 K) in a broad temperature range up to 290 K. Despite deviations from the stoichiometric KFe 2 Se 2 composition, we observed 77 Se NMR line shapes as narrow as 4.5 kHz under a magnetic field applied along the crystal c axis, and found no evidence for co-existence of magnetic order with superconductivity. On the other hand, the 77 Se NMR line shape splits into two peaks withmore » equal intensities at all temperatures when we apply the magnetic field along the ab plane. This suggests that K vacancies may have a superstructure and that the local symmetry of the Se sites is lower than the tetragonal fourfold symmetry of the average structure. This effect might be a prerequisite for stabilizing the s ± symmetry of superconductivity in the absence of the hole bands at the Brillouin zone center. From the increase of NMR linewidth below T c induced by the Abrikosov lattice of superconducting vortices, we estimate the in-plane penetration depth λ ab ~ 290 nm and the carrier concentration n e ~ 1 × 10 + 21 cm - 3 . Our Knight shift 77 K data indicate that the uniform spin susceptibility decreases progressively with temperature, in analogy with the case of FeSe ( T c ~ 9 K) as well as other FeAs high- T c systems. The strong suppression of 77 K observed immediately below T c for all crystal orientations is consistent with a singlet pairing of Cooper pairs. We do not however observe the Hebel-Slichter coherence peak of the nuclear spin-lattice relaxation rate 1 / T 1 immediately below T c , expected for conventional BCS s-wave superconductors. In contrast with the case of FeSe, we do not observe evidence for an enhancement of low-frequency antiferromagnetic spin fluctuations near T c in 1 / T 1 T . Instead, 1 / T 1 T exhibits qualitatively the same behavior as overdoped non-superconducting Ba(Fe 1 - x Co x ) 2 As 2 with x ~ 0 . 14 or greater, where hole bands are missing in the Brillouin zone center. We will discuss the implications of our results on the unknown mechanism of high-temperature superconductivity in FeSe and FeAs systems.« less