Exchange interaction of isolated Eu2+ ions in La at high temperatures

Barth, H. J.; Nishiyama, K.; Riegel, D.

doi:10.1016/0375-9601(80)90721-5

Cited by 20 publications

(8 citation statements)

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“…In a recent hyperfine interaction study [6] with 139La(12C, xn) reactions the 14SEu isomer was populated and its g-factor was reported as g= +0.680 (5). However, in this study the isomeric half life was measured as 170(20)ns, and several higher energy 7-transitions, which we do not observe, were attributed to the isomer decay whereas the intense 396 and 476 keV lines were not recognized.…”

Section: Discussioncontrasting

confidence: 79%

“…Previously, all that was known about 148Eu was its ground state spin which in an atomic beam study [5] was measured as 5, and negative parity was inferred from shell model argu- [6] determined the g-factor of a 14SEu isomer with unknown spin and excitation. Previously, all that was known about 148Eu was its ground state spin which in an atomic beam study [5] was measured as 5, and negative parity was inferred from shell model argu- [6] determined the g-factor of a 14SEu isomer with unknown spin and excitation.…”

Section: Introductionmentioning

confidence: 99%

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The 235 ns 9+ isomer in 63 148 Eu85

et al. 1981

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Section: Discussioncontrasting

confidence: 79%

Section: Introductionmentioning

confidence: 99%

The 235 ns 9+ isomer in 63 148 Eu85

et al. 1981

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“…An analogous comparison of T/ 1 for Pr in liquid La with the ESR rate for LaGd (see Ref. 6) yields |#J C | = 0.08 and \NJ sf \=0A for LaVv and \NJ sf | =0.028 for LaGd. The analysis in terms of the J sf exchange is shown to be highly unreasonable for the Nd, Pr, and Ce systems, since J sf is expected to be nearly constant throughout the RE series.…”

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confidence: 91%

“…2), and Gd (Ref. 6) in liquid Sn at 900 K, respectively. If one analyzes these T/ 1 rates in terms of the classical J sf exchange, T J~l = Anh~1[(g J -l)NJ sf \ 2 xk B T, the coupling \NJ sf | is found to be 0.57, 0.16, and 0.013 for Ce, Nd, and Gd in liquid Sn, respectively.…”

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4fSpin Dynamics of Isolated Nd, Pr, and Ce Ions in Simple Metals

Riegel

1982

Phys. Rev. Lett.

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The 4/spin dynamics of extremely dilute Nd, Pr, and Ce ions in liquid metals are microscopically observed by the time-differential perturbed -y-ray distribution method. The 4/spin rates are dominated by strong mixing exchange interaction in all systems investigated, which is, e.g., reflected by a Kondo-like behavior for Nd systems. The pressuredriven valence transition in dilute LaVv alloys is probably of the 4/ 2 -4/" 1 type. One has to expect that 4/instabilities might occur for all light rare-earth ions in appropriate systems.PACS numbers: 75.20.Hiy71.70.Gm, 76.30.Kg, 76.80.+ y At present, there exists deep theoretical uncertainty in the description of intermediate valence (IV) phenomena (for a review, see Lawrence, Riseborough, and Parks 1 ) and their relation to less pronounced 4/ configurational instabilities which usually are described in terms of Kondo theories (for a review, see Maple, DeLong, and Sales 2 ). Hitherto, configurational instabilities (IV and/or Kondo effect) have been found for metallic systems containing Ce, Pr, Sm, Eu, Tm, and Yb ions. In the center of current interest is the behavior of light rare-earth (RE) ions in metals, as reflected by a large number of studies 1,2 in Ce, Sm, and Eu systems and some investigations 2,3 in Pr systems. The interpretation of previous results on Nd systems (e.g., Barberis et al.,4 DeLong et al.f and Schmid and Umlauf 5 ) has remained in an unsatisfying stage.Since the 4/ linewidth is perhaps the most fundamental parameter for both IV and Kondo-like instabilities in dilute and concentrated rare-earth systems, the present work aimed to study the 4/ spin dynamics of isolated Nd, Pr, and Ce ions in simple metals. Accurate measurements of this elusive quantity are possible by the time-differential perturbed angular y-ray distribution method (TDPAD) 6 " 8 following nuclear reactions. The choice of liquid hosts allows for a direct extraction of the 4/ spin relaxation rate Tj' 1 from the nuclear relaxation times r N observed. Furthermore, the influence of crystal electric field (CEF) effects on the magnetic response of the liquid systems seems to be negligible, which can be formulated as k B T large compared with the CEF splitting A. For solid metallic Nd, Pr, and Ce systems A/& B is -100 K. 2 " 8 Additionally, the liquid state permits measurements in alloys over a wide range of concentration. Of particular importance is the possibility to compare the 4/ spin dynamics for isolated Nd and Ce ions in the same liquid hosts.The Nd, Pr, and Ce Systems were produced by the heavy-ion reactions 122 Sn( 20 Ne,4w) 138 Nd, 139 La(a,4w) 139 Pr, and 124 Sn( 16 0,4w) 136 Ce (see Barth et alj), respectively. Liquid natural La, liquid Sn, and liquid SnAu and SnBi alloys were used as targets which were enriched in 122 Sn for the Nd systems and in 124 Sn for the SnBiCe systems. The concentration of the RE ions produced was smaller than 1 ppm. Pulsed 20 Ne, le O, and a beams were provided by the VICKSI accelerator at the Hahn-Meitner-Institut, Berlin. By these reactions the 10 +...

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