The design and use of nuclear orientation thermometers employing54Mn and60Co nuclei in ferromagnetic hosts

Berglund, P.; Collan, H.; Ehnholm, Gösta; Gylling, R.G.; Lounasmaa, O. V.

doi:10.1007/bf00628318

Cited by 55 publications

(11 citation statements)

References 18 publications

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“…rne is the characteristic time for the energy flow out of the nuclear spin system and is usually called the spin-lattice relaxation time r~ defined at high temperatures by the change of the difference in the inverse temperatures of conduction electrons and nuclei. Within the high temperature approximation zij is defined by dt (3) where i, j= n, e denote the system under consideration, i.e. nuclei and electrons.…”

Section: Heat Flow Equationsmentioning

confidence: 99%

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Heat flow between nuclei and conduction electrons in metals at very low temperatures

Eska

1992

J Low Temp Phys

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Magnetic fieM and thermal gradients not only affect the heat flow between different parts of metallic samples but can also lead to anomalies in the observed energy transport between the electronic and nuclear energy reservoirs. Nuclear spin-lattice relaxation is considered in conditions of applied fieM and temperature such that the contribution of nuclear spins to the heat capacity dominates by far that of the electrons. The model presented is discussed with respect to recent steady state heat flow experiments on copper at submillikelvin temperatures in which a non-Korringa like, anomalously weak coupling between electrons and nuclei was observed. We show that in heat flow experiments at sufficiently low conduction electron temperatures, T~, when thermal gradients are present in the sample, the apparent Korringa constant takes the form tr = too (1 + ~(kT~) -I ) where ~ depends on the heat current and the nuclear heat capacity, too is the actual Korringa constant, and K is the thermal heat conductance of copper which in part depends on the applied field Bo as 1 2Bo assuming that the Wiedemann-Franz law holds. In fact, a BoTe dependence was reported for the anomalous nuclear spin electron coupling which we therefore conclude couM be explained by the finite thermal conductivity in an inhomogeneously heated sample. From a quantitative comparison of our model and the reported tr values, K wouM have to be one order of magnitude smaller than that expected for the used sample of high purity. Difficulties in comparing the over-simplified model with a real experiment are discussed and a comment concerning the effect of impurities in Pt-NMR thermometry at very low temperatures is given.

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Section: Heat Flow Equationsmentioning

confidence: 99%

“…[3][4][5] strong magnetic field gradients exist in *Permanent address: Physikalisches Institut, Universit/it Bayreuth, D-8580 Bayreuth, Germany.…”

Section: Introductionmentioning

confidence: 99%

Heat flow between nuclei and conduction electrons in metals at very low temperatures

Eska

1992

J Low Temp Phys

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“…Later work using this nucleus employed iron, nickel, and cobalt hosts, 111 while most of the recent work has used either an iron host 1 o6.112.113 or a nickel host. 114 In addition, two Kondo systems, (Cu5'~Mn) 115'116 and (Zn54Mn), 117'118 have been investigated for their possible thermometric value. The advantage of these is that below the Kondo temperature the field at the nucleus depends strongly on the applied field, thus their useful temperature range may be extended as compared to the fixed temperature range of normal anisotropy thermometry.…”

Section: Manganese-54mentioning

confidence: 99%

Review paper: Recent advances in thermometry below 300 mK

et al. 1975

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“…A nucleus of spin I and magnetic moment ju has the degeneracy of its 21+1 hyperfine energy levels re The effective magnetic field acting on the nuclei is the sum of external applied field and hyperfine magnetic field which is a result of the electronic system's response to the external field; this can be written as § eff = Bapp * Bhf • (45) The energy separation between levels is AE = >(8 eff /l (46) as each level's spin has a distinct orientation with respect to the direction of applied magnetic field.…”

Section: "»30mentioning

confidence: 99%

Hyperfine enhanced nuclear magnetic cooling in PrCu$sub 6$

Swinehart¹,

Weyhmann²

1973

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The design and use of nuclear orientation thermometers employing54Mn and60Co nuclei in ferromagnetic hosts

Cited by 55 publications

References 18 publications

Heat flow between nuclei and conduction electrons in metals at very low temperatures

Heat flow between nuclei and conduction electrons in metals at very low temperatures

Review paper: Recent advances in thermometry below 300 mK

Hyperfine enhanced nuclear magnetic cooling in PrCu$sub 6$

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