Nuclear Spin Relaxation in Transition Metals; Core Polarization

Yafet, Y.; Jaccarino, V.

doi:10.1103/physrev.133.a1630

Cited by 308 publications

(85 citation statements)

References 15 publications

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“…Cu-Mn) was studied quite extensively, both theoretically [85][86][87][88][89][90][91][92][93] and experimentally. [94][95][96][97][98][99][100][101][102][103][104][105][106][107][108][109][110] . The description of spin relaxation in dilute alloys has certain specific features as compared with the homogeneous systems.…”

Section: Host Nuclear Spin Diffusion In Dilute Alloysmentioning

confidence: 99%

Statistical Theory of Spin Relaxation and Diffusion in Solids

Kuzemsky

2006

J Low Temp Phys

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A comprehensive theoretical description is given for the spin relaxation and diffusion in solids. The formulation is made in a general statistical-mechanical way. The method of the nonequilibrium statistical operator (NSO) developed by Zubarev is employed to analyze a relaxation dynamics of a spin subsystem. Perturbation of this subsystem in solids may produce a nonequilibrium state which is then relaxed to an equilibrium state due to the interaction between the particles or with a thermal bath (lattice). The generalized kinetic equations were derived previously for a system weakly coupled to a thermal bath to elucidate the nature of transport and relaxation processes. In this paper, these results are used to describe the relaxation and diffusion of nuclear spins in solids. The aim is to formulate a successive and coherent microscopic description of the nuclear magnetic relaxation and diffusion in solids. The nuclear spin-lattice relaxation is considered and the Gorter relation is derived. As an example, a theory of spin diffusion of the nuclear magnetic moment in dilute alloys (like Cu-Mn) is developed.It is shown that due to the dipolar interaction between host nuclear spins and impurity spins, a nonuniform distribution in the host nuclear spin system will occur and consequently the macroscopic relaxation time will be strongly determined by the spin diffusion. The explicit expressions for the relaxation time in certain physically relevant cases are given.

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Section: Host Nuclear Spin Diffusion In Dilute Alloysmentioning

confidence: 99%

Statistical Theory of Spin Relaxation and Diffusion in Solids

Kuzemsky

2006

J Low Temp Phys

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“…+y The nuclear spin-lattice relaxation in metals arises predominantly from the magnetic hyperfine interaction between the nuclear spins and the conduction electrons. It gives information on the density of states at the Fermi energy and the magnitude of low frequency spin fluctuations [1 -3].The interpretation of the relaxation is complicated in transition metals by the fact that several relaxation mechanisms can contribute, but only the total relaxation rate R is usually measured: According to the type of the responsible hyperfine interaction, R can be subdivided into an orbital (R o ), a Fermi-contact (R c ), a spin-dipolar (R sd ), a core-polarization (R cp ), and a quadrupolar (R q ) contribution [3,4]. The first four contributions represent together the magnetic relaxation rate R m .…”

mentioning

confidence: 99%

“…The interpretation of the relaxation is complicated in transition metals by the fact that several relaxation mechanisms can contribute, but only the total relaxation rate R is usually measured: According to the type of the responsible hyperfine interaction, R can be subdivided into an orbital (R o ), a Fermi-contact (R c ), a spin-dipolar (R sd ), a core-polarization (R cp ), and a quadrupolar (R q ) contribution [3,4]. The first four contributions represent together the magnetic relaxation rate R m .…”

mentioning

confidence: 99%

Electric Quadrupolar Contribution to the Nuclear Spin-Lattice Relaxation of Ir in Fe

Seewald

Zech

et al. 2002

Phys. Rev. Lett.

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We report on the first quantitative determination of the electric quadrupolar contribution to the nuclear spin-lattice relaxation in a transition metal. For 186 Ir and 189 Ir in Fe we have determined the magnetic and the electric quadrupolar part of the relaxation for magnetic fields between 0.01 and 2 T. The quadrupolar part gives information on the role of the orbital motion of the electrons for the relaxation process. Our results prove that the unexpected high relaxation rates in Fe and their magnetic field dependence are due to a nonorbital relaxation mechanism. DOI: 10.1103/PhysRevLett.88.057601 PACS numbers: 76.60.Es, 75.50.Bb, 76.80. +y The nuclear spin-lattice relaxation in metals arises predominantly from the magnetic hyperfine interaction between the nuclear spins and the conduction electrons. It gives information on the density of states at the Fermi energy and the magnitude of low frequency spin fluctuations [1 -3].The interpretation of the relaxation is complicated in transition metals by the fact that several relaxation mechanisms can contribute, but only the total relaxation rate R is usually measured: According to the type of the responsible hyperfine interaction, R can be subdivided into an orbital (R o ), a Fermi-contact (R c ), a spin-dipolar (R sd ), a core-polarization (R cp ), and a quadrupolar (R q ) contribution [3,4]. The first four contributions represent together the magnetic relaxation rate R m . R q is due to the electric hyperfine interaction and arises from electric field gradient fluctuations at the nuclear site.The various contributions involve quite different electronic excitations: R c , for example, is connected to spin flips of s electrons; R o and R q are connected to orbital momentum changes of p or d electrons. A separate determination would, therefore, give valuable information on the relaxation process. Such information is especially desirable since experiment and theory are in serious disagreement for several transition metal systems [5,6].In this situation, one can make use of two special features of R q : R q can be determined separately and it is so closely related to R o that R o can be estimated from R q [4,7]. This offers the unique possibility to decompose experimentally the relaxation into an orbital and a nonorbital part.This possibility is used here for the first time. It is used to study the origin of two still unsolved problems in the nuclear spin-lattice relaxation in Fe: (i) The relaxation rates are usually larger than predicted by ab initio calculations. This effect is especially prominent and well documented for the 5d impurities in Fe [6]. (ii) For magnetic fields below 1 T there is a so far unexplained magnetic field dependence due to which the relaxation in zero field is typically 3 to 10 times faster than at high fields [8][9][10].This work is also the first experimental determination of R q in a transition metal, although the presence of this contribution to the relaxation in transition metals is meanwhile well established in the theoretical wor...

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“…The d-electrons at the Fermi surface are coupled to the nuclei via the inner shell s-electrons and can take up energy from the nuclear spin system. Yafet and Jaccarino (24) have derived an expression for T^. They give and (24).…”

Section: Obata (28) Has Shown That the Orbital Term In Equationmentioning

confidence: 99%

“…Thus, in a magnetic field, a shift of the reso nance occurs. Yafet and Jaccarino (24) have given, in the tight binding limit, the following expression for the relative shift due to core polarization % = <lcp^p(o)l^> (10) where is the d-band susceptibility per volume…”

Section: Knight Shiftmentioning

confidence: 99%

A magnetic resonance study of the vanadium-chromium system and of the Néel temperatures of the chromium-rich alloys

Graham

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Nuclear Spin Relaxation in Transition Metals; Core Polarization

Cited by 308 publications

References 15 publications

Statistical Theory of Spin Relaxation and Diffusion in Solids

Statistical Theory of Spin Relaxation and Diffusion in Solids

Electric Quadrupolar Contribution to the Nuclear Spin-Lattice Relaxation of Ir in Fe

A magnetic resonance study of the vanadium-chromium system and of the Néel temperatures of the chromium-rich alloys

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