Effect of Coulomb Interaction on the X-Ray Magnetic Circular Dichroism Spin Sum Rule in 3<i><i>d</i></i>Transition Elements

Teramura, Yoshiki; Tanaka, A.; Jo, Takeo

doi:10.1143/jpsj.65.1053

Cited by 194 publications

(157 citation statements)

References 13 publications

Supporting

Mentioning

148

Contrasting

Unclassified

Order By: Relevance

“…We have assumed that the contribution of the dipole operator term T z in the spin sum rule is negligibly small because the Mn site in bulk CMG has T d symmetry. 27 Since the L 3 and L 2 regions in Mn L 2,3 XAS and XMCD overlap due to the strong exchange interaction between the Mn 2p core hole and the Mn 3d electrons, we have divided the obtained spin magnetic moment by the correction factor 0.68 given by Teramura et al 38 We have assumed a 3d hole number (n h ) of 4.5 for Mn 20,24,27 on the basis of the band structure calculations. The spin magnetic moment m spin (Mn) thus deduced is plotted as a function of β in Fig.…”

Section: Resultsmentioning

confidence: 99%

Effects of off-stoichiometry on the spin polarization at the Co2MnβGe0.38/MgO interfa

et al. 2012

View full text Add to dashboard Cite

We have studied the electronic and magnetic states of Mn and Co atoms at the Co 2 Mn β Ge 0.38 (CMG)/MgO (β = 0.67-1.8) interfaces, which constitute CMG/MgO/CMG magnetic tunnel junctions, by means of x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroisms (XMCDs) at the Mn and Co L 2,3 edges and compared the deduced Co and Mn magnetic moments by the density-functional calculations with the coherent potential approximation (CPA). As the Mn content β increased, the intensity of Mn L 2,3 XMCD decreased, in agreement with the result of the CPA calculation, which showed the resultant reduction of charges and spin moment on Mn atoms because of the delocalization of Mn 3d electrons with increasing β. The Co spin magnetic moment for all the samples increased with decreasing β, again consistent with the present calculation and the previous density-functional calculation by Picozzi et al. that the Co Mn antisite has a larger magnetic moment than that of Co atoms at the regular sites and reduces the spin polarization at the Fermi level and hence the tunnel magnetoresistance ratio.

show abstract

Section: Resultsmentioning

confidence: 99%

Effects of off-stoichiometry on the spin polarization at the Co2MnβGe0.38/MgO interfa

et al. 2012

View full text Add to dashboard Cite

show abstract

“…The effective spin sum rule has been theoretically simulated and tested by Teramura et al 7 They calculated the expectation values of the effective spin ͗SE z ͘ and compared them with simulated effective spin sum-rule values ͓SE z sum ͔. van der Laan et al 8 used the ratio of the G 1 ͑pd͒ Slater integral and the core hole spin-orbit coupling to estimate the purity of the L 2 and L 3 edges and as such the accuracy of the effective spin-orbit sum rule.…”

Section: ͑⍀͒D⍀ ͑1͒mentioning

confidence: 99%

Accuracy of the spin sum rule in XMCD for the transition-metalLedges from manganese to copper

2009

View full text Add to dashboard Cite

The effective spin sum rule is widely used in the quantitative analysis of x-ray magnetic circular dichroism spectra. Here, this important, though imperfect, sum rule is reviewed with a detailed analysis of the various sources for errors and deviations. The simulations confirm that the final state effects of the core level spin-orbit coupling and the core-valence exchange interactions ͑multiplet effects͒ are linearly related with the effective spin sum-rule error. Within the charge transfer multiplet approach, we have analyzed these effects, in combination with the interactions affecting the magnetic ground state, including the crystal field strength, the charge transfer effects, the exchange ͑magnetic͒ field, and the 3d spin-orbit coupling. We find that for the late transition-metal systems, the error in the effective spin moment is between 5% and 10%, implying that for covalent and/or metallic systems the effective spin sum rule is precise to within 5-10 %. The error for 3d 5 systems is ϳ30% and for 3d 4 systems, the error is very large, implying that, without further information, the derived effective spin sum-rule values for 3d 4 systems have no meaning.

show abstract

“…2 In particular, there is increasing activity regarding 3d−4f single-molecule magnets, and numerous species have been reported so far. 3,4 The complete understanding of their magnetic behavior is, however, lagging behind, and for instance, the key to the necessary ingredients that mediate properties such as slow relaxation of magnetization in 3d−4f clusters is still missing.…”

Section: ■ Introductionmentioning

confidence: 99%

“…13 Recently, we reported the first examples of 3d−4f clusters assembled by unsupported fluoride bridges. 11b,14 Here we report the synthesis and the structural characterization of a novel series of methoxide-bridged clusters: [Cr III (phen) 2 (μ-MeO) 2 Ln(NO 3 ) 4 ]·xMeOH with Ln = Nd (1), Tb (2), and Dy (3). As for the previously reported, fluoride-bridged systems, the chromium precursor in the present study is the robust cis-[Cr III F 2 (phen) 2 ] + ion.…”

Section: ■ Introductionmentioning

confidence: 99%

“…In such a situation it has been shown that the sum rules can be subject to large errors. It has been demonstrated that as a remedy, a spin correction factor can be obtained from ligand-field multiplet calculations [2]. The values for the <S z > expectation value found from sum rules then have to be corrected by this factor, defined as <S z > = f SC · <S z,SR >, where <S z,SR > denotes the expectation value of the spin z component determined using sum rules.…”

mentioning

confidence: 99%

See 1 more Smart Citation

X-ray Magnetic Circular Dichroism (XMCD) Study of a Methoxide-Bridged Dy^III–Cr^III Cluster Obtained by Fluoride Abstraction from cis-[Cr^IIIF₂(phen)₂]⁺

et al. 2012

View full text Add to dashboard Cite

An isostructural series of dinuclear chromium-(III)−lanthanide(III) clusters is formed by fluoride abstraction of cis-[CrF 2 (phen) 2 ] + by Ln 3+ resulting in LnF 3 and methoxide-bridged Cr−Ln clusters (Ln = Nd (1), Tb (2), Dy (3 )) of formula [Cr I I I (phen) 2 ( μ -MeO) 2 Ln-(NO 3 ) 4 ]·xMeOH (x = 2−2.73). In contrast to fluoride, methoxide bridges in a nonlinear fashion, which facilitates chelation. For 3, X-ray magnetic circular dichroism (XMCD) provides element-specific magnetization curves that are compared to cluster magnetization and susceptibility data acquired by SQUID magnetometry. The combination of XMCD and SQUID is able to resolve very small magnetic coupling values and reveals a weak Cr III −Dy III coupling of j = −0.04(3) cm −1 . The Dy III ion has a ground-state Kramers doublet of m J = ±13/2, and the first excited doublet is found to be m J = ±11/2 at an energy of δ = 57(21) cm −1 . The Cr III ion exhibits a uniaxial anisotropy of D Cr = −1.7(1.0) cm −1 . Further, we observe that a weak anisotropic coupling of dipolar origin is sufficient to model the data, suggesting that methoxide bridges do not play a significant role in the magnetic coupling for the present systems. ■ INTRODUCTIONMolecular nanomagnets 1 have attracted a lot of interest because of their fascinating properties and their prospects in future applications in quantum information processing and molecular spintronics. 2 In particular, there is increasing activity regarding 3d−4f single-molecule magnets, and numerous species have been reported so far. 3,4 The complete understanding of their magnetic behavior is, however, lagging behind, and for instance, the key to the necessary ingredients that mediate properties such as slow relaxation of magnetization in 3d−4f clusters is still missing. 5 Difficulties in finding this key are aggravated by the complexity of the magnetism of 4f ions with orbital contribution to their ground state. 6 In particular, it is difficult to obtain precise values of the magnetic exchange coupling between 3d and 4f ions: In 3d clusters, this information can be readily extracted from dc magnetic susceptibility measurements; however, the large anisotropy splittings resulting from the 4f ligand-field states can strongly influence the temperature dependence of the magnetic susceptibility. Hence, exchange coupling deduced solely from susceptibility data may be subject to large uncertainties. The problem can be circumvented by using additional methods such as diamagnetic substitution, 7,8 electron paramagnetic resonance, 8 or inelastic neutron scattering studies. 9 X-ray magnetic circular dichroism 10 (XMCD) is able to obtain absolute values of element-specific magnetization, which can in turn be exploited to obtain a sensitive measurement of very small magnetic coupling values, and thus it is among the techniques of choice to quantify such coupling in 3d−4f clusters. 11 Precise knowledge about the magnetic exchange coupling is the prerequisite for obtaining its dependence along the homologous series ...

show abstract

Effect of Coulomb Interaction on the X-Ray Magnetic Circular Dichroism Spin Sum Rule in 3dTransition Elements

Cited by 194 publications

References 13 publications

Effects of off-stoichiometry on the spin polarization at the Co2MnβGe0.38/MgO interfa

Effects of off-stoichiometry on the spin polarization at the Co2MnβGe0.38/MgO interfa

Accuracy of the spin sum rule in XMCD for the transition-metalLedges from manganese to copper

X-ray Magnetic Circular Dichroism (XMCD) Study of a Methoxide-Bridged Dy^III–Cr^III Cluster Obtained by Fluoride Abstraction from cis-[Cr^IIIF₂(phen)₂]⁺

Contact Info

Product

Resources

About

Effect of Coulomb Interaction on the X-Ray Magnetic Circular Dichroism Spin Sum Rule in 3dTransition Elements

Cited by 194 publications

References 13 publications

Effects of off-stoichiometry on the spin polarization at the Co2MnβGe0.38/MgO interfa

Effects of off-stoichiometry on the spin polarization at the Co2MnβGe0.38/MgO interfa

Accuracy of the spin sum rule in XMCD for the transition-metalLedges from manganese to copper

X-ray Magnetic Circular Dichroism (XMCD) Study of a Methoxide-Bridged DyIII–CrIII Cluster Obtained by Fluoride Abstraction from cis-[CrIIIF2(phen)2]+

Contact Info

Product

Resources

About

X-ray Magnetic Circular Dichroism (XMCD) Study of a Methoxide-Bridged Dy^III–Cr^III Cluster Obtained by Fluoride Abstraction from cis-[Cr^IIIF₂(phen)₂]⁺