4f-band of Ce-compounds in photoexcitation and in low energy phenomena

Sakai, Osamu; Takeshige, Motomu; Harima, Hisatomo; Otaki, Keiichi; Kasuya, T.

doi:10.1016/0304-8853(85)90220-3

Cited by 44 publications

(8 citation statements)

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“…21 This is considered to be due to the strong hybridization, the so-called p-f mixing effect. 22,23 Finally, we comment on the slight dip observed around 30 K in the temperature dependence of present elastic constants. One may think that this is ascribed to the high-lying 4 f states.…”

Section: ͑3͒mentioning

confidence: 64%

Elastic properties of the filled skutterudite compoundNdFe4P12

et al. 2004

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We have performed ultrasonic measurements of the filled skutterudite compound NdFe 4 P 12 to investigate the elastic properties and 4 f ground state of Nd ions split by the crystalline electric-field ͑CEF͒ effect. A pronounced elastic softening towards low temperatures was observed in the temperature dependence of the elastic constants C 11 , (C 11 ϪC 12 )/2, and C 44 . From the present results the CEF ground state of Nd ions and their low-temperature behavior are discussed in connection with the CEF ground state being degenerate with a quadrupolar moment.

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Section: ͑3͒mentioning

confidence: 64%

Elastic properties of the filled skutterudite compoundNdFe4P12

et al. 2004

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“…There are a number of reports of dHvA or SdH effect measurements for RX, and band structure calculations for them have also been performed. [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] These experimental and theoretical studies show that RX compounds have very simple Fermi surfaces. Except for Ce and Yb monopnictides, the Fermi surface topology is same as that of a nonmagnetic reference compound LaSb, which is studied by the dHvA measurements and the band structure calculation in details.…”

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confidence: 99%

“…27,28,35 The CR experiments on RX are interesting due to the following point. Several compounds of RX have large mass enhancement, although the Fermi surfaces are very simple.…”

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confidence: 99%

Cyclotron resonance in rare-earth monopnictides

et al. 2005

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Recently, we have developed equipment which can be used for both cyclotron resonance ͑CR͒ and electron spin resonance ͑ESR͒ measurements for studying f-electron systems. Using this equipment and preparing high-quality single crystals with a residual resistivity ratio of about 500, we have successfully observed CR signals in rare-earth monopnictides RX ͑R =La,Ce,Pr,Gd,X =Sb,Bi͒. The purpose of this paper is to describe the development of our measurement system in detail and to reexamine our recent results of CR measurements on the single crystals of RX. And then, we discuss the origin of mass enhancement in this system by comparing the case of a strongly correlated f-electron system CeSb with the case of a nonmagnetic simple semimetal LaSb. The CR measurements have been performed in the temperature range from 1.4 K to 40 K and in the frequency range from 50 to 190 GHz. We have observed CR signals in LaSb, LaBi, CeSb, PrSb, and GdSb. The cyclotron effective masses m CR * determined by the CR measurements are compared with the masses m QO * estimated by measurements of quantum oscillations and the masses m BC * deduced from band structure calculations. The determined m CR * of LaSb, LaBi, and GdSb is in the range of ͑0.17-0.65͒m 0 . These values are reasonably consistent with the values of m QO * and m BC * . This fact shows that both m CR * and m QO * mainly depend on the band structure if the interaction between conduction electrons and f electrons is negligible. On the other hand, in the case of a strongly correlated f-electron system CeSb, m CR * is in the range of ͑0.26-1.5͒m 0 . These values are much larger than those of m BC * . This finding shows that m CR * , as well as m QO * , is considerably enhanced in CeSb. Our results indicate that the interband interaction is important for the mass enhancement of m CR * in CeSb.

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“…Later, it was pointed out that the pd mixing term plays important role [17][18][19] to explain the Fermi surfaces of CeSb in the ferromagnetic phase [20][21][22][23][24][25] and + + − phase. 25,26) In this paper, we employ the pf mixing model including the pd mixing effect, and examine the stability of the double layer structure in CeSb.…”

Section: §1 Introductionmentioning

confidence: 99%

“…The pd mixing term between X p p bands and Ce d bands is neglected in the energy calculation of the original pf mixing model, because the pd mixing effect dis-appears on the ∆ axis where the pf mixing becomes maximum. Later, it was pointed out that the pd mixing term plays important role [17][18][19] to explain the Fermi surfaces of CeSb in the ferromagnetic phase [20][21][22][23][24][25] and + + − phase. 25,26) In this paper, we employ the pf mixing model including the pd mixing effect, and examine the stability of the double layer structure in CeSb.…”

Section: §1 Introductionmentioning

confidence: 99%

Theory on the Stability of the Ferromagnetic Double Layer Structure and on the Peak Structure of the Magneto-Optical Spectra of CeSb

Ishiyama

Sakai

2003

J. Phys. Soc. Jpn.

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We propose the pf +pd mixing model for CeSb to explain the stability of the ferromagnetic double layer structure in the magnetic ordering. The pd mixing causes the saddle type singular points, neighboring the ∆ axis, for the bands which gain energy through the pf hybridization with the occupied f state. The peak of the density of states due to this combined effect of the pf mixing and the pd mixing enhances the stability of the double layer structure. The same combined effect also causes the saddle type singular points in the joint density of states of the optical transition. The peak structure of the magneto-optical spectra which has been observed in experiments is explained by the present model.KEYWORDS: CeSb, magnetic order, double layer structure, optical conductivity, pf mixing model §1. Introduction Cerium monopnictides (CeX p , X p =P, As, Sb, Bi) are semimetals with the NaCl type lattice. Their electronic bands have hole surfaces originated from atomic X p p states around Γ, and electron surfaces originated from Ce 5d states around three equivalent X.1) In the temperature (T) and the magnetic field (H) diagram, 2, 3) CeX p 's show various types of magnetic ordered states. They consist of the ferromagnetic layers which stack antiferromagnetically. Many types of stacking sequences appear in the phase diagram. Among CeX p 's, CeSb 3) and CeBi 4, 5) have the type-IA antiferromagnetic (+ + −−) phase with nearly full (J z ≃ ±5/2) magnetic moment as the ground state of weak H case. Here '+' denotes the ferromagnetic layer with the magnetic moment parallel to the field, and '−' denotes the layer anti-parallel to the field.The pair of ferromagnetic layers (++ or −−) is widely observed as a unit of the magnetic structure in CeX p 's. We call it as the 'double layer structure', hereafter.The phase diagram of CeSb has been qualitatively reproduced by the ANNNI model.6-8) However, it is not clear how the parameters of the phenomenological model are related to those of the microscopic model.The origin of the ferromagnetic layer with nearly full moment was explained by the pf mixing model 9-16) proposed by Kasuya et al. The model also succeeded in explaining the origin of the antiferromagnetic stacking of the ferromagnetic layers. However, the stability of the double layer structure with sufficient energy gain has not been obtained.The pd mixing term between X p p bands and Ce d bands is neglected in the energy calculation of the original pf mixing model, because the pd mixing effect dis- * Contact address: NTT Energy and Environment Systems Laboratories, Tokyo 180-8585 appears on the ∆ axis where the pf mixing becomes maximum. Later, it was pointed out that the pd mixing term plays important role [17][18][19] to explain the Fermi surfaces of CeSb in the ferromagnetic phase [20][21][22][23][24][25] and + + − phase. 25, 26)In this paper, we employ the pf mixing model including the pd mixing effect, and examine the stability of the double layer structure in CeSb. Hereafter, we call the model as the pf +pd mixing model. I...

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4f-band of Ce-compounds in photoexcitation and in low energy phenomena

Cited by 44 publications

References 20 publications

Elastic properties of the filled skutterudite compoundNdFe4P12

Elastic properties of the filled skutterudite compoundNdFe4P12

Cyclotron resonance in rare-earth monopnictides

Theory on the Stability of the Ferromagnetic Double Layer Structure and on the Peak Structure of the Magneto-Optical Spectra of CeSb

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