The magnetic phase transitions in Ce-monopnictides, strong p-f mixing effect

Kasuya, T.; Kwon, Yong Seung; Suzuki, Takashi; Nakanishi, Kazuo; Ishiyama, Fumihiko; Takegahara, Katsuhiko

doi:10.1016/s0304-8853(10)80140-4

Cited by 54 publications

(16 citation statements)

References 15 publications

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“…It is well known that in zero field CeSb exhibits seven magnetic transitions between 17 and 8 K. 11,12,14 However, ␣ 4 f (T) shows only two well-resolved peaks. A very similar behavior has been observed in the zero-field heat capacity (C v )o fa polycrystalline CeSb sample, 1,28 while seven transitions are observed in the heat capacity of a single crystal of CeSb. 14 The ratio of the heights of the two peaks in the thermal expansion and heat capacity of the polycrystalline samples agrees well.…”

Section: Thermal Expansionsupporting

confidence: 72%

“…Further, the second peak also broadens in the 8 T field and moves to a lower temperature ͑11 K͒. It would be interesting to compare the thermal expansion coefficient results with the heat capacity measured in an applied field of 5 and 10 T. 1,28 In the 5 T field the sharp peak in the C v (T) has been observed at 22 K due to the para to ferro-para ͑FP1, with k ϭ6/11,↑↑᭺᭺↑↑᭺᭺↑᭺) phase transition. For the 10 T field C v (T) exhibits a broad peak ͑second-order type͒ near 25 K, which is most likely due to FP2 (kϭ1/2, ↑↑᭺᭺͒ to FPЈ (kϭ1/2, ↑↑↑᭺͒ phase transition, and a sharp peak ͑first-order type͒ near 19 K, which is due to FPЈ (kϭ1/2, ↑↑↑᭺͒ to the ferromagnetic phase (kϭ0).…”

Section: Thermal Expansionmentioning

confidence: 99%

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Neutron scattering and thermal studies of the Ni-incorporatedCeSbNixsystem

et al. 2000

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Neutron scattering and thermal studies of the Ni-incorporated CeSbNix system Adroja, D. T.; Armitage, J. G. M.; Riedi, P. C.; Jung, M. H.; Tun, Z.; Takabatake, T. Neutron scattering, thermal expansion, and magnetostriction measurements have been carried out on the cubic compounds CeSbNi x (xϭ0 -0.4). Inelastic neutron scattering studies show a well-defined crystal field ͑CF͒ excitation at 4.06 ͑Ϯ0.04͒ meV and 5.02͑Ϯ0.05͒ meV in xϭ0.08 and 0.15, respectively. The crystal field splitting increases with x compared with the parent compound CeSb ͑3.19 meV͒ in spite of the lattice parameter increasing with Ni incorporation. The implication is that the increase in the CF splitting in xϭ0.08 and 0.15 is due to a collapse of the p-f mixing between the Sb 5p holes and the localized Ce 4 f electrons. The analysis of inelastic spectra of xϭ0.15 shows that the ground state is a doublet (⌫ 7 ), which explains the temperature-dependent behavior of the magnetic susceptibility. Thermal expansion shows a dramatic change in behavior with Ni composition. The thermal expansion coefficient exhibits a first-order transition at 15.4 K in CeSb, which disappears for Ni composition as low as xϭ0.035, as well as in an applied field of 8 T. A large magnetostriction has been observed in CeSb in the magnetic-ordered state as well as in the paramagnetic state.The absolute values of the magnetostriction are reduced considerably in the Ni-incorporated alloys. The volume magnetostriction of xϭ0.15 alloy exhibits a scaling behavior in the paramagnetic state from which we have estimated the product of the magnetovolume coupling constant and the isothermal compressibility.

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Section: Thermal Expansionsupporting

confidence: 72%

Section: Thermal Expansionmentioning

confidence: 99%

Neutron scattering and thermal studies of the Ni-incorporatedCeSbNixsystem

et al. 2000

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“…Although not completely understood, it is admitted that the original properties of this compound are related to p-f mixing that leads to a Kondo effect in presence of frustrated exchange interactions. 5,6 More recently mixed phases with normal rare earths have been suggested to exist. However one has to distinguish between systems in which the mixed phase with ''paramagnetic'' planes is induced by temperature, such as those proposed in PrCo 2 Si 2 , 7 and those in which the mixed state, with atoms in a ''zero moment'' state are, on the contrary, expected only at low temperature such as could be the case in TbRu 2 Si 2 .…”

Section: Introductionmentioning

confidence: 99%

Evidence of mixed magnetic phases inTbRu2Ge2

et al. 1998

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In compounds with normal rare earths at the same crystallographic site, mixed magnetic phases with two distinct rare-earth magnetic states, namely, a zero moment one and another with a high moment, can be stabilized at low temperature not only in zero applied field but also in different field-induced magnetic phases of a metamagnetic process. These characteristics are observed in tetragonal TbRu 2 Ge 2 from neutron diffraction and magnetization measurements on a single crystal. It is shown that such magnetic structures may originate from a moment instability due to the crystal field in the presence of frustrated exchange interactions. Numerical simulations using the periodic-field model allowed us to satisfactorily account for the observed properties and emphasize the crucial role played by the crystal field. ͓S0163-1829͑98͒00209-4͔

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“…[6][7][8] However, it is not clear how the parameters of the phenomenological model are related to those of the microscopic model.…”

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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The magnetic phase transitions in Ce-monopnictides, strong p-f mixing effect

Cited by 54 publications

References 15 publications

Neutron scattering and thermal studies of the Ni-incorporatedCeSbNixsystem

Neutron scattering and thermal studies of the Ni-incorporatedCeSbNixsystem

Evidence of mixed magnetic phases inTbRu2Ge2

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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