Formation of a Hybridization Gap in a Cage-Like Compound CeFe<sub>2</sub>Al<sub>10</sub>

Muro, Yuji; Motoya, Kiyoichiro; Saiga, Yasuhiro; Takabatake, Toshiro

doi:10.1143/jpsj.78.083707

Cited by 121 publications

(123 citation statements)

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“…Since we considered only theĈ (2) ±2 term, and have not tried to fit the data by including more terms in H CEF , there still remains a room for further improvement in the fitting, such as the absolute values of χ(T ) at low temperatures. However, in the present two-sublattice Hamiltonian, it seems difficult to reproduce the increase of χ a (T ) and χ c (T ) with decreasing T even below T N as shown in Fig.…”

Section: Crystal Field Analysis Of Magnetic Susceptibilitymentioning

confidence: 99%

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Incommensurate-commensurate magnetic phase transition inSmRu2Al10

et al. 2015

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Magnetic properties of single crystalline SmRu2Al10 have been investigated by electrical resistivity, magnetic susceptibility, and specific heat. We have confirmed the successive magnetic phase transitions at TN = 12.3 K and TM = 5.6 K. Resonant x-ray diffraction has also been performed to study the magnetic structures. Below TN, the Sm 3+ moments order in an incommensurate structure with q1 = (0, 0.759, 0). The magnetic moments are oriented along the orthorhombic b axis, which coincides with the magnetization easy axis in the paramagnetic phase. A very weak third harmonic peak is also observed at q3 = (0, 0.278, 0). The transition at TM is a lock-in transition to the commensurate structure described by q1 = (0, 0.75, 0). A well developed third harmonic peak is observed at q3 = (0, 0.25, 0). From the discussion of the magnetic structure, we propose that the long-range RKKY interaction plays an important role, in addition to the strong nearest neighbor antiferromagnetic interaction.

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Section: Crystal Field Analysis Of Magnetic Susceptibilitymentioning

confidence: 99%

“…[2][3][4][5] The most prominent feature is its high transition temperature, T 0 =27.3 K for CeRu 2 Al 10 and 28.7 K for CeOs 2 Al 10 , respectively, which are much higher than T N =16 K of GdRu 2 Al 10 . 6 There are several noteworthy properties associated with this phase transition.…”

Section: Introductionmentioning

confidence: 99%

Incommensurate-commensurate magnetic phase transition inSmRu2Al10

et al. 2015

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“…3), have generated considerable interest in both theoretical and experimental condensed matter physics [28,[29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48]. This interest arose due to the various interesting ground states observed in this family of Ce-compounds as well as their caged type crystal structure that is important for the enhanced thermoelectric properties.…”

Section: Kondo Insulating Behavior Of Cet 2 Al 10mentioning

confidence: 99%

“…The broad maximum in the susceptibility indicates the opening of a spin or hybridization gap (Fig.4). On the other hand, the susceptibility of CeFe 2 Al 10 along the a-axis exhibits a broad maximum near 75 K without any sign of magnetic ordering [28,33], which indicates that the Ce ions are in the valence fluctuating or mixed valence state, as confirmed by L 3 -edge x-ray absorption spectroscopy [46]. Further the strong anisotropic behavior in the paramagnetic state of all three compounds reveals the presence of strong hybridization between 4f-and conduction electrons.…”

Section: Kondo Insulating Behavior Of Cet 2 Al 10mentioning

confidence: 99%

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Adroja¹,

Muro²,

Takabatake³

et al. 2016

SSP

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Abstract. The recent discovery of topological Kondo insulating behaviour in strongly correlated electron systems has generated considerable interest in Kondo insulators both experimentally and theoretically. The Kondo semiconductors CeT 2 Al 10 (T=Fe, Ru and Os) possessing a c-f hybridization gap have received considerable attention recently because of the unexpected high magnetic ordering temperature of CeRu 2 Al 10 (T N =27 K) and CeOs 2 Al 10 (T N =28.5 K) and the Kondo insulating behaviour observed in the valence fluctuating compound CeFe 2 Al 10 with a paramagnetic ground state down to 50 mK. We are investigating this family of compounds, both in polycrystalline and single crystal form, using inelastic neutron scattering to understand the role of anisotropic c-f hybridization on the spin gap formation as well as on their magnetic properties. We have observed a clear sign of a spin gap in all three compounds from our polycrystalline study as well as the existence of a spin gap above the magnetic ordering temperature in T=Ru and Os. Our inelastic neutron scattering studies on single crystals of CeRu 2 Al 10 and CeOs 2 Al 10 revealed dispersive gapped spin wave excitations below T N . Analysis of the spin wave spectrum reveals the presence of strong anisotropic exchange, along the c-axis (or z-axis) stronger than in the ab-plane. These anisotropic exchange interactions force the magnetic moment to align along the c-axis, competing with the single ion crystal field anisotropy, which prefers moments along the a-axis. In the paramagnetic state (below 50 K) of the Kondo insulator CeFe 2 Al 10 , we have also observed dispersive gapped magnetic excitations which transform into quasi-elastic scattering on heating to 100 K. We will discuss the origin of the anisotropic hybridization gap in CeFe 2 Al 10 based on theoretical models of heavy-fermion semiconductors.

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“…The family of the compounds has attracted interest because of the discovery of anomalous ordered states in Ce compounds [1][2][3][4]. Electronic transport property of CeRu 2 Al 10 shows activation behavior with small gap above the transition temperature T * = 27 K. To explain the activation behavior, a spin-Peierls transition of the zigzag chain of Ce along the c axis has been proposed [5].…”

Section: Introductionmentioning

confidence: 99%

Measurement of Crystal Field Excitations in NdT₂Al₁₀ (T = Ru and Os) by Raman Scattering

Nagano¹,

Hasegawa²,

Ogita³

et al. 2014

Proceedings of the International Conference on Strongly Correlated Electron Systems (SCES2013)

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Raman scattering spectra of NdRu 2 Al 10 and NdOs 2 Al 10 single crystals have been measured from 4 K to 300 K. Crystal field excitations have been observed at 4 K in both compounds. Crystal field states of Nd 3+ split into five doubly-degenerated states in this crystal structure. All their energy levels have been determined. However, we have found that the second excitation takes different energy for different irreducible representations. This means that the excited states split in these compounds, while they are usually degenerated under static crystal field. One possibility of the splitting is dynamical effect, e.g. interaction with conduction electrons, or interaction with a phonon.

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Formation of a Hybridization Gap in a Cage-Like Compound CeFe₂Al₁₀

Cited by 121 publications

References 18 publications

Incommensurate-commensurate magnetic phase transition inSmRu2Al10

Incommensurate-commensurate magnetic phase transition inSmRu2Al10

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Measurement of Crystal Field Excitations in NdT₂Al₁₀ (T = Ru and Os) by Raman Scattering

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Formation of a Hybridization Gap in a Cage-Like Compound CeFe2Al10

Cited by 121 publications

References 18 publications

Incommensurate-commensurate magnetic phase transition inSmRu2Al10

Incommensurate-commensurate magnetic phase transition inSmRu2Al10

Untitled

Measurement of Crystal Field Excitations in NdT2Al10 (T = Ru and Os) by Raman Scattering

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Formation of a Hybridization Gap in a Cage-Like Compound CeFe₂Al₁₀

Measurement of Crystal Field Excitations in NdT₂Al₁₀ (T = Ru and Os) by Raman Scattering