Resonant Mode in Rare-earth based Strongly Correlated Semiconductors

Nemkovski, K. S.; Alekseev, P. A.; Mignot, J.-M.; Ivanov, Alexander S.

doi:10.1016/j.phpro.2013.03.170

Cited by 11 publications

(17 citation statements)

References 31 publications

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“…The first one is that, in YbB 12 , the narrow peak associated with the RM at 15 meV is already strongly suppressed when temperature is raised to no more than 30 K, i.e., just before the spin gap begins to fill. This is in good agreement with our recent single-crystal data [8], which demonstrated the complete suppression of the RM at q = (1/2, 1/2, 1/2) above 40 K, without a significant shift in its energy [Figs. 7(a) and 7(b)].…”

Section: B Spin-gap Energy Range (In4c)supporting

confidence: 93%

“…7(a) and 7(b)]. It also confirms a previous study of the temperature evolution of the magnetic spectral response in YbB 12 powder [8,15], which concluded to a filling of the gap by a quasielastic signal [Fig. 7(c)].…”

Section: B Spin-gap Energy Range (In4c)supporting

confidence: 88%

“…It transforms to a single-site spin-fluctuation regime above 60 K, with a characteristic spin-fluctuation temperature T sf on the order of 100 K. The low-temperature regime is characterized by the existence of both a charge [5] and a spin [6] gap. In addition, a resonance mode (RM) of spin-exciton type with sizable dispersion was shown to exist at about 15 meV, below the spin-gap edge, for temperatures lower than about 40 K [7,8]. A cooperative state thus appears to form in this temperature range as a result of Kondo-like compensation effects in the strongly correlated electron system.…”

Section: Introductionmentioning

confidence: 96%

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Possible undercompensation effect in the Kondo insulator (Yb,Tm)B12

et al. 2014

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The effects of Tm substitution on the dynamical magnetic response of Yb 1−x Tm x B 12 (x = 0, 0.08, 0.15, and 0.75) and Lu 0.92 Tm 0.08 B 12 compounds have been studied using time-of-flight inelastic neutron scattering. Major changes were observed in the spectral structure and temperature evolution of the Yb contribution to the inelastic response for a rather low content of magnetic Tm ions. A sizable influence of the RB 12 host (YbB 12 , as compared to LuB 12 or pure TmB 12) on the crystal-field splitting of the Tm 3+ ion is also reported. The results point to a specific effect of impurities carrying a magnetic moment (Tm, as compared to Lu or Zr) in a Kondo insulator, which is thought to reflect the "undercompensation" of Yb magnetic moments, originally Kondo screened in pure YbB 12. A parallel is made with the strong effect of Tm substitution on the temperature dependence of the Seebeck coefficient in Yb 1−x Tm x B 12 , which was reported previously.

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Section: B Spin-gap Energy Range (In4c)supporting

confidence: 93%

Section: B Spin-gap Energy Range (In4c)supporting

confidence: 88%

Section: Introductionmentioning

confidence: 96%

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Possible undercompensation effect in the Kondo insulator (Yb,Tm)B12

et al. 2014

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“…The mode exhibits a positive dispersion from a zone-boundary q vector, with intensity decreasing rapidly as the energy comes closer to the continuum. With increasing temperature, the peak is rapidly suppressed but does not appear to move significantly to lower energies, as was already noted for YbB 12 [16]. In Riseborough's model [3], the exciton peak requires both a sizable exchange interaction J (q AF ) and a large value of the magnetic susceptibility χ 0 (q AF ,E).…”

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confidence: 59%

“…This behavior is at variance with that reported for CeRu 2 Al 10 [10,11,15], in which the energy of the magnonlike excitation at the spin-gap edge decreases as T increases toward the Néel temperature T 0 in the AFM phase. On the other hand, it is reminiscent of the temperature suppression of the magnetic exciton mode in YbB 12 [2,16].…”

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confidence: 99%

Dispersive magnetic-resonance mode in the Kondo semiconductor CeFe2Al10

et al. 2014

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The CeT 2 Al 10 family of orthorhombic compounds exhibits a very peculiar evolution from a Kondo insulator (T : Fe) to an unconventional long-range magnetic order (T : Ru, Os). Inelastic neutron-scattering experiments performed on single-crystal CeFe 2 Al 10 reveal that this material develops a spin gap in its magnetic spectral response below ∼50 K, with a magnetic excitation dispersing from E = 10.2 ± 0.5 meV at the Y zone-boundary point [q = (0,1,0)] to ≈12 meV at the top of the branch. The excitation shows a pronounced polarization of the magnetic fluctuations along a, the easy anisotropy axis. Its behavior is contrasted with that of the (magnonlike) modes previously reported for CeRu 2 Al 10 , which have transverse character and exist only in the antiferromagnetic state. The present observation is ascribed to a "magnetic exciton" mechanism invoked to explain a similar magnetic response previously discovered in YbB 12 .Kondo insulators (KIs) form a unique class of materials, in which semiconducting properties develop on cooling as a result of the opening of a narrow gap in the electronic density of states at the Fermi energy [1]. One central issue to understanding the peculiar properties of these materials is the interplay between the nonmagnetic singlet ground state prevailing in most KI materials at low temperature, and the tendency to develop short-range, dynamical, antiferromagnetic (AF) correlations, revealed by inelastic neutron scattering (INS) measurements. In the archetype compound YbB 12 , we have shown previously that the low-energy magnetic response in the KI state is dominated by a sharp, resolution-limited peak, located just below the edge of a spin gap, which disappears rapidly upon heating as the system enters the incoherent spin fluctuation regime [2]. This excitation was interpreted by Riseborough [3] as an exciton peak (a resonance mode in the spin response function) reflecting residual AF interactions between the renormalized 4f quasiparticles. This model is reminiscent of that proposed for the well-known "resonance mode" (RM) in high-T c superconductors [4]. A similar situation possibly occurs in SmB 6 as well [5]. On the other hand, evidence is still lacking for the existence of a RM-type excitation in the case of the Ce-based KIs, primarily because detailed studies of the q dependence of the magnetic response on single crystals are scarce [6].In this Rapid Communication, we present new INS results showing that CeFe 2 Al 10 is likely the first example of a Ce system with a RM excitation in the KI state. This compound belongs to the "1-2-10" series (RT 2 Al 10 with R a lanthanide element and T a transition-metal element such as Fe, Ru, or Os). Unlike its Ru and Os counterparts, which have been * jean-michel.mignot@cea.fr † Present address: Quantum Condensed Matter Division, ORNL, Oak Ridge, Tennessee 37831, USA. extensively investigated for their unconventional combination of KI behavior and long-range magnetic order [7], CeFe 2 Al 10 is a classical KI, in which no magnetic order was obser...

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Spectral characteristics of the antiferromagnetic spin-1/2 Heisenberg model on the square lattice in a magnetic field

Savchenkov

Барабанов

2021

Journal of Magnetism and Magnetic Materials

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Resonant Mode in Rare-earth based Strongly Correlated Semiconductors

Cited by 11 publications

References 31 publications

Possible undercompensation effect in the Kondo insulator (Yb,Tm)B12

Possible undercompensation effect in the Kondo insulator (Yb,Tm)B12

Dispersive magnetic-resonance mode in the Kondo semiconductor CeFe2Al10

Spectral characteristics of the antiferromagnetic spin-1/2 Heisenberg model on the square lattice in a magnetic field

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