Unusual phase boundary of the magnetic-field-tuned valence transition in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>CeOs</mml:mi><mml:mn>4</mml:mn></mml:msub><mml:msub><mml:mi>Sb</mml:mi><mml:mn>12</mml:mn></mml:msub></mml:mrow></mml:math>

Götze, K.; Pearce, Matthew; Goddard, Paul; Jaime, M.; Maple, M. B.; Sasmal, Kalyan; Yanagisawa, Tatsuya; McCollam, A.; Khouri, T.; Ho, Pei-Chun; Singleton, John

doi:10.1103/physrevb.101.075102

Cited by 10 publications

(40 citation statements)

References 43 publications

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“…2c. The θ −dependence of F KM (µ 0 H I−M ) thus deduced tracks the behaviour of the dHvA frequencies measured in the KI state, albeit with an offset ≈ 100 T. This offset may be due to a discontinuous change in F at the phase boundary; however, it could also result from the potential uncertainty in determining the H-position of any phase transition associated with a valence change [25]. Substituting values of µ 0 H I−M decreased by ≈ 0.8 T into Eq.…”

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confidence: 58%

Unusual high-field metal in a Kondo insulator

Xiang,

Chen,

Chen

et al. 2021

Preprint

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Within condensed-matter systems, strong electronic interactions often lead to exotic quantum phases. A recent manifestation of this is the unexpected observation of magnetic quantum oscillations [1][2][3][4] and metallic thermal transport [5,6], both properties of systems with Fermi surfaces of itinerant quasiparticles, in the Kondo insulators SmB 6 and YbB 12 . To understand these phenomena, it is informative to study their evolution as the energy gap of the Kondo-Insulator state is closed by a large magnetic field. We show here that both the quantumoscillation frequency and the cyclotron mass display a strong field dependence in the resulting high-field metallic state in YbB 12 . By tracking the Fermi-surface area, we conclude that the same quasiparticle band gives rise to the quantum oscillations in both insulating and metallic states. These data are understood most simply using a twofluid picture where unusual quasiparticles, contributing little or nothing to charge transport, coexist with conventional fermions. In the metallic state this leads to a heavyfermion bad metal with negligible magnetoresistance, relatively high resistivity and a very large Kadowaki-Woods ratio, underlining the exotic nature of the fermion ensemble inhabiting YbB 12 .In Kondo insulators (KIs), an energy gap is opened up by strong coupling between a lattice of localized moments and the extended electronic states. The resulting Kondo gap E g is usually narrow (typically E g ≃ 5 − 20 meV), yet the rôle it plays in charge transport is more complicated than that of the bandgap in conventional semiconductors. A low-temperature (T ) saturation of the resistivity ρ has long been known in two prototypical KIs, SmB 6 and YbB 12 [7,8]; both are mixedvalence compounds with strong f − d hybridization that defines the band structure close to the Fermi energy. While the saturation might suggest additional metallic conduction channels, the high resistivity value within the weakly T -dependent "plateau" implies an unconventional nature for such channels [4,7].Recently, magnetic quantum oscillations, suggestive of a Fermi surface (FS), and thus totally unexpected in an insulator, have been detected in both SmB 6 and YbB 12 [1][2][3][4].

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confidence: 58%

Unusual high-field metal in a Kondo insulator

Xiang,

Chen,

Chen

et al. 2021

Preprint

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“…[16] and [17] by dilatometry, magnetization and neutron scattering suggests that there may in fact be three separate phases (see inset of Fig. 1): a magnetically ordered phase below 1 K and 1 T in the H-T phase diagram that we call S afm , a sub-phase of S afm here named S A which exists below T =900 mK, and a high-field ordered phase S B which is possibly an antiferro- Ambient pressure phase diagram of CeOs 4 Sb 12 as established in [15]. Different colours symbolize results from different crystals.…”

Section: Introductionmentioning

confidence: 77%

“…quadrupolar or charge-density wave phase [16]. Quantum criticality close to the suppression of the S B -phase towards zero temperature at approximately 20 T is associated with additional energy scales that cause the deviation of the phase boundary from the expected elliptical behaviour and also leads to a field-dependent increase of the effective quasiparticle masses as observed in quantum-oscillation experiments [15]. The Fermi surface (FS) of the H-phase consists of a single, central spherical FS sheet theoretically predicted in Refs.…”

Section: Introductionmentioning

confidence: 84%

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Pressure-induced shift of effective Ce valence, Fermi energy and phase boundaries in CeOs$_4$Sb$_{12}$

Götze,

Pearce,

Coak

et al. 2021

Preprint

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CeOs 4 Sb 12 , a member of the skutterudite family, has an unusual semimetallic lowtemperature L-phase that inhabits a wedge-like area of the field H -temperature T phase diagram. We have conducted measurements of electrical transport and megahertz conductivity on CeOs 4 Sb 12 single crystals under pressures of up to 3 GPa and in high magnetic fields of up to 41 T to investigate the influence of pressure on the different H-T phase boundaries. While the high-temperature valence transition between the metallic H-phase and the L-phase is shifted to higher T by pressures of the order of 1 GPa, we observed only a marginal suppression of the S-phase that is found below 1 K for pressures of up to 1.91 GPa. High-field quantum oscillations have been observed for pressures up to 3.0 GPa and the Fermi surface of the highfield side of the H-phase is found to show a surprising decrease in size with increasing pressure, implying a change in electronic structure rather than a mere contraction of lattice parameters. We evaluate the field-dependence of the effective masses for different pressures and also reflect on the sample dependence of some of the properties of CeOs 4 Sb 12 which appears to be limited to the low-field region.

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“…Pressure suppresses magnetism in favor of delocalized 4 f states by increasing the hybridization 11 , 28 , 37 , 38 . Magnetic field, on the other hand, favors localized moments aligned along the field in a field-polarized paramagnetic state, which clearly is the fate of any Ce-compound in the infinite field limit once the Zeeman energy surpasses any other energy scale 39 – 41 . While both states do not show magnetic order, they strongly differ in the degree of localization, and hence it is clear that the joint effect of field and pressure cannot be a swift suppression of AFM.…”

Section: Discussionmentioning

confidence: 99%

Non-monotonic pressure dependence of high-field nematicity and magnetism in CeRhIn5

et al. 2020

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CeRhIn 5 provides a textbook example of quantum criticality in a heavy fermion system: Pressure suppresses local-moment antiferromagnetic (AFM) order and induces superconductivity in a dome around the associated quantum critical point (QCP) near p c ≈ 23 kbar. Strong magnetic fields also suppress the AFM order at a field-induced QCP at B c ≈ 50 T. In its vicinity, a nematic phase at B * ≈ 28 T characterized by a large in-plane resistivity anisotropy emerges. Here, we directly investigate the interrelation between these phenomena via magnetoresistivity measurements under high pressure. As pressure increases, the nematic transition shifts to higher fields, until it vanishes just below p c. While pressure suppresses magnetic order in zero field as p c is approached, we find magnetism to strengthen under strong magnetic fields due to suppression of the Kondo effect. We reveal a strongly nonmean-field-like phase diagram, much richer than the common local-moment description of CeRhIn 5 would suggest.

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Unusual phase boundary of the magnetic-field-tuned valence transition inCeOs4Sb12

Cited by 10 publications

References 43 publications

Unusual high-field metal in a Kondo insulator

Unusual high-field metal in a Kondo insulator

Pressure-induced shift of effective Ce valence, Fermi energy and phase boundaries in CeOs$_4$Sb$_{12}$

Non-monotonic pressure dependence of high-field nematicity and magnetism in CeRhIn5

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