Quantum critical fluctuations in the heavy fermion compound Ce(Ni0.935Pd0.065)2Ge2

Wang, C. H.; Poudel, L.; Taylor, A. E.; Lawrence, J. M.; Christianson, A. D.; Chang, S.; Rodríguez-Rivera, J. A.; Lynn, J. W.; Podlesnyak, A.; Ehlers, Georg; Baumbach, R. E.; Bauer, E. D.; Gofryk, K.; Ronning, F.; McClellan, K. J.; Thompson, J. D.

doi:10.1088/0953-8984/27/1/015602

Cited by 5 publications

(4 citation statements)

References 21 publications

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“…However, C/T exhibits a logarithmic divergence at low temperatures with a large Sommerfeld coefficient γ ≃ 350 mJ/(mol K 2 ) [45,122]. The temperature dependence of the resistivity also shows non-Fermi liquid behavior, with a reported exponent n between 1.1 and 1.5 [46,122], where higher quality samples generally have a smaller n. It has been proposed that CeNi 2 Ge 2 is located near a three dimensional antiferromagnetic QCP [123], and the system can be driven to a QCP by doping the Ni site with about 6.5% Pd [124,125]. Evidence for a superconducting transition also appears below 0.2 K in resistivity measurements, although zero-resistance has not been reached, and NQR measurements were reported to show a slight decrease in 1/T 1 T , probably caused by this filamentary superconductivity [126].…”

Section: Superconductivity Near a Magnetic Instabilitymentioning

confidence: 99%

Multiple quantum phase transitions and superconductivity in Ce-based heavy fermions

et al. 2016

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Heavy fermions have served as prototype examples of strongly-correlated electron systems. The occurrence of unconventional superconductivity in close proximity to the electronic instabilities associated with various degrees of freedom points to an intricate relationship between superconductivity and other electronic states, which is unique but also shares some common features with high temperature superconductivity. The magnetic order in heavy fermion compounds can be continuously suppressed by tuning external parameters to a quantum critical point, and the role of quantum criticality in determining the properties of heavy fermion systems is an important unresolved issue. Here we review the recent progress of studies on Ce based heavy fermion superconductors, with an emphasis on the superconductivity emerging on the edge of magnetic and charge instabilities as well as the quantum phase transitions which occur by tuning different parameters, such as pressure, magnetic field and doping. We discuss systems where multiple quantum critical points occur and whether they can be classified in a unified manner, in particular in terms of the evolution of the Fermi surface topology.

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Section: Superconductivity Near a Magnetic Instabilitymentioning

confidence: 99%

Multiple quantum phase transitions and superconductivity in Ce-based heavy fermions

et al. 2016

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“…The obtained small value of δ suggests the presence of the existence of unusual fluctuation. These unusual fluctuations indicate a deviation from the typical 3d critical fluctuation and probably arise due to disorder effect because of Y-substitution at the Ce-site [29]. Hence it can be said that anomalous quantum criticality is observed in Y-0.4 compound.…”

Section: Resultsmentioning

confidence: 92%

Observation of field induced anomalous quantum criticality in Ce0.6Y0.4NiGe2 compound

Singh

Mukherjee

2019

Physics Letters A

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We report the results of our investigation of magnetization and heat capacity on a series of compounds Ce 1-x Y x NiGe 2 (x = 0.1, 0.2 and 0.4) under the influence of external magnetic field.Our studies of the thermodynamic quantity -dM/dT on these compounds indicate that magnetic frustration persists in Ce 0.9 Y 0.1 NiGe 2 , as also reported for the parent compound CeNiGe 2 . The weak signature of this frustration is also noted in Ce 0.8 Y 0.2 NiGe 2 , whereas, it is suppressed in Ce 0.6 Y 0.4 NiGe 2 . Heat capacity studies on Ce 0.9 Y 0.1 NiGe 2 and Ce 0.8 Y 0.2 NiGe 2 indicate the presence of a new magnetic anomaly at high field which indicates that quantum criticality is absent in these compounds. However, for Ce 0.6 Y 0.4 NiGe 2 such an anomaly is not noted. For this later compound, the magnetic field (H) and temperature (T) dependence of heat capacity and magnetization obey H/T scaling above critical fields. However, the obtained scaling critical parameter (δ) is 1.6, which is away from mean field value of 3. This deviation suggests the presence of unusual fluctuations and anomalous quantum criticality in these compounds. This unusual fluctuation may arise from disorderness induced by Y-substitution.

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“…In addition, it has been established from earlier studies on other QCP systems that the correlation lengths remain finite while C/T shows a strong divergence. [45][46][47] Such non diverging correlation lengths has been attributed to the presence of intrinsic disorder or the phase transition becoming weakly first order [45][46][47] and similar explanations may be relevant for CeCu 6−x Ag x .…”

Section: Discussionmentioning

confidence: 89%

Multicomponent fluctuation spectrum at the quantum critical point in CeCu6−xAgx

Poudel

Lawrence

et al. 2019

npj Quantum Mater.

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Quantum critical points (QCPs) are widely accepted as a source of a diverse set of collective quantum phases of matter. The basic nature of a QCP is manifested in the critical fluctuation spectrum which in turn is determined by the adjacent phases and associated order parameters. Here we show that the critical fluctuation spectrum of CeCu 5.8 Ag 0.2 can not be explained by fluctuations associated with a single wave vector. Interestingly, when the critical fluctuations at wave vectors corresponding to the incommensurate antiferromagnetic order adjacent to the QCP are separated they are found to be three dimensional and to obey the scaling behavior expected for long wavelength fluctuations near an itinerant antiferromagnetic QCP. Without this separation, E/ T scaling with a fractional exponent is observed. Together these results demonstrate that a multicomponent fluctuation spectrum is a previously unexplored route to obtaining E/T scaling at a QCP.

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Quantum critical fluctuations in the heavy fermion compound Ce(Ni_0.935Pd_0.065)₂Ge₂

Cited by 5 publications

References 21 publications

Multiple quantum phase transitions and superconductivity in Ce-based heavy fermions

Multiple quantum phase transitions and superconductivity in Ce-based heavy fermions

Observation of field induced anomalous quantum criticality in Ce0.6Y0.4NiGe2 compound

Multicomponent fluctuation spectrum at the quantum critical point in CeCu6−xAgx

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