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Montfrooij, Wouter; Aronson, M. C.; Rainford, B.D.; Mydosh, J. A.; Murani, A.P.; Haen, P.; Fukuhara, Tadashi

doi:10.1103/physrevlett.91.087202

Cited by 38 publications

(38 citation statements)

References 20 publications

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“…3͑b͒ we show the TRIAX data at q = 1.4 Å −1 for 5 Ͻ T Ͻ 70 K. The energy and temperature dependence of the scattering follows curves that are functions of E / T only ͑straight lines in the figure͒ and therefore, the scattering associated with the superspins could easily be interpreted as exhibiting E / T scaling such as observed in CeCu 5.9 Au 0.1 , 2 UCu 5−x Pd x , 10 and Ce͑Ru 1−x Fe x ͒ 2 Ge 2 . 3 Thus, the dynamics of this classical system of clusters are annoyingly similar to what one observes in doped quantum critical systems. This similarity is particularly strong in the case of heavily doped UCu 5−x Pd x ͑x =1,1.5͒ 10 where the static structure factor closely follows that of our system, 5 and where the dynamics do not show any significant q-dependence when plotted as S͑q , E , T͒ / S͑q , T͒ as we did in Fig.…”

Section: E322-2supporting

confidence: 64%

“…Given the high likelihood 3 that quantum critical systems prepared by means of substantial chemical doping 5,10 will fragment into a collection of magnetic clusters upon cooling, it appears that in describing the physics at a QCP one should take into account the inherent change in sample morphology when a system is cooled to 0 K. …”

Section: E322-2mentioning

confidence: 99%

“…CeFe 2 Ge 2 is a heavy fermion system 4 which upon increased doping x of Ru on the Fe sites orders magnetically at 0 K once 1:4 Fe ions have been substituted. 3 Since this doping is being done on sites that are not nearest neighbors to the moment carrying Ce sites, and since this substitution is isovalent, this system should have yielded unambiguous results.…”

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confidence: 99%

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The search for quantum critical scaling in a classical system

Lamsal

Gaddy

Petrovic

et al. 2009

Journal of Applied Physics

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Order-disorder phase transitions in magnetic metals that occur at zero temperature have been studied in great detail. Theorists have advanced scenarios for these quantum critical systems in which the unusual response can be seen to evolve from a competition between ordering and disordering tendencies, driven by quantum fluctuations. Unfortunately, there is a potential disconnect between the real systems that are being studied experimentally, and the idealized systems that theoretical scenarios are based upon. Here we discuss how disorder introduces a change in morphology from a three-dimensional system to a collection of magnetic clusters, and we present neutron scattering data on a classical system, Li͓Mn Quantum fluctuations can be strong enough to prevent a system from ordering, even at 0 K. In metals that possess atomic magnetic moments, one can tweak the strength of the magnetic interactions compared to the disordering quantum fluctuations in such a way that the system orders exactly at 0 K. Such a system is said to be at the quantum critical point ͑QCP͒. The interest in such systems is easy to understand. One can expect a new type of ordering behavior because the spatial and temporal dimensions are no longer independent at 0 K.1 Also, one can expect new physics to emerge. After all, when a system is on the verge of ordering at 0 K, the degrees of freedom that prevent the system from ordering also provide a channel for the system to adopt a new, lower energy ground state. An example is the observed superconducting state 1 that forms close to the QCP with quasiparticles consisting of some admixture of magnetic moments and conduction electrons.The question that has attracted most attention is "what exactly happens at the QCP?" On the one hand, 2 it could be that all moments will become fully shielded at some finite temperature, with the residual interaction between the resulting heavy quasiparticles driving the system toward ordering ͓Fig. 1͑a͔͒. On the other hand, 2 the QCP could be the point in the phase diagram where vestiges of moments can survive all the way down to 0 K upon cooling without being completely screened though the Kondo effect, resulting in long-range order ͓Fig. 1͑b͔͒. Unfortunately, the experimental situation is much murkier than a simple choice between these two possible answers.To drive a system to a QCP, one tweaks the interaction between moments by changing the degree of overlap between the local atomic orbitals and the extended conduction electron bands. Ideally, one simply applies hydrostatic pressure to a system without any intrinsic disorder, and all magnetic moments will undergo the same temperature evolution. This is the situation that most theoretical efforts have focused on ͓Ref. 1͔. In some experiments however, one cannot attain the high pressures required and one results to applying chemical pressure. Here, some elements are substituted with different sized ones so as to achieve lattice expansion/ contraction at the cost of introducing some disorder. However, it was generally...

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Section: E322-2supporting

confidence: 64%

Section: E322-2mentioning

confidence: 99%

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The search for quantum critical scaling in a classical system

Lamsal

Gaddy

Petrovic

et al. 2009

Journal of Applied Physics

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“…This non-Fermi-liquid ͑nFl͒ state of matter 8,9 can also be accompanied by dynamic scaling laws. 13 For instance, when the system is probed on a microscopic scale such as in neutron-scattering experiments, its response to a perturbation from equilibrium by an amount of energy E while at a temperature T, depends only on the ratio E / T. [12][13][14][15][16] The emergence of E / T scaling was particularly surprising since it occurred not only in systems that were ͑most likely͒ just below 17 the upper critical dimension 8 ͓CeCu 5.9 Au 0.1 ͑Ref. 12͔͒ but also in systems that were manifestly above the upper critical dimension ͓UCu 5−x Pd x for x = 1.0, 1.5 ͑Refs.…”

Section: Introductionmentioning

confidence: 99%

Magnetic excitations in the spinel compoundLix[Mn1.96Li0.04]
Heitmann
¹
,
Schmets
²
,
Gaddy
³

et al. 2010
Phys. Rev. B
9
0
4
0
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We present neutron-scattering results on the magnetic excitations in the spinel compounds Li x ͓Mn 1.96 Li 0.04 ͔O 4 ͑x = 0.2, 0.6, 0.8, 1.0͒. We show that the dominant excitations below T ϳ 70 K are determined by Mn ions located in clusters, and that these excitations mimic the dynamic scaling found in quantum critical systems that also harbor magnetic clusters, such as CeRu 0.5 Fe 1.5 Ge 2 . We argue that our results for this classical spinel compound suggest that the unusual response at low temperatures as observed in quantum critical systems that have been driven to criticality through substantial chemical doping is ͑at least͒ partially the result of the fragmentation of the magnetic lattice into smaller units.

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“…29) In this case, the magnetic moments are unquenched around the QCP, and the critical behavior is modulated by local and extended bidimensional (2D) magnetic fluctuations. 31) If the USC state sets in, the pairing mechanism is mediated by antiferromagnetic spin fluctuations. 9) In the case of our CePt and YbFe 2 Ge 2 compounds, however, the resistivity curves close to P c do not show evidence of superconducting state down to 50 mK.…”

Section: Residual Resistivity In Hfmentioning

confidence: 99%

Quantum Criticality of CePt and YbFe₂Ge₂Heavy Fermions under Pressure

Fontes

Baggio-Saitovitch

et al. 2007

J. Phys. Soc. Jpn.

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This work reports the study of the quantum criticality of the ferromagnetic (FM) CePt Kondo lattice and the new non-magnetic YbFe2Ge2 heavy fermion compound using electrical resistivity measurements under high pressures (P ≤ 20 GPa). Pressure drives these systems to different types of magnetic quantum critical point, at different critical pressures (Pc): FM-QCP for CePt (Pc ∼12.1 GPa) and AF-QCP YbFe2Ge2 (Pc ∼9.4 GPa). Despite of that, the quantum critical behavior of both compounds at the two sides of the zero temperature transition is dominated by two dimensional (2D) spin fluctuations.

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Extended versus Local Fluctuations in Quantum CriticalCe(Ru1−xF

Cited by 38 publications

References 20 publications

The search for quantum critical scaling in a classical system

The search for quantum critical scaling in a classical system

Magnetic excitations in the spinel compoundLix[Mn1.96Li0.04]
Heitmann
¹
,
Schmets
²
,
Gaddy
³

et al. 2010
Phys. Rev. B
9
0
4
0
View full text Add to dashboard Cite

Quantum Criticality of CePt and YbFe₂Ge₂Heavy Fermions under Pressure

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Extended versus Local Fluctuations in Quantum CriticalCe(Ru1−xF

Cited by 38 publications

References 20 publications

The search for quantum critical scaling in a classical system

The search for quantum critical scaling in a classical system

Magnetic excitations in the spinel compoundLix[Mn1.96Li0.04]Heitmann1, Schmets2, Gaddy3 et al. 2010Phys. Rev. B9040View full textAdd to dashboardCite

Quantum Criticality of CePt and YbFe2Ge2Heavy Fermions under Pressure

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Magnetic excitations in the spinel compoundLix[Mn1.96Li0.04]
Heitmann
¹
,
Schmets
²
,
Gaddy
³

et al. 2010
Phys. Rev. B
9
0
4
0
View full text Add to dashboard Cite

Quantum Criticality of CePt and YbFe₂Ge₂Heavy Fermions under Pressure