Helical glasses near ferromagnetic quantum criticality

Thomson, S. J.; Krüger, Frank; Green, Andrew G.

doi:10.1103/physrevb.87.224203

Cited by 22 publications

(19 citation statements)

References 32 publications

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“…Recently it has been shown theoretically that another new phase possibly stabilizes near the FM-PM QPT [51][52][53][54][55][56] ; if there are quantum fluctuations in terms of fermionic particle-hole excitations on the Fermi surface, some deformations of the Fermi surface enhance the phase space available for the quantum fluctuations, and such a Fermi-surface instability causes another type of ordering to gain the free energy of the system [53][54][55][56] . It has been shown that two cases of new ordering are possible near the FM-PM QPT: (i) spiral magnetic phase, and (ii) spin-nematic phase 54 .…”

Section: Resultsmentioning

confidence: 99%

Unusual strong spin-fluctuation effects around the critical pressure of the itinerant Ising-type ferromagnet URhAl

et al. 2015

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Resistivity measurements were performed for the itinerant Ising-type ferromagnet URhAl at temperatures down to 40 mK under high pressure up to 7.5 GPa, using single crystals. We found that the critical pressure of the Curie temperature exists at around Pc ∼ 5.2 GPa. Near Pc, the A-coefficient of the AT 2 Fermi-liquid resistivity term below T * is largely enhanced with a maximum around 5.2-5.5 GPa. Above Pc, the exponent of the resistivity ρ(T ) deviates from 2. At Pc, it is close to n = 5/3, which is expected by the theory of threedimensional ferromagnetic spin fluctuations for a 2nd-order quantum-critical point (QCP). However, TC(P ) disappears as a 1st-order phase transition, and the critical behavior of resistivity in URhAl cannot be explained by the theory of a 2nd-order QCP. The 1st-order nature of the phase transition is weak, and the critical behavior is still dominated by the spin fluctuation at low temperature. With increasing pressure, the non-Fermi-liquid behavior is observed in higher fields. Magnetic field studies point out a ferromagnetic wing structure with a tricritical point (TCP) at ∼ 4.8-4.9 GPa in URhAl. One open possibility is that the switch from the ferromagnetic to the paramagnetic states does not occur simply but an intermediate state arises below the TCP as suggested theoretically recently. Quite generally, if a drastic Fermi-surface change occurs through Pc, the nature of the interaction itself may change and lead to the observed unconventional behavior.

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Section: Resultsmentioning

confidence: 99%

Unusual strong spin-fluctuation effects around the critical pressure of the itinerant Ising-type ferromagnet URhAl

et al. 2015

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“…LaCrGe 3 is therefore an example of a simple 3d-electrons ferromagnetic system for which a new magnetic phase appears as the Curie temperature is suppressed by pressure. Interestingly, this scenario has been considered recently by several theories [15,[23][24][25][26][27][28][29]. The idea is that particle-hole excitations corresponding to long wavelength correlations lead either to a change of order of the transition to the first order or to a new magnetic phase.…”

Section: Quantum Wingmentioning

confidence: 99%

Ferromagnetic quantum criticality: New aspects from the phase diagram of LaCrGe3

Taufour

Kaluarachchi

Bud’ko

et al. 2018

Physica B: Condensed Matter

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Recent theoretical and experimental studies have shown that ferromagnetic quantum criticality is always avoided in clean systems. Two possibilities have been identified. In the first scenario, the ferromagnetic transition becomes of the first order at a tricritical point before being suppressed. A wing structure phase diagram is observed indicating the possibility of a new type of quantum critical point under magnetic field. In a second scenario, a transition to a modulated magnetic phase occurs. Our recent studies on the compound LaCrGe 3 illustrate a third scenario where not only a new magnetic phase occurs, but also a change of order of the transition at a tricritical point leading to a wing-structure phase diagram. Careful experimental study of the phase diagram near the tricritical point also illustrates new rules near this type of point.

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“…Indeed, it was noted in Ref. [66] that the fluctuation-induced helimagnet might be rather susceptible to the effects of disorder, possibly explaining the apparent spin glass behaviour in the region of the phase diagram of CeFePO(Ref. [67]) where helimagnetism might otherwise be predicted.…”

Section: Partial Order In Mnsimentioning

confidence: 99%

Quantum Order-by-Disorder in Strongly Correlated Metals

Green

Conduit

Krüger

2018

Annu. Rev. Condens. Matter Phys.

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Entropic forces in classical many-body systems, e.g. colloidal suspensions, can lead to the formation of new phases. Quantum fluctuations can have similar effects: spin fluctuations drive the superfluidity of Helium-3 and a similar mechanism operating in metals can give rise to superconductivity. It is conventional to discuss the latter in terms of the forces induced by the quantum fluctuations. However, focusing directly upon the free energy provides a useful alternative perspective in the classical case and can also be applied to study quantum fluctuations. Villain first developed this approach for insulating magnets and coined the term order-by-disorder to describe the observed effect. We discuss the application of this idea to metallic systems, recent progress made in doing so, and the broader prospects for the future. CONTENTS

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Helical glasses near ferromagnetic quantum criticality

Cited by 22 publications

References 32 publications

Unusual strong spin-fluctuation effects around the critical pressure of the itinerant Ising-type ferromagnet URhAl

Unusual strong spin-fluctuation effects around the critical pressure of the itinerant Ising-type ferromagnet URhAl

Ferromagnetic quantum criticality: New aspects from the phase diagram of LaCrGe3

Quantum Order-by-Disorder in Strongly Correlated Metals

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