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Uhlarz, M.; Pfleiderer, C.; Hayden, Stephen M

doi:10.1103/physrevlett.93.256404

Cited by 237 publications

(227 citation statements)

References 27 publications

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“…The discontinuous suppression of ferromagnetism in pure ferromagnets 8,9,10,12 has led to the suggestion that for pure compounds ferromagnetism is always suppressed discontinuously under pressure. The conclusion drawn from the work on ZrZn 2 is related to the peculiar structure of the density of states near the Fermi level, notably there being a pronounced maximum in the vicinity of E F .…”

Section: Discussionmentioning

confidence: 99%

“…The conclusion drawn from the work on ZrZn 2 is related to the peculiar structure of the density of states near the Fermi level, notably there being a pronounced maximum in the vicinity of E F . 9,36 The suppression of the magnetic order in weak transition-metal magnets as function of temperature at ambient pressure is essentially driven by a broadening of the density of states (DOS) due to thermal fluctuations. Although hydrostatic pressure also acts to broaden the DOS via increased d-electron overlap, this transition in discontinuous, i.e., temperature and pressure suppress the magnetic order in a different fashion.…”

Section: Discussionmentioning

confidence: 99%

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Suppression of ferromagnetism inCeSi1.81under temperature and pressure

et al. 2006

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We have studied the pressure dependence of the magnetization of single crystalline CeSi1.81. At ambient pressure ferromagnetism develops below TC = 9.5 K. Below ∼ 5 K an additional shoulder in low-field hysteresis loops and a metamagnetic crossover around 4 T suggest the appearance of an additional magnetic modulation to the ferromagnetic state. The suppression of the magnetic order in CeSi1.81 as function of temperature at ambient pressure and as function of pressure at low temperature are in remarkable qualitative agreement. The continuous suppression of the ordered moment at pc ≈ 13.1 kbar suggests the existence of a ferromagnetic quantum critical point in this material.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Suppression of ferromagnetism inCeSi1.81under temperature and pressure

et al. 2006

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“…However, at least for FM 1 , it seems that P QCEP almost coincides with P c . 3 As a consequence, at 2.1 GPa, the crossover metamagnetic field is so low (0.05 T) that the observation of the Fermi surface in the PM regime is proscribed. 23 De Haas -van Alphen measurements pointed out the crossover between the FM 1 and FM 2 phases with an invariance of the Fermi surface topology.…”

Section: Discussionmentioning

confidence: 99%

“…In this critical region, only few experiments were carried out because of the severe experimental conditions of low temperature, high pressure, and high field. [1][2][3]5 Due to the recent focus on quantum criticality, the metamagnetism in itinerant ferromagnets has been recently revisited theoretically (see e.g. Ref.…”

Section: Introductionmentioning

confidence: 99%

Ferromagnetic Quantum Criticality Studied by Hall Effect Measurements in UCoAl

et al. 2013

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Hall effect measurements were performed under pressure and magnetic field up to 2.2 GPa and 16 T on a single crystal of UCoAl. At ambient pressure, the system undergoes a first order metamagnetic transition at the critical field Bm = 0.7 T from a paramagnetic ground state to a field-induced ferromagnetic state. The Hall signal is linear at low field and shows a step-like anomaly at the transition, with only little change of the Hall coefficient. The anomaly is sharpest at the temperature of the critical end point T0 = 12 K above which the first order metamagnetic transition becomes a crossover. Under pressure Bm increases and T0 decreases. The step-like anomaly in the Hall effect disappears at PM ≈ 1.3 GPa and the metamagnetic transition is not detected above the quantum critical end point (QCEP) at P∆ ≈ 1.7 GPa, Bm ≈ 7 T. Using magnetization data, we analyse our Hall resistivity data at ambient pressure in order to quantitatively account for both ordinary and anomalous contributions to the Hall effect. Under pressure, a drastic change in the field dependence of the Hall coefficient is found on crossing the QCEP. A possible Fermi surface change at Bm remains an open question.KEYWORDS: quantum critical end point, anomalous Hall effect, metamagnetism, ferromagnetism, UCoAl IntroductionThe metamagnetism in strongly correlated electron systems with Ising-type ferromagnetic (FM) behaviour is intensively studied because it produces a variety of unconventional effects. In some itinerant ferromagnets, such as UGe 2 1, 2 or ZrZn 2 , 3 one can drive the Curie temperature T C to 0 K by tuning an external control parameter like pressure, and the ground state is found to be paramagnetic (PM) above the quantum critical point (QCP). In theory, it has been suggested -and in some cases experimentally shown -that the second order ferromagnetic transition changes to first order at a tricritical point. 4 By applying a magnetic field above the critical point in the paramagnetic phase, such systems eventually recover their ferromagnetic state by undergoing a first-order metamagnetic transition at B m , drawing a wing-shape first order transition plane in the temperature (T ) -pressure (P ) -field (B) phase diagram. The first order transition terminates at high pressure and high field at T = 0 at the so-called quantum critical end point (QCEP). In this critical region, only few experiments were carried out because of the severe experimental conditions of low temperature, high pressure, and high field. [1][2][3]5 Due to the recent focus on quantum criticality, the metamagnetism in itinerant ferromagnets has been recently revisited theoretically (see e.g. Ref. 6,7). The main debate is whether a Lifshitz-like transition is associated with the occurence of metamagnetism.A good candidate to investigate itinerant metamagnetism is the heavy fermion compound UCoAl, with ZrNiAl-type hexagonal structure, space group P62m. At ambient pressure, its ground state is paramagnetic, with strong uniaxial magnetic anisotropy. By applying mag-

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“…Hence an l = 6 hexapole (hexatic) generalization of our model may be a more appropriate treatment of this system. By contrast, ZrZn 2 is a less likely candidate with its diamond like lattice structure and it is known to have magnetic order that is strongly three dimensional 53,54 and superconductivity 55 at temperatures below the Curie point. Nevertheless, we do not yet know of any thin-film experiments with Sc 3 In or ZrZn 2 , but hope that this work will encourage future work with these and related materials.…”

Section: → ←mentioning

confidence: 99%

Effective field theory of an anomalous Hall metal from interband quantum fluctuations

Chua

Assawasunthonnet

Fradkin³

2017

Phys. Rev. B

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We construct an effective field theory a two-dimensional two-component metallic system described by a model with two Fermi surfaces ("pockets"). This model describes a translationally invariant metallic system with two types of fermions, each with its own Fermi surface, with forward scattering interactions. This model, in addition to the O(2) rotational invariance, has a U (1) × U (1) symmetry of separate charge conservation for each Fermi surface. For sufficiently attractive interactions in the d-wave (quadrupolar) channel this model has an interesting phase diagram that includes a spontaneously generated anomalous Hall metal phase. We derive the Landau-Ginzburg effective action of quadrupolar order parameter fields which enjoys an O(2)×U (1) global symmetry associated to spatial isotropy and the internal U (1) relative phase symmetries respectively. We show that the order parameter theory is dynamically local with a dynamical scaling of z = 2 and perform a one-loop renormalization group analysis of the Landau-Ginzburg theory. The electronic liquid crystal phases that result from spontaneous symmetry breaking are studied and we show the presence of Landau damped Nambu-Goldstone modes at low momenta that is a signature of non-Fermi liquid behavior. Electromagnetic linear response is also analyzed in both the normal and symmetry broken phases from the point of view of the order parameter theory. The nature of the coupling of electromagnetism to the order parameter fields in the normal phase is non-minimal and decidedly contains a precursor to the anomalous Hall response in the form of a order-parameter-dependent Chern-Simons term in the effective action.

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Quantum Phase Transitions in the Itinerant FerromagnetZrZn2

Cited by 237 publications

References 27 publications

Suppression of ferromagnetism inCeSi1.81under temperature and pressure

Suppression of ferromagnetism inCeSi1.81under temperature and pressure

Ferromagnetic Quantum Criticality Studied by Hall Effect Measurements in UCoAl

Effective field theory of an anomalous Hall metal from interband quantum fluctuations

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